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UNION OF SOUTH AFRICA.

DEPARTMENT OF AGRICULTURE.

EIGHTEENTH REPORT

OF THE

DIRECTOR OF VETERINARY SERVICES AND ANIMAL INDUSTRY,

ONDERSTEPOORT,

PRETORIA.

AUGUST, 1932.

PART II.

1522—8/3/32—1,500.

The Government Printer, Pretoria, 1932

Department of Agriculture,

Director of Veterinary Services and Animal Industry, Onderstepoort Laboratories,

Pretoria, South Africa,

Avgust, 1932.

List of Reports issued by the Director of the Onderstepoort Laboratories.

Report of the Government Veterinary Bacteriologist of the Transvaal for the year 1903-4.*

Report of the Government Veterinary Bacteriologist of the Transvaal for the year 1904-5.*

Report of the Government Veterinary Bacteriologist of the Transvaal for the year 1905-6.*

Report of the Government Veterinary Bacteriologist of the Transvaal for the year 1906-7.*

Report of the Government Veterinary Bacteriologist of the Transvaal for the year 1907-8.*

Report of the Government Veterinary Bacteriologist of the Transvaal for the year 1908-9.*

Report of the Government Veterinary Bacteriologist of the Transvaal for the year 1909-10.* First Report of the Director of Veterinary Research, August, 1911.*

Second Report of the Director of Veterinary Research, October, 1912.*

Third and Fourth Reports of the Director of Veterinary Research, November, 1915.* Fifth and Sixth Reports of the Director of Veterinary Research, April. 1918.*

Seventh and Eighth Reports of the Director of Veterinary Research, April, 1918.*

Ninth and Tenth Reports of the Director of Veterinary Education and Research, April, 1923.

Eleventh and Twelfth Reports of the Director of Veterinary Education and Research, Part

I, September, 1326.

Eleventh and Twelfth Reports of the Director of Veterinary Education and Research, Part

II, January, 1927.

Thirteenth and Fourteenth Reports of the Director of Veterinary Education and Research, Parts I and II, October, 1928.

Fifteenth Report of the Director of Veterinary Services, Parts I and II, October, 1929. Sixteenth Report of the Director of Veterinary Services and Animal Industry, August, 1933.

Seventeenth Report of the Director of Veterinary Services and Animal Industry, Parts I and II, August, 1931.

Eighteenth Report of the Director of Veterinary Services and Animal Industry, Parts I and II, August, 1932.

P. J. du TOIT,

Director of Veterinary Services and Animal Industry.

* Now out of print, iii

CONTENTS

PART I.

SECTION I.

Protozoal Diseases.

PAGE

W. O. Neitz and Bovine Anaplasmosis. A Method of obtaining Pure Strains P. J. du Toit of Anaplasma marginale and Anaplasma centrale through

Antelopes 3

A. B. M Whitnall The Trypanosome Infections of Glossina pallidipes in the

Umfolosi Game Reserve, Zululand 21

E. M. Robinson and A Note on Aegyptianella pullorum in the Fowl in South Africa 31 J. D. W. A. Coles

SECTION II.

Virus Diseases.

P. J. du Toit and The Immunization of Mules, with Formalized Horse-Sickness

W. O. Neitz virus 35

C. Jackson and On the Aetiology of Heartwater 49

W. O. Neitz

V • 0. Neitz and Rabies as it occurs in the Union of South Africa 71

I. P. Marais

D. G. Steyn East African Virus Disease in Pigs 99

A. S. Canham . . . . Immunization of Fowls against Fowl Pox by Use of Pigeon

Pox Virus Ill

SECTION III.

Bacterial Diseases.

J. R. Scheuber.. The Occurrence of B. oedematiens in South Africa 141

SECTION IV.

Parasitology.

P. J. du Toit and Goat Mange. The Infectivity of Kraals 145

G. A. H. Bedford

H. 0. Monnig.... Wild Antelopes as Carriers of Nematode Parasites of Domestic

Ruminants. Part II 153

H. 0. Monnig.... Syngamus indicus : A New Nematode from the Indian Elephant 173

R. J. Ortlepp. . . . On a New Species of Tetramcres (Tetrameres paradisea sp. nov.)

from Stanley Cranes 17 7

R. .J. Ortlepp.... Some Helminths from South African Chiroptora 183

H. H. Curson.... Distribution of Glossina in the Bechuanaland Protectorate... 197

G. A. H. Bedford Description of Argos striatus, a new Species of Tick 221

G. A. H. Bedford A Synoptic Check-List and Host-List of the Ectoparasites

found on South African Mammalia, Avos, and Reptilia. (Second Edition) 223

v

PART II.

SECTION V.

Mineral Deficiency and Metabolism.

PAGE

P. J. nr Toit. A. I. A Study of the Mineral Content and Feeding Value of Natural

Malan, J. G. Pastures in the Union of South Africa. (First Report).. 525

Louw, C. R.

Holzapfel and G. C. S. Rof.ts.

M. H kn'Rici Cystine and Sulphur Content of Bushes and Grasses in a

Karroid Area (Fauresmith) 579

I). G. Steyn The Effects of Sulphur on Merino Sheep and their Resistance

to Potassium Cyanide Poisoning 597

P. J. nr Toit, A. I. Studies in Mineral Metabolism XVIII. Phosphorus in the

Malan, and J. Nutrition of Sheep. (Final Report) 611

W. Groenewald

J. E. Duerden, V. Studies in Mineral Metabolism XIX. Influence of Phosphorus

Bosman and P. S. and Other Minerals on Wool Growth 631

Botha

A. I. Malan, P. J. Studies in Mineral Metabolism XX. Iodine in the Nutrition

nr Toit, and J. of Sheep 651

W. Groenf.walo

A. I. Malan and Studies in Mineral Metabolism XXI. A comparison of Phos- P. .1. nr Toit phatic Supplements for the Prevention of Aphosphorosis

J. S. Otto Studies in Mineral Metabolism XXII. Phosphorus, Calcium

and Protein

• 1. G. Bkkker.... Studies in Mineral Metabolism XXIII. Phosphorus and Iodine

Supplements in Field Experiments with Sheep

.1. G. Bekker. . . . Studies in Mineral Metabolism XXIV. On the Administration

of Phosphorus to Animals through their Water Supply. . J. W. Grof.newald Studies in Mineral Metabolism XXV. The Effect of Calcium and Magnesium Supplements on the Growth of Merino

Sheep

P. .). di Toit, A. I. Studies in Mineral Metabolism XXVI. The Effect of Fluorine

Malan, J. W. on Pregnant Heifers

Groenewald, and G. de Kock

SECTION VI.

677

703

733

751

799

805

Sex Physiology.

•I. Qxjinlan and Gland Grafting in Merino Sheep. Preliminary Observations

I. P. Marais on its Influence (c) on Castrated Sheep 819

J. Quinlan, G. S. The Vitality of the Spermatozoon in the Genital Tract of the Mare, and E. L. Merino Ewe, with Special Reference to its Practical Roux Application in Breeding 831

SECTION VII.

Poisonous Plants.

D.	G. Steyn	Investigations into the Toxicity of Known and Unknown Poisonous Plants in the Union of South Africa	871
D.	G. Stey'n	Chrysocoma t e tut i folia Berg. Poisoning in Angora Goats and the Development of Tolerance	893
IX	G. Stf.y'n	A Study of the Factors concerned in the Determination of the Toxicity of Cotyledon orbiculata	899
I).	G. Steyn	Experiments with Potassium Cyanide on Rabbits	939
I). (	G. Steyn and 3. de Kock	Crotalanosis in Sheep	947
Claude Rimincton	Isolation and Chemical Examination of the Poisonous Principles of IJimorphotheca spectabilis Schltr. and Dimorphotheca Zeyheri Sond	955

SECTION VIII.

Animal Industry.

PAGE

J. E. Deurden, C. Growth of Wool in the Merino 973

A. Murray, and P. S. Botha

J. E. Deurden and Staple Length, Variation and Distribution in the Eleece of the

E. W. Palmer Merino 991

SECTION IX.

Dips and Dipping.

H. Graf and T. J. Researches into Dips and Dipping. A. Lime-Sulphur Dips.

Wilken-Jorden Paper 1. General Introduction. Lime Sulphur Dips. . . . 1005

T. J. Wilken- Researches into Dips and Dipping. A. Lime-Sulphur Dips.

Jorden Paper II. A New Laboratory Method of Chemical Analysis 1015

T. J. Wilken- Researches into Dips and Dipping. A. Lime-Sulphur Dips.

Jorden Paper III. A Preliminary Study of a Colorimetric Method

as a Rapid Means of Control of Polysulphide Solutions.. 1029

SECTION X.

Miscellaneous.

.T. Quinlan and The Normal Temperature of Merino Sheep during January in

G. S. Mare the Karroo, and How it is Intluenced by Exercise 1037

H. H. Curson. . . . Notes on the Flora of Ngamiland and Chobe. Part T. Outline

of the Floral Regions 1041

N. T. v. d. Linde A Peculiar Case of Traumatism Affecting the Metatarsal Bones 1061

G. C. van Drimme- Anatomical Studies, No. 28. Hypospadias in a Merino Ram 1063 len and A. R.

Thiel

H. H. Curson.... Anatomical Studies, No. 29. A Further Note on Free-Martinism 1067

H. H. Curson.... Anatomical Studies, No. 30. On Two Cases of Atresia Ani.. 1073

H. H. Curson.... Anatomical Studies, No. 31. On Two Cases of Acardiacus.. 1077

W. D. Malherbe. Anatomical Studies, No. 32. Atresia Ani with Rectum opening

into Vagina in a Kitten 1081

W. J. Wheeler.. Anatomical Studies, No. 33. Micrognathy in a Lamb 1083

G. S. Mare Anatomical Studies, No. 34. Faulty Jaws in Sheep 1085

I. P. Marais Anatomical Studies, No. 35. On the Origin of an Abdominal

Cyst found in a Domestic Hen 1087

H. H. Curson.. . . Anatomical Studies, No. 36. On Two Anomalies of the Cervix

Uteri in a Merino Sheep 1091

R. Bigalke Anatomical Studies, No. 37. On a Hybrid Duiker 1093

Section V

Mineral Deficiency and Metabolism.

P. J. DU Toit, A. I. Malan, J. G. Louw, C. It. Holz-

APFEL AND G.

C. S. Roets.

M. Henrici

D. G. Steyn

P. J. du Toit, A. I. Malan and J. W. Groenewald.

J. E. Duerden, Y. Bosman and P. S. Botha.

A. I. Malan, P. J. du Toit AND J. W. Groenewald.

A. I. Malan and P. J. du Toit

J. S. Otto

J. G. Bekker ...

J. W. Groene- wald.

P. J. du Toit, A. I. Malan, J. W. Groene- wald and G. de Kock.

A Study of the Mineral Content and Feeding Value of Natural Pastures in the Union of South Africa. (First Report.)

Cystine and Sulphur Content of Bushes and grasses in a Karroid Area (Fauresmith).

The Effects of Sulphur on Merino Sheep and their Resistance to Potassium Cyanide Poisoning.

Studies in Mineral Metaholism XVIII. Phos- phorus in the Nutrition of Sheep. (Final Report.)

Studies in Mineral Metabolism XIX. Influence of Phosphorus and Other Minerals on Wool Growth.

Studies in Mineral Metabolism XX. Iodine in the Nutrition of Sheep.

Studies in Mineral Metabolism XXI. A com- parison of Pliosphatic Supplements for the Prevention of Aphosphorosis.

Studies in Mineral Metabolism XXII. Phos- phorus, Calcium and Protein.

Studies in Mineral Metabolism XXIII. Phos- phorus and Iodine Supplements in Field Experiments with Sheep.

Studies in Mineral Metabolism XXIV. On the Administration of Phosphorus to Animals through their Water Supply.

Studies in Mineral Metabolism XXV. The Effect of Calcium and Magnesium Supple- ments on the Growth of Merino Sheep.

Studies in Mineral Metabolism XXVI. The Effect of Fluorine on Pregnant Heifers.

IStk Report of the Director of Veterinary Services and Animal Industry, Union of South Africa , August . 1932.

A Study of the Mineral Content and Feeding Value of Natural Pastures in the Union of South Africa — (First Report).

By P. J. DU TO.IT, B.A., Dr. Phil., Dr. Med. Yet., D.Sc.(Agric.), Director of Veterinary Services and Animal Industry,

A. I. MALAN, D.Sc., Biochemist, Onderstepoort,

J. G. LOUW, M.Sc., Chemist, Onderstepoort,

C. R. HOLZAPFEL, M.Sc., Chemist, Onderstepoort, and

G. C. S. POETS, B.So., Botanist, Onderstepoort.

CONTENTS.

I. Introduction.

II. Outline of Investigation.

1. Origin of the scheme.

2. Object of the Investigation.

3. Methods employed :

(i) Soil analyses,

(ii) Analyses of pasture,

(iii) Blood analyses.

4. Scope of the analytical work and methods employed.

5. Technique.

6. Experimental plan :

(a) Mineral Survey of the Union :

(i) Collection of soil samples.

(ii) Collection of samples of pasture.

(iii) Collection of blood samples.

(h) Experimental plots.

(c) Extension of blood analyses.

525

19

MINERAL CONTENT ANI) FEEDING VALUE OF S.A. PASTURES.

III. Provisional Results.

1. The chemical composition of soils and pasture from

different areas in the Union.

2. Discussion of results :

(a) Explanation of terms.

( b ) Classification of pasture.

( c ) Crude protein, fibre and carbohydrate plus ether soluble extract.

(d) Phosphorus content.

( e> ) Phosphorus content of pastures in relation to the phosphorus content of soils.

(/) CaO, MgO, K,0, Na20, and Cl.

3. The chemical composition of the same species of grasses

from different areas and discussion.

4. The chemical composition of different species from the

same area and discussion.

5. Inorganic phosphorus in the blood and discussion.

IV. Concluding Remarks.

1. Correlation of results obtained for phosphorus from soil,

pasture and blood analyses respectively.

2. Comparison of the three methods of studying phosphorus

deficiency.

Y. Summary.

I. INTRODUCTION.

Pasture studies may be regarded as one of the most important branches of modern agricultural research. It is of recent origin and has already yielded far-reaching results. Outstanding is the work of Woodman and his collaborators at Cambridge on the effect of growth on the feeding value of pasture. The economic value of this work, which is closely associated with what is known as the new method of grassland management, can hardly be overestimated. Pasture, herbage, if correctly managed and timely used may be regarded as a protein concentrate, whereas the same pasture when allowed to mature may have low feeding value and show a wide nutritive ratio. It is admitted, of course, that the application of the findings of Woodman and his co-workers hold good primarily for the climatic conditions under which they worked, which are, generally speaking, a high rainfall, well distributed over the year, and a temperate climate. But it is fully realized that pasture research under other conditions may have equally important bearings on and suggest vast changes in the existing methods of pasture management. It is not too early to say that the preliminary work done by Staples and Taylor (1926-1931) at the Cedara School of Agriculture, Natal, is already indicative of many errors in the system of pasture management at present in vogue in South Africa.

526

DU TOIT, MALAN, HOEZAPiFEL, LOUW, AND ROETS.

M ention should also be made here of the work of Orr and his staff at the Rowett Research Institute, on the feeding value of pas- ture from the aspect of its mineral content, and of the investigations of Stapledon and his colleagues (1924-1931) at the Welsh Plant Breeding Station into chemical composition and seasonal variations.

In the Union of South Africa the need for improvement of pastures is much more urgent than in England and other European countries. Approximately 95 per cent, of our country consists of natural pasture and most of this is of very low carrying capacity. This need was realized by some of the early investigators and Huteheon on the animal husbandry side and Juritz on the chemical side, carried out some very valuable work twenty to thirty years ago.

Amongst the later investigators who stressed the need for supple- menting the deficiencies of our pastures, pride of place must be given to Theiler. He and his co-workers began their investigations with the study of lamsiekte, a disease which was found to have its ultimate cause in the phosphorus deficiency of the soil and pasture. They pursued their researches into this deficiency further and found that it played a pre-eminent role in the nutrition of animals. By supply- ing the deficient minerals they were able to breed prime animals on veld which ordinarily only produced scrubs. In these investigations the study of the pasture itself occupied a prominent place and a large volume of data has been collected at Onderstepoort mainly on the chemical composition of grasses.

As this work progressed it was found that phosphorus deficiency was far commoner in the Union than was thought to be the case at first. But the mere knowledge that the grasses from a certain area were deficient in phosphorus was not sufficient. In order to obtain useful information on their feeding value a systematic study became necessary of such factors as soil composition, climatic conditions, seasonal variation, stage of development of the plant, differences due to species, etc.

It is our intention to embody the study of most of these aspects of the problem in the present investigation. Nevertheless the work must remain incomplete because of the immense area to be covered and the limitation of staff and funds. That we were able to under- take the present investigations at all on the lines contemplated, is due in large measure to the generosity of the Empire Marketing Board, who supplied part of the funds and to whom grateful acknow- ledgment is made herewith.

II. OUTLINE OF THE INVESTIGATION.

1. Origin of the Scheme.

The findings of recent investigators that a phosphorus deficiency is widespread in many parts of Africa, Australia and other countries, emphasized the scope of this problem and the necessity of studying it further. The possibility of other mineral deficiencies playing an important role was also kept in mind when the scheme was under consideration.

At the same time it was realized that excellent opportunities would become available during the course of the investigation for studying the feeding value of pastures as, far as the figures for crude protein, fibre, carbohydrates plus fat content could provide a

527

MINERAL CONTENT AND FEEDING VALUE OF S.A. PASTURES.

criterion. In other words, the need of more detailed data on pastures generally and their bearing on problems of nutrition and disease was felt when this investigation was conceived.

2. Object of the Investigation.

The investigation was suggested by the need of more accurate knowledge in South Africa regarding the distribution of phosphorus- deficient and phosphorus-sufficient areas. The first object of the survey was, therefore, to collect data which would enable us to map out the Union of South Africa into areas according to the phosphorus content of the soil and pasture.

But the investigation was not intended to have a local applica- tion only. As indicated above, the problem applies to other parts of the Empire (East and West Africa, Australia, etc.) and other coun- tries as well, and it was our desire to test out various methods of research in South Africa which would afterwards be of benefit to those other countries. These methods are discussed here briefly.

3. Methods Employed.

In previous work in South Africa phosphorus deficiency in an area was always determined by the analysis either of the soil itself or of pasture grasses grown in that area. In 1927, Malan, Green and Du Toit showed that phosphorus deficiency is also reflected in the blood of animals grazing on such pasture. In t lie present inves- tigation it was decided, therefore, to analyse —

(a) the soil from the selected areas,

( b ) grasses growing on that soil,

( c ) blood of cattle grazing on such pasture.

It was hoped to establish a definite correlation between these three sets of data and possibly to determine whether any one of these procedures yielded sufficiently accurate results to render the other two superfluous. The advantages and disadvantages of these methods will be discussed below.

4. Scope of the Analytical Work and Methods of Analysis.

Not only phosphorus but also Ca, Mg, Na, K and Cl were in- cluded; while analyses for crude protein, fibre and carbohydrate plus fat have also been carried out.

The methods employed for grass and blood analyses for inorganic constituents are those described by Malan and Van der Lingen (1931). The method for sodium has been modified slightly in that it was found unnecessary to remove phosphorus by the addition of alcoholic zinc acetate. After the precipitation of sodium the precipitate is washed with a saturated solution of uranyl zinc sodium acetate in 96 per cent, alcohol and stirred with a small glass rod. This proce- dure is necessary to break up the uranyl phosphate which forms as the top layer of the precipitate in the centrifuge tube.

Protein and fibre were determined according to the methods described by Wood (1911). Ether soluble extracts were not deter- mined as their values show little variation, and are insignificantly small compared with those for carbohydrates, while the method takes

528

DU TOIT, MALAN, HOLZAPFEL, LOUW, AND POETS.

up a great deal of time when large numbers of determinations have to he made. The results, therefore, yield crude protein, fibre, carbo- hydrates plus ether soluble extract, silica, and the individual inor- ganic constituents mentioned above. Only the available inorganic constituents were determined in the soil by shaking 50 grams of soil with 250 c.c. X/ 20 hydrochloric acid solution for 60 minutes, filter- ing and washing to 1,000 c.c. This extract was used for analysis and the micro-methods, described by Steenkamp (1931), employed. The extract for chlorine was made by substituting N / 500 H2S04 for HC1 and following the same procedure.

5. Technique.

The technique offers no difficulty after the usual experience with micro-chemical work has been gained. The results of inorganic phos- phorus in the blood are affected by the interval between the time of bleeding in the field and the actual analyses in the laboratory, a matter of about 3 days usually. Hydrolysis of organic phosphorus results in an increase of inorganic phosphorus as explained by Malan (1930). Hence the procedure followed is such that would expedite the despatch of the blood from the field to Onderstepoort. Briefly, the blood is drawn, precipitated and immediately despatched to Onder- stepoort, where it is analysed for inorganic phosphorus on arrival. Under those conditions the hydrolysis, although by no means negligible, does not increase low values sufficiently to be classed with figures indicating phosphorus sufficiency, although, obviously, borderline cases are likely to be missed. In any case, the object of the investigation is not to obtain correct values for inorganic phos- phorus in the blood of animals but to diagnose phosphorus deficiency or sufficiency, and for that purpose the increased values provide enough data.

There is an upward grading of all values after hydrolysis, which means that low values for inorganic phosphorus are higher and that normal values will lie above that level, but the figures still lend themselves to interpretation, provided the age and ( lass of bovine (lactating or dry cow, ox, etc.) and the time between bleeding and analysis be given. At present data are being collected on the monthly inorganic phosphorus content of the blood of bovines of different ages under phosphorus deficient and phosphorus sufficient conditions in the Vryburg area. The inorganic phosphorus is determined at bleeding time, while separate portions of the blood of each animal are treated in the regular way for all the samples of the surveys, forwarded to Onderstepoort and analysed here after different periods of hydrolysis. Correction values may then lie calculated for both low and high figures under the conditions that the surveys are actually carried out. This point will again be referred to later in the publication.

6. Experimentai, Plan.

(a) Mineral Surrey of the Union.

One part of the scheme deals with a survey of the Union. Samples of soil, vegetation and blood are sen! in by about forty Government field Veterinary Officers at the four seasons of the year. Each officer selects at least one area for collection in his district and makes successive collections from if provisionally for two years, in

529

MINERAL CONTENT AND FEEDING VALUE OF S.A. PASTURES.

order to study the effect of climate on the composition of the soil, vegetation and the effect of the latter on the blood constituents. On the accompanying map the areas from which samples have been collected so far are marked.

Experimental Plan: Mineral Survey of the Union.

• Shows areas from which samples have been collected.

The first survey took place in May, 1930, the second in May, 1931, after which arrangements were made for the regular carrying out of surveys annually in October, January, April and July.

Soil samples are taken in the ordinary way from a paddock, while collections of each of the prominent grasses in the paddock are made. Blood is drawn from ten bovines — preferably dry cows, which receive no supplementary feeding. Briefly the procedure is as follows: About a month before a survey is to take place a circular letter is forwarded to all Government field Veterinary Officers stating exactly what is to be done and notifying the officers that small bottles containing trichloracetic acid for the collection and precipitation of blood will be despatched in due course. A copy of such a circular is printed below: —

P.O. Onderstepoort,

Pretoria (Date.)

To all Senior and Government Veterinary Officers.

Mineral Survey No. 6.

Time : The next survey will take place from 1st July to 31st July, 1932, and 1 trust that all officers without exception will provide the material during that time.

Farm :

Collections of soil, pasture, and blood samples are to be made.

(i) Soil Samples. — In collecting soil samples officers must use their own discretion. For instance, in a region where grass is abundant the bulk of the grass roots will probably not penetrate to a greater depth than about 12 inches,

530

DU TOIT, MALAN, HOLZAPEEL, LOUW, AND POETS.

and a sample of soil taken to that depth will probably he a good representative sample; on the other hand, for shrubs, it may be necessary to take samples down to about 2 feet or more. Preliminary work such as digging up shrubs or grass in order to find out the depth of the roots is essential, and the actual samples can be taken according to the findings of the preliminary work.

After selection of the farm or portion of it, where soil samples have to be taken, a patch of about 12 by 12 inches is cleared of all vegetation. A hole of the required depth is dug next to the clear patch, and a slice about 2 inches wide cut down the perpendicular side, where the vegetation has been removed. This is transferred to the bag provided. The operation is repeated in at least four places, so as to obtain a representative soil sample of the farm or portion of it decided upon ; all four samples are transferred to the same bag. If the soil is very moist it should be air-dried before despatch to Onderstepoort.

(ii) Grass Samples. — Should an officer decide, after consultation with the farmer, that there are half a dozen varieties of edible grasses in the area under survey, he should collect at least one pound of each variety separately, thereby assisting the process of classification which has to be carried out at Onderstepoort. The grass must be cut as near the ground as possible and made air-dry. Each variety is wrapped in paper and all are then placed in a bag or sugar-pocket and forwarded to Onderstepoort by rail.

(iii) Blood Samples. — Each officer will be provided with two sets of bottles before the beginning of July. The ten small bottles contain sodium citrate as anticoagulant and are to be used for the collection of blood. The larger bottles contain 100 c.c. of 2'5 per cent, trichloracetic acid solution for the precipitation of the blood proteins. After bleeding into the small bottles, 25 c.c. blood are transferred in a pipette to the trichloracetic acid solution. The bottle is then corked and shaken vigorously for about half a minute, when it is ready for dispatch to Onderstepoort. it is not necessary to clean the pipette after the transfer of every sample of blood to the trichloracetic acid solution, unless rinsing is obviously necessary, when only distilled water should be used. Bovine blood is preferred, and only from animals which do not receive supplementary feeding in any form, least of all any phosphatic product, but which are entirely dependent upon the pasture for their existence. Owners may feel reluctant to have their poorest animals bled, and even you may be inclined to select the best conditioned animals. This clearly partly defeats our purpose, as a figure obtained for inorganic phosphorus in the blood of the best conditioned animals will not be a good criterion of the phosphorus sufficiency or deficiency of the veld unless some of the poorest animals or, alternately, o poor ones and 5 that are in good condition he selected. Full-grown dry cows are the best types to select, for, whereas in lactating cows milk production causes an extra drain of phosphorus, oxen usually produce work, and the phosphorus reserve of young stock is undoubtedly high, causing the blood phosphorus to remain high for a considerable time in spite of deficiency. Full-grown animals must, therefore, be selected wherever possible and in the following order of merit: —

1. Full-grown dry cows, pregnant or not.

2. Full-grown oxen with a note about the work done.

3. Full-grown lactating cows with a note about milk yield.

4. Younger animals older than 18 months.

N.B. — Please give all the available details about individual animals bled, e.g. age, sex, etc., on the form provided. The blood is to be forwarded to Onderstepoort by post immediately after precipitation.

General. — (a) Kindly fill in the form placed in the wooden box containing the bottles and dispatch it with the precipitated blood samples.

(b) All empty bleeding bottles should be returned by placing them in the bags containing the grass samples.

(c) All the samples, i.e. soil, grass, and blood, are to be taken on the same day or on successive days.

(d) Animals must not be driven any distance before bleeding, as the inorganic phosphorus of the blood rises as a result of exercise.

(Sgd.) Director of Veterinary Services.

531

MINERAL CONTENT AND FEEDING VALUE OF S.A. PASTURES.

The form referred to in (a) of the last paragraph is printed below : —

Name of Veterinary Officer

Farm and district from which samples were collected

Name and address of owner

Date when bled

Date of dispatch of samples

Blood samples: 1

2

3

4

6,

S

9

10

Under blood samples insert whether from heifer, dry cows, lactating cow, ox, etc., stating approximate age and giving details about condition, health, and breed.

Rainfall: January

February

March

April

May

June

July

August

September

October

November

December

The samples of vegetation are identified on arrival and selected specimens placed in the herbarium for future reference, if necessary. Each variety is labelled green, mature or mixed, according to its appearance, then finely ground in a mill, after which it is ready for analysis. About 200 grass samples are received for each survey, which means that about 1,600 analyses have to be made before the following survey begins.

It is evident that the above scheme, although elaborate, is in- complete. An estimate — admittedly very important — may be formed of the feeding value of grasses at the different seasons, but such factors as the variation of the mineral content of separate species with age, will remain unknown, and hence direct comparisons of the results of the analyses of different species of grasses from the same area or of the same species from different areas must remain unwise when different soil and climatic conditions of which very little is known, exist. Besides, the period of growth when one is dealing with both early and late growing varieties must be known in order to make such comparisons. In order to study these factors further ihe survey was extended to include experimental plots.

532

DU TOIT, MALAN, HOLZAPFEL, LOTJW, AND ROETS.

( b ) Experimental Plots.

This phase of the work began in 19-31, when important indi- genous grasses were planted in separate plots of virgin soil, tended until good growth was assured, after which only weeding took place. At present about 20 such plots are in full growth and constant addi- tions are being made. Older plots are in existence in Pretoria about 7 miles from Onderstepoort on a different kind of soil for a study of the influence of soil type on the composition of grasses both by the Division of Chemistry and by the writers.

The objects of the plot experiments may be briefly summarized as follows :

(1) The effect of growth on the chemical composition of pas-

ture. For this purpose monthly, two-monthly, three- monthly, four-monthly, etc., cuttings are analysed from each plot, i.e. of each variety of grass.

(2) The variation in chemical composition of different species of grasses of the same period of growth.

(3) The effect of seasonal variation in growth on the chemical composition and on the yield of grass.

(4) The chemical composition of successive cuttings of the same variety of grass. This means that, if a portion of a plot is cut for a sample of monthly growth, the same portion will be cut again after another month, i.e. when a two- monthly sample is taken from another portion of the plot; this procedure is repeated for both one-monthly and two- monthly cuttings, etc,., at later samplings.

(5) The chemical composition of different parts of the same plant at different stages of growth. For this purpose, leaves, stalks and haulms will be analysed separately at the different periods.

Climatic conditions will obviously play a most important part in the work on plot experiments, but these will be recorded and con- sidered along with the data.

( c ) Extension of Blood Analyses.

A recent development of the experimental plan is towards a greater utilization of the results of blood analysis for the delimitation of phosphorus-deficient and phosphorus-sufficient areas of the Union. The advantage obviously lies in the fact that blood can be drawn with great ease by the Government Veterinary Officers from animals in a number of areas in their districts, forwarded to Onderstepoort at very little cost and analysed for inorganic phosphorus with a minimum of labour. This application of blood analysis is based upon the findings of Malan, Green and Du Toit (1927), viz., that animals suffering from aphosphorosis show a low figure for inorganic phosphorus in their blood.

III. A FEW PROVISIONAL RESULTS.

1. The Chemical Composition of Soils* and Pasture! from Different Areas in the Union.

* The soil analyses were kindly undertaken by the Division of Chemistry, Pretoria.

t Mr. G. W. B. van der Lingen, M.Sc., Chemist, was responsible for the analytical work of the Mineral Survey in May, 1930.

633

Values in Gm. per 100 Gm. Dry Material.

N for pasture is given as crude protein. The numerals in column one refer to the surveys in May, 1930, May, 1931, and October, 1931. respectively.

MINERAL CONTENT AND FEEDING VALUE OF S.A. PASTURES

Farm. * Nature of Pasture.	Mixed. Mixed. Mixed.	Mixed, mainly mature. Mixed, practically all mature.	Mixed, mainly mature. Old dry mature.	Mixed, mainly mature. Mixed, practically all mature. Old dry mature.
Roodepoort No. 152 Aberdeen No. 291.. Roodepoort No. 8. . Roodepoort No. 152 Aberdeen No. 291.. Roodepoort No. 8. .	Hartebeestfontein No. 51 Hartebeestfontein No. 51 Hartebeestfontein No. 51	Brooklyn Brooklyn Brooklyn	Frischgewaagd No. 82 De Grootboom No. 214 Frischgewaagd No. 82 De Grootboom No. 214
Carh. + Ether Sol. Ext.	56-3	54-9	53-5	58-2
*
	III 1 u	1 II 11°	III 11=	1 1 1 1 u
E		o -f
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534

TABLE 1 — (continued).

c 9

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MINERAL CONTENT AND FEEDING VALUE OF S.A. PASTURES.

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537

TABLE 1 — (continued)

MINERAL CONTENT AND FEEDING VALUE OF S.A

PASTURES

538

DU TOIT, MALAN, HOLZAPFEL, LOUW, AND ROETS.

Mixed, mainly mature. Mixed, practically all green. Mixed.

ill i 1

J

Mixed.

Mixed, mainly mature. Mixed, practically all green.

Leaves of shrubs.

Green grass and shrubs.

Mixed, practically all mature. Mixed grass and shrubs. Mixed.

Endwell

Mt. Hupelev

Endwell

Mt. Hupeley

Cradock Place

Woodlands

Lombardspoat

Penroek

Kingston

Penroek

Kingston

Primestone

Ml IM

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115

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26. Port Elizabeth J Cape Province

27. Bathurst, Cape., Province

28. Albany, Cape ^ Province

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5-‘?o

MINERAL CONTENT AND FEEDING VALUE OF S.A. PASTURES.

Mixed, mainly green grass and shrubs.

Mixed, mainly green.

Mixed, mainly mature. Old dry mature.

Mixed, mainly mature. Mixed grass and shrubs.

Mixed, mainly mature. Mixed, practically all mature.

Mixed, practically all mature. Mixed.

Allandale

Greefputs

Grecfputs

Bisshops Glen

Glen Shields

Naseby Thorns

Nasebv Thorns

Content

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540

DU TOIT, MALAN, HOLZAPFEL, LOTJW, AND POETS.

ipe Province

TABLE 1- — (continued).

MINERAL CONTENT AND FEEDING VALUE OF S.A. PASTURES.

Nature of Pasture.

Green grass and shrubs.

Mixed, practically all mature.

Mixed.

Mixed, practically all mature.

Mixed.

Mixed, mainly green.

Mixed.

Mixed, practically all mature.

Thick reedy grass, mixed, mainly mature.

Mixed.

Old mature cyperaceae.

Mixed, practically all mature.

Farm.

St. Hilda

Oakiands

Holmesdale

Kimbolton

Halifax

Homefarm

Vanclusz

Mountain View

Commissiedrift

Commonage

Perse verence

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Chatsworth

Welbeloond

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59. Somerset West,

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60. Malmesbury, 9

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61. Tygerberg, Cape Province

62. Kimberley, Cape , Province

512

I)U TOIT, MALAN, HOLZAPFEL, LOUW, AND POETS.

2. Discussion of Results given in Table 1.

(a) Explanation of Terms.

It should be mentioned that the terms used in the last column under nature of pasture in the above table will be employed throughout for this type of table and have been selected to designate the follow- ing : All the terms refer to grasses except in the few cases where “ shrub " has been inserted. A grass consisting of apparently equal quantities of green and mature grass — mature indicating definitely not green — is named “ mixed ”, while a mixture of green and mature grass with one kind definitely predominant is called “ mixed, mainly mature ” or “ mainly green ”, as the case may be. If the sample consists almost exclusively of green or mature grass with only a sprinkling of the other, it is called “ mixed, practically all mature or “ green ” according to which grass is almost exclusively present. The remaining terms “ old, dry mature ” and “ green ” are self explanatory.

( b ) Classification of Pasture.

The table given above reveals a number of very interesting points and throws a great deal of light on some of the pasture problems of the Union.

If the description of the pasture for mineral surveys 1 and 2 given in the last column be looked at it is seen that for both periods the grasses varied almost without exception between a mixture of green and mature grasses to one in which mature grasses definitely predominated (i.e. mixed, mainly mature). Mid-winter is in July, when heavy frosts have usually fallen, which would obviously further reduce the small percentage of green pasture if any is present at all, so that the analyses given for pasture in May are probably better than the figures for mid-winter.

The description of the pasture for October, 1931, is not normal for most years. Usually some rains have fallen and young grass has made its appearance so that “ old dry mature ", which often appears in the table under review, should perhaps be less in evidence in order to give a true conception of the usual state of the pasture in mid- spring’. In 1931 a severe drought existed in a number of areas, as is distinctly indicated not only by the description of the pasture but by its chemical composition, and especially by its protein content. If the description of the pasture for the three surveys be taken as a whole, it becomes evident that for May, 1930, May, 1931, and October, 1931, there were very few outstanding differences between the pro- portions of green and mature grasses present and that with few excep- tions the animals had to be content with the less palatable and less nutritious mature pasture in the absence of green feed. It will be interesting to note changes in the state of the pasture for surveys that have been made during other seasons of the year. These results will be published in due course.

(r) Crude Protein, Fibre and Carbohydrate plus Ether Soluble

Extract.

The crude protein content of the grass samples collected during all three surveys was determined, while for the Third Survey, October, 1931, the analysis for fibre and carbohydrates plus ether

513

MINERAL CONTENT AND FEEDING VALUE OF S.A. PASTURES.

soluble extract was also undertaken. The crude fibre content appears to be high and is rarely below 30 per cent., while it remains on an average in the neighbourhood of 40 per cent. The carbohydrate plus ether soluble extract values are round about 55 per cent., and as the latter were invariably found fo be below 5 per cent. — about 20 analyses were made — the carbohydrate fraction of the pasture was about 50 per cent. The values for protein are strikingly low; only in excep- tional cases do the figures reach 10 per cent, while values less than two have been obtained and 3 and 4 per cent, are the rule rather than the exception. It must be remembered that the grasses, as already stated, varied between mixtures of about equal quantities of green and mature on the one hand and old dry mature grass on the other. The crude protein content of the pasture for the periods May, 1930, May and October, 1931, therefore applies to periods of winter grazing anti drought and should not be taken as a general figure for South African grasses. However, the fact remains that growing sheep requir- ing approximately 18 lb. of digestible protein per day and consuming about 2-5 lb. of winter grazing per day would ingest not more than 09 lb. of crude protein on pasture such as most of that given in Table 1. The question of a probable protein deficiency in winter grazing and during early spring, if future surveys during these periods bear out the figures obtained for pasture in May and October, 1931, will be kept in view. It may be added that the nitrogen content of the soils is a good average and on the whole above 05 per cent., a figure usually indicative of the necessity of nitrogen fertilizers.

(d) The Phosphorus Content of Pastures.

The mineral content of the pastures is most striking in some respects. The values for phosphorus are extremely low on the whole and the often recorded fact that the phosphorus content of grasses decreases with the age of the grass has again been noted, mineral surveys one and two (May, 1930, and May, 1931, respectively) show- ing higher values than those obtained in October, 1931, in areas where drought existed, as a glance at Table 2, giving the monthly rainfall will reveal and where as a result no new grass was present. In any case, a comparison between the phosphorus content of the pasture in May and in October is hardly necessary as the figure for winter pasture is already so low in most cases that it denotes the presence of mature grasses mainly. Such a comparison is only in- teresting as it reveals the length of the period in 1931 that stock had to be content with pasture of low feeding value and phosphorus con- tent. The deploring fact remains that in 1931 the pasture showed very little improvement in most areas as far as the phosphorus con- tent was concerned from the beginning of winter until mid-spring. There are some exceptions naturally. Zoutpansberg, area 6, shows a rainfall m Table 2 of about an inch in August and t h phosphorus content of the pasture was 44 per cent, in October instead of the- low value of -lb in May. The figures for area 1 — Middelburg, Transvaal — are not comparable, as different farms were used for the three surveys. Areas 4, 5, 9, 10 show a decided drop and Table 2 shows no rain in spring. Areas 15, Hi, 17 and 18 show high rain- falls, although, except 17, which has had the least rain, the phos- phorus remains low. This observation appears to lend strength to the contention of Van Wyk (1932) that heavy rains rob

544

DU TOIT, MALAN, HOLZAPEEL, LOUW, AND ROETS.

plants of their phosphorus by leaching. Area 20 shows appreciably higher phosphorus in October after a heavy late winter rain. It must be remembered that comparisons are made only where the same farm was used for both the surveys in 1931, while mineral survey 1 in May, 1930, provides an additional figure for a winter survey. A study of the remaining areas continues to show a large number of low values; as a matter of fact, of the total number of 115 analyses made for phosphorus for the three surveys, 72' show a value lower than 2 per cent., while 29 lie between 2 and 4 per cent., and only 14 above the fair average of ’4 per cent. P205. It must be added that in areas 20 (Port Elizabeth), 28 (Albany), 29 (Bedford), fairly high to high values were obtained for phosphorus for all three surveys, and that in practically all cases shrubs which are admittedly higher in phos- phorus than grasses were present in the samples analysed.

( e ) The Phosphorus Content of the Pastures in Relation, to the Phosphorus Content of Soils.

The figures for the available phosphorus in soils with very few exceptions are exceedingly low on the whole. Values lower than approximately -005 per cent, are taken to indicate phosphorus defi- ciency, and it is interesting to note that the three areas 20, 28 and 29 mentioned above (where high values for P205 in pasture were obtained) are all, except one (where only one survey was made) well above the borderline of phosphorus deficiency. Area 0 (Zoutpansberg, Transvaal) shows very high available soil phosphorus, although its pasture in May, 1931, was very low. A correlation of the phosphorus content of the soil and the pasture can hardly be expected to show in Table 1, except in a very general way, such as extremely low phosphorus in soils generally and low in the herbage on the whole. It is very doubtful whether the phos- phorus content of the pasture collected at various stages of growth, growing on different types of soil, subjected to different climatic conditions and not composed of the same kinds of grasses, will show any correlation with the phosphorus content of the soil.

At all events such a correlation is not apparent from a study of Table 1, except in the few areas already mentioned, where high soil phosphorus apparently resulted in a high figure for phosphorus in pasture. To complete the list all the areas showing enough soil plios- phonis (i.e. above 005 per cent.), except No. 6, could be added. In all cases fairly high to high values were obtained for the phosphorus content of the pasture. The exception — area No. 0 — is interesting in that for the third survey the correlation between high phosphorus in the soil and high phosphorus in the pasture does exist but not for the second survey, when, incidentally, the pasture consisted almost exclusively of mature grasses low in phosphorus. The stage of growth of plants, which is determined to a large extent by climatic conditions, is undoubtedly an important factor in determining their phosphorus centent, for it is seen in Table 1 that green pasture in- variably shows a satisfactory value for phosphorus independent of the phosphorus content of the soil. Furthermore, a perusal of the results showing low soil phosphorus, i.e. below -005 per cent., indicates that values of phosphorus in the pasture vary from extremely low figures,

545

MINERAL CONTENT AND FEEDING VALUE OF S.A. PASTURES.

viz., 07 per cent for mature and old dry grasses to medium and high values, viz., -46 per cent, for green pasture. The phosphorus content of the herbage in these cases apparently bears no relation to the soil phosphorus.

In conclusion it may be added that it is not the intention to prove an existing correlation between the phosphorus content of soils and the pasture growing upon them from the figures presented in Table 1. For that purpose climatic conditions, stage of growth and differences in plant species would have to be equalized, which obviously could not have happened in the results under discussion. The main issue, however, remains that the soil analyses provide proof of an acute phosphorus deficiency in most areas, while the pasture analyses largely corroborate this view with the indication that climatic con- ditions and stage of growth are factors which influence very largely or may even completely change the picture of' the phosphorus content of the pastures.

The possibility of a correlation of the results of' soil analyses with those of pasture and blood analyses are dealt with from a different angle on pag*e 569.

(/) CaO, MgO, K20, Na20, and Cl.

Compared with European figures the calcium content of' South African pastures in winter and spring, 1931, were low. Even soils high in calcium apparently had little effect on the calcium con- tent of' the herbage. For instance, pasture on a soil containing 4 per cent. CaO showed 41 per cent. CaO, whereas one on a soil con- taining only -078 per cent, showed 44 per cent. CaO. There appears to be less variation in the calcium content of the pasture of different ages, although it must be added that the values taken at random are considerably more constant than in the case of' phosphorus. The calcium content of shrubs, like their phosphorus content, is higher generally than in grasses. Emphasis must be laid again on the fact that the analyses represent pastures during the driest and least abun- dant season when the feeding value and quality are at their lowest as a consideration of the protein content reveals. It would be better to stress the length of time that only poor pasture was available in 1931 than the unfavourable comparison of these figures with the values given by Orr (1929) for cultivated or even “ all grazed natural pasture as the figures given in Table 1 represent the compo- sition mainly of' fully grown mature pasture which is admittedly less nutritious than younger herbage or even than the portion which would be selected by the grazing animal.

The values for magnesium given in Table 1 require little com- ment as quite a fair average is apparently maintained even in old mature herbage. The amount is probably more than sufficient in all cases for the animals’ need. The values lie between Tl and ‘32 for grasses, while a few higher figures in samples consisting of a mixture of grasses and shrubs Avere obtained.

Potassium varies between -22 and 245 in pastures with an average round about 1 per cent., while the available potassium in soils does not show anything like the variation that the lime content does.

546

RAINFALL IN INCHES. February -September, 1931.

DU TOIT, MALAN, HOLZAPFEL, LOUW, AND ROETS.

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547

MINERAL CONTENT AND FEEDING VALUE OF S.A. PASTURES.

It appears that the potassium content of grasses decreases with age, although the values for soil potassium in areas 28 and 29 tend to show a distinct correlation between high soil potassium with high pasture values. However, this correlation is imperfect for low soil potassium shows high values in pastures in a number of instances, although the opposite has not been observed in a single case.

Sodium in pasture appears to vary without regard to the sodium content of the soil, although it does seem to decrease definitely with the age of the grass. The wide variation in the sodium content of pastures is noteworthy, values as low as -01 per cent, having been obtained, while 3 is not uncommon and several high values round about 7 have been registered.

The remaining element, viz., chlorine, shows great variation both in soils and in pasture. Here again the chlorine content of pasture is seen to decrease definitely with the age of the plant. The few figures available in Table 1 for chlorine in green pasture are all high, while old dry mature grass shows greatly decreased values.

Finally, it must be mentioned that the herbage of which the chemical composition is present in Table 1 obviously does not neces- sarily represent the portion actually eaten by animals, for it is known that certain parts are grazed in preference to others, especially during winter, when grazing is mainly mature and frequently hard and fibrous.

Discussion .

A glance at Table >3 indicates wide variations in the chemical composition of the same species from different areas, while the last column of the table shows that the individual species were analysed at various stages of growth. In other words, climatic conditions, in- cluding differences in soil conditions, produced different stages of growth in the same species, causing in their turn variations in the chemical composition of such species. Species one — Themeda triandra — shows samples consisting mainly of' green grass on the one hand and practically all mature on the other. The major proportion of the samples were composed of mature grasses, due to lateness of the time of' sampling — May, 19-31 — and, as the description of the samples in the last column reveals, with generally low values for P, Xa, chlorine and protein. The same grass — Xo. 10 in the table — in October, 1931, was obtained from 5 of the areas included in the May survey, and a comparison of the chemical composition at the two periods is interesting: —

Locality.	Survey.	p2o5.	CaO.	MgO.	K20.	Na20.	Cl.	Protein.
Petersburg . . .	2	•14	•24	•12	■71		■20	2-1
	3	• 14	•28	•12	•48	•01	13	2-0
Potchefstroom.	2	•11	•36	•25	•74	—	■18	21
	3	•07	■ 17	•07	•31	■01	•06	2*9!
Kokstad	2	•18	■28	•13	• 75	—	• 16	3-9
	3	• 16	•38	•26	•59	—	•19	3-7
Kroonstad. . . .	2	•3	•31	■08	•81	—	■ 16	2-5
	3	• 12	•24	• 16	•44	—	•04	9.9
Ermelo	2	• 11	•36	—	•71	—	•19	2-4
	3	■3	•34	•24	1-23	—	•36	8-1

548

SURVEY II, MAY, 1931.

DU TOIT, MAI.AN, HOLZAPFEL, LOUW, AND POETS.

3. The Chemical Composition of the same Species of Grasses from Different Areas.

£	Mixed i Mixed, Mixed, Mixed, Mixed, Mixed, Mixed. Mixed, Mixed, Mixed, Mixed, Mixed. Mixed.	Mixed, Mixed, Mixed, Mixed. Mixed, Mixed. Mixed, Mixed.
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MINERAL CONTENT AND FEEDING VALLE OF S.A. PASTURES.

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		J)U TOIT, MALAN	HOI.ZAPPEL, LOl’W, AND ROETS.
Nature of Grass.	Mixed. Mixed, practically all mature. Mature.	Mixed, mainly mature. Mixed, mainly mature. Mixed, practically all mature. Mixed, mainly mature. Mixed, mainly mature. Mixed, practically all mature.		Nature of Grass.	Mature.	Mixed, practically all mature. Old, mature. Old, mature. Mixed, practically all mature. Mixed, mainly mature, Old, mature. Green. Mixed, mainly mature. Mixed. Mixed. Old, mature. Mixed, practically all mature. Mixed, mainly mature. Mixed, mainly mature. Green.
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Locality.	Zulu National Training Inst., Nongoma Glen Shields, Bloemfontein . . Elandskraal, Pretoria	Zeekoegat, Pinetown Lots Nos. 45/48, Entumeni, Eshowe Melbourne, Port Shepstone. . Hartebeest, Worcester Woodlands, Bathurst Leliefontein No. 25 Ermelo..		Locality.	Hartebeestfontein, Krugers- dorp	Barberton Kaalplaats, Marico Gemsbokpan, Mafeking Derby No. 56, Piet Retief.. Wildebeestfontein, Peters- burg Mimosa Park, Potchefstroom Rock Dale, Kingwilliamstown Koppieskraal, Kokstad Mimosa Farm, Umtata Primstone, Bedford Greefputs, Barkly West Glen Shields, Bloemfontein.. Naseby Thorns, Kroonstad . . The Outlook, Bethlehem.... Leliefontein, Ermelo
Species.	Chloris virqata	A ristida junciformis		Species.	Themeda triandra..

551

MINERAL CONTENT AND FEEDING VALVE OF S.A.

PASTURES.

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1			5

DU TOIT, MALAN, HOLZAPFEL, LOUW, AND POETS.

The essential facts observed in Table 1 again stand out: —

(1) In all cases except Ermelo when the sample consisted of green grass entirely, the phosphorus content of the pasture decreased from May to October, i.e. as the pasture became older, for drought existed and no new growth took place.

(2) K, Na, Cl, and to a less extent protein, show the same

decrease in values from May to October.

(3) Calcium and magnesium showed variations, but no definite drop or rise.

(4) Ermelo grass in October was quite green and showed an

increase for K, Na, Cl and protein when compared with the analyses in May.

It appears that climate is the determining factor of a poor analysis or otherwise of a species of grass collected from several areas, which means that it has grown under different conditions. Rain or drought largely determines the stage of growth at any particular period, which in its turn determines the composition as regards P, K, Na, Cl and protein.

The composition of species No. 2 — H yparrhenia liirta — shows a number of similarities to Themeda triandra. The samples analysed were practically all mature and the values for P, K, Na, Cl and protein even lower than for Themeda triandra. Both high and low values for phosphorus were obtained for Panicum maximum. As a matter of fact the analyses of this species from all four areas indicate that it compares favourably in composition with other grasses given in the table. On the whole it must be said that with the exception of Pameum maximum and the shrub Chrysocoma tenu i folia the grasses given in Table 2 reveal very poor winter feeding. The analyses for October, 1931, largely corroborate this view, and it will be interesting to follow the seasonal composition of these grasses for later surveys.

553

MINERAL SURVEY IT. MAY, 1931.

MINERAL CONTENT AND FEEDING VALUE OF S.A. PASTURES.

4. The Chemical Composition of Different Species of Grasses from the Same Area.

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554

DU TOIT, MALAN, HOLZAPEEL, LOUW, AND POETS.

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1	20 § 2 * 2	l> .1 o ^	20 15 10 22	C1OC0	1(5 25 •12	sss	332
o o o o o	oooo-o	O O O O	O O o	o o o	O' o d	O o
0	oi ?! ?! oi cc	3?!£23	5nn«;	<M Ol CO	3 2 3	322	233
6	o o o o o	o o o o o	6 O O' o	6 O o	6 6 6	O O '	— 1 O o
o	-H X C C. -H		zzuz	2 2?!	3 ?! L'	3 §	233
	© © o o ©	00000	O O' O' 6	000	O' o o	d O' o	O O O
Species.	Cymbopogon validus Eragrostis nebulosa Digitaria species A ristida junciformis Hyparrhenia hirta	Hyparrhenia hirta Digitaria species Cynodon dactylon Sporobolus indibus Themeda triandra	Digit a ria s pecies Aristida barbicollis Eragrostis micrantha. . . . Cynndon dactylon	A ristida junciformis Eragrostis plana Themeda triandra	Pentzia incana (Sensii Eat.) Chrysocoma tenuifolia . . . Eragrostis atherstonei . . . .	Panicum maximum Chrysocoma tenuifolia... Pentzia incana (Sensii Lat.)	Cussonia species Portnlacaria affra Themeda triandra
Area. ...	Lots Nos. 45/48, Entu- meni, Eshowe	Mimosa, Umtata	ft i= •2 * £ o S	Woodlands, Bathurst..	Allandale, Middelburg, C.P.	Kingston, Albany

555

MINERAL CONTENT AND FEEDING VALLE OF S.A. PASTURES.

Mixed. Mixed, mainly mature. Mixed, practically mature. Mixed, mainly mature. Mixed, mainly green. Mixed, practically all mature. Mixed, mainly mature. Mature.	Mixed, mainly mature. Shrubs. Mixed. Mixed, practically all mature.	Mixed. Mixed. Mixed, mainly mature.	Mixed. Mixed, practically all n.atuie. Mixed, mainly mature. Mixed, mainly mature. Mixed, practically all mature.	Mixed, practically all mature. Mixed, practically all mature. Mixed. Mixed, mainly mature.	Mixed, mainly mature. Mixed, mainly mature. Mature. Mixed, practically all mature. Mixed, practically all mature.
O t'- CO CO CO 04 CO	HO 10 0 CO	0 0 uo	00 CO 0 00	GO CO ^ O	C5 pH CO lO t'"
COCOCO*OCO^HO^	CO CO >0 CO	CO CO 04	^ CO co 10 CO	CO ■’■f 04 0 4	CO Tt 10
aGOQOcuoa^io	lOCOi-^	04 O O	t'- t" 03 IO 00	O i-G O X	— 1 co r- ho O
04 O O 04 04 0 0	-+ ,-H	lO t}i ^	O P-H O ^ ^	04 O 1—1 O	O '-t O' co 10
00000000	0660	OOO	OOOOO	0000	O fl O O
C'lHh.iflcOt'OOCO	-t 04	HO I> O	GO CO CO CO	O I-H O CO	O ■— * O Tj* t"
CO^O— • 04 O O O	® 1 1 «	CO 04 O	— 1 O O *1 O	OIOhO	rf HO 04 rf
cooooocc	0 0	OOO	OOOOO	OOOO	O' 0 6 0 0
___	0 00	LO -H —	0 ■>* r~ — 1 0	0.10 0 0	GO •■+ 00 -— ' ■+
C0C00',t''— iHOiOHO	X lO l"	10 CO 00	0 0 I> !-<	1— l CO t> rft	O OC GO CO HO
’—'OO'— iOOO	O Cl O H		^ P-H O ^ O	f-i 0 0 0	CO H 01 H 01
CO lO CO Cl Cl 00 i'*	XOMO	i> oc	r - co Cl O	10 co	CO 00
CImX^hOhO	Ol 10 04 ■— <	1 -?	•—i 00 CO 1—4	? 1 1 71	1 1 1
00000000	O O O O	0 0	0000 0 •	0 0	0 0
05 ^ Cl Oi ’t 00 t- -H		XX -H		l''* 00 CO CO	04 CO CO 40 CO
04 CO 04 04 Ol 04 01 04	04 CG CO CO	04 CO CO	-H 10 to 10	10 co CO	CO co CO CO CO
00000000	0000		OOOOO	OOOO	OOOOO
ClOJ-fCC^	..	0 01 0	CO T* 00	X CO -"t	— 1 t" 4 CO CO
COO»-H^H<Mr-H^^H	04 L- CO CO	CO CO CO	— 1 _ 1— 1 f— 1	1 si .-H	^ 04 CO • HO
OOOOOOOO	■0 ■0 •0 ■0	= 00 1	OOOOO	OOOO	OOOOO

'"3

a.. 2 „

§ £ -Si? "S.5-

C.JS 3 ?

; § £ 2 § r§ ^

1 >■* 5 S v. 2 5 : Oa-jS O ! C Ch $5 $ -< T-

V» ‘ ~ O ^ *s

, K] C; ft, 65 Gr ~T\

i

r-<5 ■;

•S>8^'

St, ^

-d ^ oj 2 O -2

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s.l°

. » 5s S

.QO(

556

Panicum maximum

Table 4 — (continued).

DU TOIT, MALAN, HOLZAPFEL, LOTJW, AND ROETS.

||

ci ci

a a

g ^ >**>

'"cS c3

>> o o _o

3 O O 3

o; c ^ l!

9 Ph Oh Oh

'd'd ^ £ '■3 ra § 0) a) 3 P 0 o 3

.2 .£ te "5 .2 .2 3 S § S S § S 3

^ Tt< Tt< co tj< oo

N N N H M H

O O O O O O O

^ O CO M ^ ^ I'

^ MN 10 H 00 ICIOO^ co co co

6660600

P-H _H CO <-H r-H H O

6066666

^ 10 00 04 05 00 O CO CO 40 04 04 CO 01

0666066

0000000

	! § • I
• "5	; gi ; :
: §	! 0 • ‘
a'S

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0h ”*o 8h >4J o »> >5 O C: O

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2; -C- O &5 ?55 W

^ 5 &J c 8 C ^5

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£h O ^ ^ Eh

9 9

.2 .2 3 3

CO CO CO CO

co o

^ 04

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CO CO

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9 9

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a a.

o r- co ^ CO 04

CO CO CO — ~0

5 5 5

a d d

9 9 9

>>>? 5j 5 5 5

cc cs C3

a a a

lOiOOh CO 04 04 04

OO OOO OO OO 6 I O'

f 9

•2

0^5

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r3 G T3

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0 4 CO HO1C0

9 9 3,

6 ro to

GO 04 O O l <“ H I -

6 6 6

co oj o o

0000

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0060

10 co GO OOO

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-H O F-.

066

o o © ©

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h ii o OOO

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<0 <0

f- t-.

00

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6 6

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6 6

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pH 04

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co co

6 6

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20

557

MINERAL CONTENT AND FEEDING VALUE OF S.A. PASTURES.

558

DU TOIL’, MALAN, HOLZAPFEL, LOUW, AND ROETS.

Discussion.

Table 4 is very interesting as the composition of the various species collected in one area have been subject to the same conditions of climate and soil fertility and are, therefore, more strictly com- parable. The difference in chemical composition between a number of species from the same area is therefore due chiefly to natural dif- ferences among; the species themselves, such as more leaf formation, high in phosphorus in one species, e.g. Panicum maximum, Themeda triandra, etc., as against excess stalk formation of poor analyses in the other, e.g. Aristida congesta. Furthermore, grasses show dif- ferences in the rate of growth, some being early and others late varieties. Some are better drought resisters than others or show better growth on a poor soil. The effects of these combined factors, grouped under characteristics of species, on the chemical composition of grasses must be borne in mind when considering Table 4.

Panicum maximum was collected in four different areas in May, 1931. In three cases its analyses were quite the best and, in the fourth its phosphorus content was still the highest, the rest of its composition excellent, but there was little to choose between it and some of the other species. Apparently Panicum. maximum- — “ buffel gras ” — produced excellent winter grazing in 1931.

Cynodon dactylon — “ kweek ” — although its chemical composi- tion is definitely not on a par with the species just mentioned, also shows quite fail' analyses and good winter grazing. Themeda triandra — “ rooi gras ” — one of the commonest grasses and collected from about twenty areas, was low to medium in phosphorus in May, 1931, and leaves much to be desired as winter grazing. Other species could be selected, but it will be more interesting to compare the chemical compositions at a later date when the analyses at other seasons are available.

5. Inorganic Phosphorus in the Blood.

The samples of precipitated blood sent in from the field as stated earlier in this publication, were analysed for inorganic phosphorus on arrival. The results of the analyses are given in Table 5.

Discussion.

The most important factor in Table 5, apart from the values for phosphorus, is undoubtedly the period of' hydrolysis. Provisionally the increase due to hydrolysis will be considered on the following basis. Values for inorganic phosphorus after 24 hours hydrolysis will be regarded as 10 per cent, above the true value, after two days 20 per cent., and beyond that time more than 20 per cent. Data will be presented on this phase of the work in the near future. It may only be added that judging from the figures obtained so far the difficulty of deriving at true values owing to the hydrolytic factor, will be completely removed.

559

INORGANIC PHOSPHORUS GIVEN IN MGM. per 100 c.c. BLOOD.

MINERAL CONTENT AND FEEDING VALUE OF S.A. PASTURES.

a! ° ■

Ph

Ph :

1 Pn <t; ;

O X O M cr >H O P h-5

»o co io co

^ rf ' r « « O S ft

o •' o . o

*3 *3 ^ +3

O 0) o o o O O O o

p ^ cc s «

CO O Ol O T* Tt<

'-H Ol CO ^ ic

X X

1— 0 c- io co cc

o V

■3 £ bC o

be o

”§ a

560

Table 5 — (continued).

DU TOITj MALAN, HOLZAPFEL, LOUW, AND POETS.

4- O

^ OH cC

£ ia

X

o 3 To X

c o u 5

g-.-a ao.g °o«< X <5 S

W (N CO CO 4

■f g a

1^11

00 CO O 05

^ co co co jo

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^ o

£ W

o o o o

;>> >i >■„

P-t S-.f-.S-i

£ £ £ o o o J o o o

>> ^ . Ph Ph

QPO

LO

X Ph'

^ (X ^ CO JO

1 Ol CO Th JO

i <N CO ^ JO

■ £ £

d jj?

yZ 1> ^ bjj

<L>

c

S.SP

.O O

o o

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CO CO JO r— I CO TT CO

t^ocio JO CO CO

I <M CO ^ LO

I 0-1 CO rh JO

561

Inorganic Period

District. Farm. _^osphorus Description of Animals. Hydrolysis

MINERAL CONTENT AND DEEDING VALLE OF 8. A. PASTURES

10 CO d Cl CO

>1 O >> t>i U c- ^ fH

PhlQflQ

CO Cl ^ CO CO CO CO Cl

I Cl CO ^ *o

s

ci hP

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a a

<D

0? >»

£ O

C l 00 10 CO «o -+

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co a a>

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: g oi j* £

; O p O

» ° p ° °

' >j <D >» tC.

Cl O CO o Cl CO CO ^

Cl CO ^ *0

£ £ £

^ CU' - CO CO CO CO

— < Cl CO ^ lO

562

Lactating cows

Table 5 — ( continued ).

DU TOIT, MALAN, HOLZAPFEL, LOUW, AND POETS.

w

5 o i) c =3 bfc.g

S’ % g 3

o 6

£ -a t, ©

^ Oh < 2

CO CO CO ^

0<

'L' ^

>4 ci

*9 ^ ce «c "3

J, ® « C

^ ^ t»> >> ca

CO 00 CO CO OT

P= P= - * £

o O CO CO O

o o ^ ^ o

31C1 O <M O CO ^ ic ^ 1.0

— I O J CO ^ lO

-H Ci Th T* ^ lO

i Ol CO ^ lO

S -S

ego

■ ft ft ft

rti rt^ CO -t

tl) c to? to g e C'“ 3 ft G ^ gft

H JO CO lO co lO CO CO CO CO

GO 01 CO CO '—I ^ Tf lO lO ic

I Ol CO t4< lO

bO M fcO G £ W) G VS O G VS

d °G cj •h> . *3 -+3

o ^ o

S_t O c£

ft ft pH ft

i> o a oi

lO lO LO co

l Ol CO ^ lO

.2fc r

id..

><

C5

56«‘ 3

MINERAL CONTENT AND FEEDING VALUE OF S.A. PASTURES.

P t>>

o PS o ^5

*2 f- c3 2 O fi g _Q bJD.~

oh g 5

2 o 55 <1

^ ^ ^ n

Oh < 2

CO CO CO CO co

t- £ £ £ £

OOhQQ

LO lO o o

uo ^ CO 1C

I Ol CO t* LO

s § 0

^ <M

.«§ $ o

‘53

^ t>D „

SP-S g L .

St ® » c

3 CC -2 rZ <D

o <D 0> C» ><-

^^WKO

H Cl N *«o o

T*1 CD »0 I> CO

PWP

O CO O Th *o ^

I Ol CO '-t io

CO IO CO CO

£ © £

0) >> ^

^co<* £ £ Tjt . P P

.' • o o

a* J S ° °

o 3 S3 >, >,

X 0 0

CO <M I> CO 00 'TjH lO CO CO

t Ol CO to

CO ’t CO CO ^

^ £ £

£ fi c

a as oo oo

' OJ CO IQ

<N £ "Ph

564

Table 5 — (continued).

DU TOIT, MALAN, HOLZAPFEL, LOUW, AND ROETS.

.a

• 2 O

o £ <s

® T3 Q

a

n^nn

i* -2 o o o ce

cd ci

c >>3

r1 t- ct

IQ CO CO ^

£ £

O 05 0> 0>

CW

c C C fl

<1> C' O ■!/

x x x x

COCO

■2 h TO

5Pg«g 5

2 o ^ Oh ^ 2

CO -n IO 1C

CD

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uo CO CO LO CO ^ lO lO

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3 S)3

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565

MINERAL CONTENT AND FEEDING VALUE OF S.A. PASTURES

"d

.2 SH "3

w

CO C'J <M W <M

i O'! CC iO

k

M £ +■>

^ bX)

W M ^

O >> k> k> >>

Ci frn (h fc-. Sh

-JQflflfi

&-0 & & o 6n o ° u c ° ° 5 k> k> f_ o s-< f-« P><PP

-1- .

™-Sa h'J 14

g O >J

X a in

OPP

o 3 0-^

*z3 ^ ce

2 o D fl Pn ce rj

ogS<:

p <1 2

CO W H O CO Tt<

-h x CO CO

^ ^ co »o ^

lOCOrH

l> l> CO »o

a to cc

IO CO

566

Inorganic Period

District. Farm. Survey! AverageTof Description of Animals. Hydrolysis

10 Animals. (Days).

DU TOIT, MALAN, HOLZAPFEL, LOUW, AND POETS.

£ £

CO ^ SO O

co 10 co

t'* Cl PI CO ^ CO

CO HO 00 CO CO

Cl t- o ^ CO CO

ills

rt o o M

i e-l M ^ 10

(5s-

5s

be I

c"5s-£

O ^

3 x) B « ■a i. o a

fl S.S § cn a -g

ills

P s

567

MINERAL CONTENT AND FEEDING VALUE OF S.A. PASTURES.

For the present, therefore, a consideration of the results of Table 5 with the variations in periods of' hydrolysis from 1-6 days and for blood obtained from cattle of different ages will be followed on general lines only. The inorganic phosphorus in the blood of young stock is always definitely higher than that of older stock. Heifers and oxen 2 years old, on phosphorus sufficient pasture, will probably average round about 5 3 mgm. per 100 c.c. blood, according to the values given by Malan, Green and Du Toit (1927), while mature cattle generally would show approximately 3'8 mgm. under the same conditions. The blood of lactating cows is always lower— about 3-2 mgm., while the inorganic phosphorus in the blood of dry cows would be above 32 under conditions of phosphorus sufficiency. For the purpose of comparison, these figures may be taken as stan- dards and allowance made for hydrolysis as suggested above.

A glance at Table 5 reveals that a number of areas from which blood was collected undoubtedly suffered from a marked degree of aphosphorosis. Perhaps most outstanding and obvious are areas 7, 8, 10, 11, 12, 13, 14, 17, etc., i.e. where figures round about 3 have been obtained in spite of hydrolysis which would normally have in- creased the figure after 2 or more days to considerably beyond that value. A more detailed study of the table is interesting. In area 1 the same farm, viz., Roodepoort, No. 8, was selected for only two of the five surveys by the field officer. In October, 1931, young heifers showed a figure of 31 mgm. inorganic phosphorus after 24 hours’ hydrolysis. This figure is undoubtedly indicative of marked aphos- phorosis, while 3-4 mgm. obtained for lactating cows in April, 1932 — i.e. the fifth survey — after 24 hours hydrolysis does not lie far below the normal value. These two sets of figures incidentally bring out another advantage of blood analysis. The donors may suffer from varying degrees of acuteness of phosphorus deficiency, depending on the nature and abundance of the pasture. For instance, it is more than likely that pasture in its early stages of growth even on a soil deficient in phosphorus contains enough phosphorus for the mainte- nance of animals and, may lie, even for optimum growth. At all events, there is no difference in the phosphorus content of the blood of catfle grazing such pasture and in the blood of those receiving in addition a phosphorus supplement. Young succulent grass contains on a soil as deficient in phosphorus as that at Armoedsvlakte in the notoriously deficient Bechuanaland area, approximately -4 per cent. P20s, and as yet there is no reason for believing that such pasture doe's not provide enough phosphorus for animal requirements. However, the point merely is that various degrees of deficiency or even of sufficiency and deficiency may exist during the year or during seasons of poor feeding, such as winter, and on the other hand during seasons of abundant grazing of good quality, as is sometimes the case in summer. Under such conditions the same animals will obviously show a high figure for inorganic phosphorus during the period of abundance and one indicative of aphosphorosis when very poor grazing is available. The two values 31 for young heifers on Roodepoort in area 1 in October, 1931, and of 3 4 for lactating cows on the same farm in April, 1932, suggests such a condition in the area in ques- tion. Areas 2, 3 and 4 may be passed over without comment, but

568

DU TOIT, MALAN, HOLZAPFEL, LOUW, AND POETS.

No. 5 is interesting. On Kaalplaats dry ewes showed 3 8 mgni. in- organic phosphorus in their blood. The owner realizing the signifi- cance, began feeding bone meal, so that the subsequent values signify phosphorus sufficiency, as they are meant to.

The figures given for area (i appear to be normal. Area 9 strongly savours of deficiency. Areas 7, 8, 10, 11, 12, 13, 14, 17 have already been dealt with. The values for areas 15 and 16 if con- sidered in the light of the knowledge that hydrolysis of three days and more had taken place, i.e. the values are most probably more than 20 per cent, too high, all suggest low true values. The same applies to area 18. It is noteworthy how few high values are present throughout the table in spite of the not inconsiderable increase due to hydrolysis.

Area 27 — Cradock Place, Port Elizabeth — shows the type of values that would be anticipated for blood from phosphorus-sufficient areas after several days hydrolysis. Need for more knowledge in the effect of hydrolysis on the inorganic fraction is apparent for a correct interpretation of the results obtained. The results in Table 5 are, therefore, presented provisionally, without further comment, until a more accurate estimate can be made of the increase in the blood of hovines of different classes and ages for varying periods of' hydrolysis under the conditions of the surveys.

All the organic acid soluble phosphorus does not liydrolize to inorganic phosphorus even if the trichloracetic acid solution con- taining the blood he kept indefinitely. Actually, therefore, the rate of hydrolysis of organic acid soluble phosphorus must be determined and, therefore, incidentally, its quantity present in the blood of hovines under conditions of deficiency and sufficiency respectively, after various periods of hydrolysis.

The values for inorganic phosphorus presented in Table 5 are the average of ten. There is quite a fair amount of variation be- tween individual results as will be evident from a study of the figures given in Table 6.

Discussion.

Any individual set of figures presented in Table 6 shows quite a fair amount of variation. It seems, however, that the results of the analyses of samples of blood from 10 animals are sufficient to provide an idea of the phosphorus sufficiency or deficiency of the herd. Both low and high values have been included in the table. It is well to remember where the variation in t lie values are greatest that in most cases the class and ages of the animals selected differ as indicated.

IV. CONCLUDING REMARKS.

1. Correlation of Results Obtained for Phosphorus from Soil, Pasture and Blood Analyses respectively.

The soil analyses presented in Table 1 leave no doubt that there is a marked deficiency of available phosphorus in most South African soils. As a matter of fact the table contains relatively few figures for available P2Os above -005 per cent. A consideration of the phos- phorus content of pastures presented in Tables 1, 3 and 4 conveys the same idea of a great lack of phosphorus in the grazing generally for

569

MINERAL CONTENT AND FEEDING VALUE OF S.A. PASTURES

670

TABLE t> — ( continued ).

DF TOIT, M AI.AN , HOLZAPFEL, LOUW, AN]) HOETS.

J Survey : April. 1932.	► Dry cows (5 days).	% o o &0 C _ -£»	► Dry cows and heifers (3 days)
®00 000»CW(NHIOW	70 Cl CO Cl CO Cl Cl CO CO Cl	00 H CO O *t H Q OO O CO -HCOCOIOCOCOCICOIOIO
Survey : January, 1932.	► Oxen (2 days)	b- Lactating cows (3 days)	► Dry and lactating cows (3 days)
o:> r* 10 co \| ot-oi , CO ^ <C1 CO <N CO CO CO *	OCOOCOhOOhOO ^ ^ 't CO CO CO C l Cl	0X0 0 I Tt-HQOOOOrH Cl CO 1 CO CO cno co
Survey: October, 1931.	>> -5 <N c 45 K o	► Lactating cows (3 days)	► Dry and lactating cows (3 days)
OtNCO-HOO^O^O \| -^COCO-^^IOCOCOCO ‘	HCOCOOh'J’tCOO© ^CO<NCO<NOq<NCOT*CO	OlCS^COOiiOiO^CO \| ^CO(NCO^(NCO '
Survey : May, 1931.	Dry cows. Period ► of hydrolysis (4 days)	Lactating cows. V Period of hydro- lysis (4 days)	Lactating cows. ► Period of hydro- lysis (4 days)
COt'*iHCOOiHCOt>OiCl	05f-il0D»C005C0ClOC0 Cl CO 'C Cl Cl m i* CO	05 d Cl CO 05 Cl 00 CO Cl CO Cl co >o CO co >o Cl CO Cl Cl
a;		1
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m
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671

Area. Sample Survey: May, 1931. Survey : October. 1931. Survey: January, 1932. Survey: April, 1932.

MINERAL CONTENT AND FEEDING VALUE OF S.A. PASTURES.

t^h-C5O500COl>l>COCO

CDiOiOiOCOiOlOCDiOlO

0)^M1C(NL^CDCOOCO

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OOOiMOWCOCO^H^ ^ O IG 1-0 i- LG "O t' to lO

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0^1 O 1G GO CO GO t”* CO O 00

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(M 03 M O 03 t' CO CO N iG 00 03 0010^^0030

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hJ

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572

DU TO IT, MALAN, HOLZAPFEL, LOUW, AND POETS.

the periods mentioned. Here again there are only a few farms where the phosphorus content of the pasture for all three surveys is any- thing like a satisfactory figure. Blood analyses for inorganic phos- phorus provide yet further proof of an almost generalized aphos- phorosis in cattle grazing on the pasture analysed.

It would, therefore, seem necessary to find out to what extent the evidence for a phosphorus deficiency provided by soil or pasture or blood analyses is corroborated when the evidence of the remaining two sets of analyses are considered. In short, does a correlation exist between the values obtained for phosphorus by the three methods employed, viz., soil, pasture and blood analyses? Without reference to the tables it would seem impossible to obtain such a correlation between soil and pasture owing to the variation in the stage of growth of pasture in the areas to be compared. For instance, pasture con- sisting- of' mainly green vegetation growing on a soil very deficient in phosphorus will invariably be higher in its phosphorus content than that on a soil comparatively high in phosphorus but consisting of old mature grass. Areas 20 and (i in Table 1 provide evidence for this statement, as is apparent from the following: —

Locality.	Survey.	Soil P.	Pasture P.	Description.
Area 20	3	•0004	• 46	Green.
Area 6	2	•0431	•16	Mixed, practically all mature.
Area 1	3	•0003	•23	Mixed.
Area 7	1	•00035	•14	Mixed.

These examples could be multiplied from Table 1. At the same time it will be seen that if grasses be selected that are classified in the same category, e.g. mixed, or mixed mainly mature, etc., still no general correlation exists between soil and pasture figures. Here again it must be pointed out that the classification, although serving the very excellent purpose of indicating the state of the pasture, is arbitrary and cannot attempt to define the stage of growth of the pasture exactly. Old pasture in October nearly always contains young shoots and will, therefore, be classed as “ mixed, practically all mature ”, while nearly all pasture that has grown to maturity in late autumn will be classed in the same way. Obviously the stages of growth are different and it is not known definitely how the phosphorus content will vary with the age of the grass. The factors effecting- growth are climatic mainly, and therefore beyond human control, so that theoretically it will be possible to have pasture in practically all stages of growth, and therefore of greatly varying phosphorus con- tent on soils equally deficient or sufficient in phosphorus. In prac- tice, however, seasonal growth limits the variations in stage of growth so that in winter, for instance, one would expect to find mainly mature grasses in most areas, but exceptions to such anticipa- tions must not be regarded as extraordinary. Hence one would anticipate values for phosphorus under approximately similar climatic conditions and for the same season that are comparable in a general way. Comparisons of the available soil phosphorus with

573

MINERAL CONTENT AND FEEDING VALUE OF S.A. PASTURES.

the phosphorus content of pastures must take due regard of climatic conditions in order to have any value at all. Types of soil will obviously affect its water-holding capacity, which in its turn will affect the growth of the pasture, thereby causing a change in its phos- phorus content. In a survey such as that described in this paper all types of soil are dealt with and rainfall varies between wide limits. For the pasture phosphorus to show a close correlation with the soil phosphorus under all these conditions means that the phosphorus deficiency problem is the main one under all conditions of pasture management and determines the phosphorus content of the pasture in spite of differences that may exist in the stage of growth. This contention is obviously incorrect, for, as already said, green grass will invariably show a higher phosphorus content on a soil poor in phos- phorus than old mature grass on a soil comparatively rich in phos- phorus. Comparisons of soil phosphorus have thus been made with the phosphorus in the pasture on general lines and under the three headings : —

(a) low available phosphorus in soil — below 005 per cent. ;

(b) medium available P. in soil -005-01 per cent.

(cl high available P. in soil above 01 per cent.

The three equivalents in pasture have been taken to be —

(а) low, below 30 per cent.

(б) medium, 30--45 per cent.

(c) high, above 45 per cent.

The table of comparison is presented hereunder. It will be noticed that blood analyses have been included. These have been divided into low and high respectively, on the following lines: —

Class of Stock.	True value for Inorg. P.	I.P. after 24 Hours’ Hydrolysis.	I.P. after 48 Hours’ Hydrolysis.	I.P. after more than 2 Days’ Hydrolysis.
Young Cattle	5-3	5-8	6-3	over 6-3
Mature Stock	3-S	4-2	4-6	over 4-6
Lactating Cows	3-2	3-5	3-8	over 3-8

All values in Table 5 le>s than those in the table above for the class of stock in question after the period of hydrolysis stated are designated “ low ", while the rest are “ high ”.

574

DU TOIT, MALAN, HOLZAPEEL, LOUW, AND ROETS.

Table 7. — L. M. H indicate low, medium, and high values respectively. The numbers under Locality refer to those given to the areas in Table 1.

Locality.	Survey.	Soil P.	Pasture P.	Blood P.
1	2, 3	L L	L L	H L
2	1. 3	L L	L L	L H
	1, 3	H M	H L	H H
4	1. 3, 3	L H L	L M L	H L H
5	1. 3. 3	L L L	LLL	LLL
(i	2. 3	H H	L H	L H
7	1, 2	L L	L L	L L
8	2, 3	L L	L L	L L
il	1. 2. 3	L L L	L L L	L L L
10	1. 2, 3	L L L	LLL	L L L
11	2	M	L	L
12	2	L	L	L
	1. 2, 3	L L L	LLL	LLL
14	1. 2. 3.	L L L	L L L	L L L
15	1. 2. 3	L L L	L L L	LLL
16	1. 2. 3	L L L	L L L	LLL
17	1. 2, 3	L L L	L L M	L L H
18	2, 3	L L	L L	L L
20	1. 2. 3	L L L	L L H	LLL
21	1. 2, 3	L L L	L L L	L L L
23	1. 2. 3	L L L	LLL	LLL
24	1. 3	L L	L L	L L
25	1. 2, 3	L L L	H M L	H H L
26	2	M	H	H
27	1. 2	L L	L L	L L
28	1. 2, 3	M H H	M H M	H H H
29	1. 2, 3	H M M	H M H	L H L
30	2	H	H	H
31	2	L	L	L
32	1, 2	H L	L M	H H
33	2	L	M	H

Discussion of Table 7.

A glance at Table 7 reveals the fact that in several cases a correlation between soil and pasture values can hardly be said to exist. In some instances the explanation is at hand — different stages of growth of the pasture — as a glance at Table 1 will reveal. For instance, in area 3, third survey, the pasture grown on a soil, medium in phosphorus, showed a low figure for phosphorus, but consisted of old dry mature grass. In area 4 a high soil phosphorus produced grass just below the high margin, lienee the designation medium.

The two anomalies in areas 17 and 20 are due to the fact, accord- ing to Table 1, that the pasture was green in both cases and, there- fore. medium to high in phosphorus although growing on soil of low phosphorus content. On the whole, however, the correlation between soil and pasture values is remarkable. It must be remembered, that the periods under consideration — May, 1930, May and October, 1931 — being those of poor feeding on account of winter and drought in a number of' areas and as practically no new growth existed, favoured low values for phosphorus in pasture, thereby more easily establish- ing a correlation with low values for soil phosphorus. A comparison

575

MINERAL CONTENT AND FEEDING VALUE OF S.A. PASTURES.

between these two sets of values in summer will be interesting when mainly green grasses are present and stage of growth probably the important factor which will determine the phosphorus content of the pasture. A correlation under those conditions can hardly be expected to exist.

2. Comparison of the Three Methods of Studying Phosphorus

Deficiency.

The values for blood phosphorus agree remarkably well with those for pasture if the difficulty of obtaining for analysis repre- sentative samples of pastures actually eaten by stock be borne in mind. Then, too, there is the period of hydrolysis in the trichlo- racetic acid solutions of the blood which considerably complicates the result. Still, a correlation of pasture with blood values with g‘ood technique is practically a certainty and these two methods of studying the problem of phosphorus deficiency in livestock, i.e. blood and pasture analyses respectively, have the advantage over soil analysis in that they deal directly with the animal or with its food, provided human attempts to select from the pasture samples of the grazing “ eaten ” by stock are successful. In laboratory experi- ments, where the intake of phosphorus is known and can be controlled, a direct relation is brought about within a few days and continues to exist between a low phosphorus intake and low inorganic phos- phorus in the blood. The same relation holds on Armoedsvlakte pas- ture poor in phosphorus as a glance at the figures for inorganic phosphorus in the blood given by Malan, Green and Du Toit (1927) and Malan and Bekker (1930) will reveal. In spite of a low phos- phorus content of Ike soil, figures for phosphorus in the pastures will be high at certain seasons of the year when abundant green growth is available and it is just at this period that a correlation of soil values with pasture values will most probably fail, as several results in Table 7 suggest. Blood values for phosphorus on the other hand will rise and fall with a greater and a decreased phosphorus intake respectively. It is for the obvious reason that blood analyses throw light upon the phosphorus equilibrium in the animal body and en- tails very little labour and, therefore, holds a not inconsiderable advantage over soil and pasture analyses that this phase of the work is rapidly extending and will again be reported on in the near future.

V. SUMMARY.

1. An account of the work done since March, 1930, on the study of mineral deficiencies in South African pastures is presented.

2. The problem is being studied from three aspects, viz., soil, pasture, and blood analyses, although the last method applies only to phosphorus at present.

3. Phosphorus, calcium, magnesium, sodium, potassium, chlorine, fibre, crude protein and carbohydrate plus fat are included in the analyses of the pasture.

4. Surveys, which entail the sending in of samples of soil, pas- ture and blood by about 40 Government field veterinary officers, are carried out at the four seasons of the year, while provision has been made for the analyses of blood samples at more frequent intervals.

•37G

MJ TO IT, MAI.AN, HOLZAPEEL, LOUW, AN]) POETS.

5. The plan of the work includes a study as outlined above on samples obtained from the same area for each survey for the first few years in order to find the main effects of climatic conditions, such as a variation of rainfall on the composition of soil, pasture and blood, before any other areas are included.

0. Blood samples are drawn from mature cattle preferably, trichloracetic acid added to precipitate the blood proteins, and to prevent decomposition, then forwarded to Onderstepoort and analysed for inorganic phosphorus on arrival.

7. Species of grass samples are sent in separately ; these are iden- tified and classified as green, mature, mixed, mixed mainly mature or green, mixed — practically all mature or green, and old respectively, before analysis.

8. The probable correlation of' values obtained by the three methods employed — soil, pasture and blood analyses respectively — is discussed.

9. Stage of' growth undoubtedly plays a very important part in determining the chemical composition of pasture. Hence plot ex- periments have been begun where a number of grass species have been planted in separate plots and are analysed at regular intervals. In addition, these plots provide material at any stage of growth decided upon for the determination of the differential distribution of minerals, etc., in plants.

ACKNOWLEDGMENTS.

The writers gratefully acknowledge the co-operation of the field veterinary officers and the assistance of the farmers in this under- taking.

REFERENCES.

HETCHEON, J). (1895-1903). Report of the Colonial Veterinary Surgeon. Cape of Good Hope.

JURITZ. C. F. (1910). A Study of the Agricultural Soils of the Cape Colony. Publ. Cope Times, Ltd.

MALAN, A. I. (1930). The Increase of Inorganic Phosphorus due to Hydrolysis in Solutions of Blood. 1 6th Dept. Dir. of Vety. Serv., pp. 287-292. MALAN, A. I., and BEKKER, J. G. (1931). Inorganic Phosphorus in the Blood of Pregnant Heifers. 17 th Dept. Dir. of Vety. Serv. mid Anim. Indust., pp. 433-438.

MALAN, A. I.; GREEN, H. H. ; and DU TOIL, P. J. (1928). Coniposition of Bovine Blood on Phosphorus Deficient Pasture. Jid. Agric. Sc., Vol. 18, pp. 376-383.

MALAN, A. I., and VAN DER L1NGEN, G. W. B. (1931). The Micro- determination of Some Inorganic Elements in Blood and Vegetation. 17 th Dept. Dir. of Vety. Serv. and Anim. Indust., pp. 443-452.

ORR, J. B. (1929). Minerals in Pastures. Publ. H. K. Lewis A Co., London. STAPLES and TAYLOR (1926-30). Studies in Veld Management. Sr. Dull. Nos. 49 .and 91, Union Dept, of Agric.

STAPLETON KT AT,. (1927/32). Welsh Plant Breeding Station, Aberystwyth Series.

STEENKAMP, J. L. (1930). Micro-chemical Analysis of Soils. Proceedings and Papers of the Second International Congress of Soil Science. Moscow, 1930.

VAN WYK, D. J. R. (1932). Feeding Value of Grasses. Public Lecture at Meeting of Chemical Institute, Pretoria.

WOOD, T. B. (1911). A Course of Practical Work in Agricultural Chemistry for Senior Students. Cambridge University Press.

WOODMAN, H. E., ET AL. (1926-1932). Series on the Nutritive Value of Pasture. Jnl. Agric. Sc.

577

lSlh Report of the Director of Veterinary Services and Animal Industry , In ion of South Africa , August, 1932.

Cystine and Sulphur Content of Bushes and Grasses in a Karroid Area (Fauresmith).

By M. HENRICI, Ph.D., D.Sc., Division of Plant Industry, Yeld Reserve, Fauresmith.

The present paper is the outcome of a query put to the author by the Director of Veterinary Services of the Union as to whether the leaves of plants contain cystine to any large extent, the question being- prompted by Brailsford Robertson’s 1929 Report of the Work of the Animal Husbandry Division of the Commonwealth of Australia, which mentions that cystine cannot be built up by the animal body but must be supplied by the plant food. At the time literature on the subject was very limited, and it was therefore decided to investigate the point, more particularly on the indigenous bushes of the Fauresmith area.

During the course of the work, Aitken’s (1930) paper appeared, based also on Robertson's report, and after the experimental part had been completed, Evans’s paper (1931) confirmed Aitken’s results for England. Both these papers deal with grasses; the results of the two investigations will be discussed later on.

The Fauresmith laboratory is situated in the S.W. Free State at an altitude of 4,700 feet, on the slope of a kopje facing east. The soil of the Reserve is shallow, sandy, the sand being rather coarse, and poor in nitrogen. The pH value shows it to be alkaline, but it is not “ brak ”, although a number of boreholes in the near neighbourhood yield brak water.

A full description of the meteorological and edaphic features of Fauresmith will be given in a later paper. Here only the following will be mentioned: —

The average yearly rainfall on the Reserve is 1325 in. or 34-45 cm. There are two rainy periods, the earlier falling somewhat irregularly in the months September to December and the second from January to March.

The rain often falls in heavy gushes, causing a lot of erosion; on the other hand dry storms with little or no rain are frequent especially in the spring and early summer. The period from April to the end of September is very dry, and even in the “rainy ” season long dry spells are frequently encountered. The evaporation is increased by strong winds especially from August to November. The temperature range is wide, very high temperatures oceuring from September to March, and very low, will) heavy frosts, in the winter. Even during the summer months it may happen that the temperature falls nearly to freezing point, following a day with a maximum of

35° (C).

679

CYSTINE AND SULPHUR CONTENT OF BUSHES AND GRASSES.

Material Used.

The following' plants were tested for cystine : SaJsola aphylla, Salsola glabrescens, Atriplex nummttlaria, Atriplex capensis, Tetra- gonia arhuscula, Mesemhriantheminn lmmatuvi, Digitaria eriantha var. stolon if era and Eragrostis, cur ml a var. conferta for the season 1929/30 and Euryops multi fid as, Tripteris pachypteris, Pentzia incana forma and Chloris gayana for the season 1930/31.

A few samples from other habitats were also tested — a stolo- niferous Digitaria from Malmani Oog (W. Transvaal) and some Namaqualand plants characterised by a high sulphur content.

Plants are sampled regularly at ihe Reserve, at monthly intervals over thirteen months, so that (air dried) material was available for a systematic investigation of the seasonal variations, if any, in the cystine content.

Method for Cystine Determination.

Different methods were first tried to make quite sure that an eventual negative result was not due to an unsuitable extraction.

A first extraction was based on the method of Sasaki (cited from Abderhalden II. p. 575) by extracting finely ground plant leaves with alkaline alcohol and precipitating the protein by neutralisation with HC1. The sulphur content of the precipitated protein was determined gravimetrically. As it appeared that the amounts were very small, the method was abandoned and a method was worked out, based on the method of determining cystine in wool. It may be mentioned here that the two methods gave the same results. The method finally adopted was the following: — 100 gm. of finely ground air dried plant material was digested in a 1,000 c.c. Pyrex flask with 500 c.c. 20 per cent, hydrochloric acid (111) for at least 8 hours on an electrical sandbath under a reflux cooler. At the beginning the digestion was extended to 20 hours, but it soon appeared that the same results were obtained with the shorter digestion. After that time the contents of the flask were filtered through a large Schleicher & Schiill paper Ao. 597. The liquid as well as the undissolved plant material were very dark coloured. After a thorough washing with hot water, the residue was rejected; in some cases a sulphur-determination was done on it. About 25-30 gm. of black residue was obtained. The solution was if necessary evaporated to a smaller volume, cooled, and under cooling in ice-water, solid caustic soda added until pH4 was reached. Rromphenolblue was used as indicator and did excellent service in spite of the solutions being so dark. Congo red which is recommended in several handbooks, was not found as satisfactory. Towards pH4 a brown precipitate came down. 20 c.c. Acetic acid was then added, care being taken that the pH did not rise above 4. This solution was left standing for several days, during hot weather in a Frigidaire, and the precipitate then filtered off, the liquid being discarded. Some determinations of sulphur were done on the liquid, and it was often tested with lead acetate in alkaline solutions to make sure that no cystine was left behind, although as Evans (1931) points out, this

580

M. IIENRICI.

test, which is recommended in biochemistry handbooks, is ambiguous, other organic sulphur compounds also precipitating lead sulphide under the circumstances. The same impression was obtained in the present work, when although small amounts of lead sulphide were obtained, no more cystine could be obtained from the solution by any chemical means.

The precipitate was dissolved in 5 per cent. HC1, boiled up, and about a teaspoonful of charcoal added, which was generally sufficient to decolorize the solution immediately, the charcoal being then filtered off. The solution was then treated with strong Ammonia (1:1 by vol.), a voluminous white precipitate coining down towards pH4. Bromphenolhlue was again used as indicator. Acetic acid was again added, the pH being kept below 4'5. After some hours a crystalline looking precipitate settled and was filtered off. The solution was then if necessary evaporated to a small volume, alcohol added, and allowed to stand a few days in the Frigidaire; generally a second small precipitate crystallised out, which was filtered off. Tests on the filtrate with lead acetate in alkaline solution never gave positive results at this stage. All the reagents, filter paper, etc., used in this investigation were of course tested for the presence of cystine.

The two precipitates which were supposed to contain cystine were treated in different manners, till finally the Sullivan reaction — with some modifications described below — was adopted for the determin- ation of cystine.

At the start about fifty precipitates were thoroughly searched under the microscope for cystine. A rather uniform crystalline precipitate was found, very similar in appearance in all the precipitations, in which, in nearly every case (except for the grasses) the typical hexagonal plates of cystine were found embedded. The proportion of cystine to the rest of the precipitate was perhaps only 1 to 200 in most cases, as shown by determinations made on several of the precipitates. In some exceptional cases where larger amounts of cystine were present it was possible to separate it mechanically, the cystine being much the heavier portion. The sulphur content of the cystine was 26'6 per cent., the “crystal sand ” proved to contain none. In cases where it was not possible to separate the cystine, it was determined by an adaptation of a colorimetric method.

It was thought of interest to find out what the precipitate obtained under the above precipitating conditions really consisted of, apart from cystine, so a qualitative analysis was made according to Treadwell and Hall (1924). Silicates were the only anions found, but the following cations were present: Fe, Mg in small quantities and Na and A1 in large quantities. Occasionally other amino acids could be detected under the microscope, to judge from their crystal form leucine, giycocol and tyrosine (?), but as they w'ere present in only very small amounts they were not more closely identified.

Before going on to the discussion of the details of colorimetric methods, another important point must he mentioned. As stated above, only very small quantities of cystine were found under the microscope. Though it was not considered likely to be the case, yet the possibility was feared of the cystine being destroyed during the process, broken down entirely during the extraction. To make quite sure on the point, T gm. of Merck’s G.R. or IToflman La Roche (Basle) cystine was added to the plant powder for digestion, and was invari-

581

CYSTINE AND SULPHUR CONTENT OE BUSHES AND GRASSES.

ably regained at the end of the process, fractions of milligrams only being missing. It was no doubt an expensive way of testing the point, but was worth the assurance gained. As the cystine was recovered, it could be used over again. As a matter of fact the cystine crystals obtained by this process were better than any of the original material used. Very likely the cystine hexagonals break up into crystal sand when stored for some time; cystine crystals obtained by the author kept their form for at least a year.

It was thought of using Folin’s method (1922) to determine the cystine, but it soon appeared that the values obtained were too high and varied according to the amount of total white precipitates (silicate & cystine) and not with the amount of cystine. Something contained in the rough precipitate developed a deep blue colour with Folin’s reagent, thus the blank was much too high to determine small amounts of' cysfine with any accuracy. It seems that Evans had similar difficulties. At any rate, finally Sullivan’s paper was obtained and his method adapted to meet the requirements of a plant analysis. The revised method of Folin and Marenzi came into the hands of the author too late to be tried out.

At first Sullivan’s prescription was followed accurately, the rough precipitate being dissolved in 01 A HC1, so that a lot of the silicate did not dissolve and could be filtered off. Then 2 c.c. of freshly prepared 1 per cent, sodium cyanide in 0 8N sodium hydroxide was added, care was taken to add 2 c.c. of 5N sodium hydroxide before the reducing agent was added — if this were omitted no colour what- ever appeared. Then the 1 c.c. of' 0'5 per cent, fresh aqueous solution of 12 naphtoqui none-4-sodium sulphonate was added, mixed and finally the 5 c.c. of 20 per cent, anhydrous sodium sulphite in 0'5N sodium hydroxide was added, and allowed to stand for 30 minutes and treated exactly as Sullivan prescribes further. After the final volume had been read, comparison was made with the standard of 1 to 3 mgr. cystine treated in exactly the same way, due allowance being made of course for the aliquot of the unknown. The colours could scarcely be matched and accurate readings were impossible. The colour of the unknown tended towards olivegreen-red. The puzzle was that although surely cystine was present in the solution of the unknown, how could the colours be matched ?

The following method was tried out to overcome the difficulty which after all seemed to work very well. Known amounts of cystine dissolved in the hydrolysates of the plants gave exactly the same colour shade as the unknown simply treated with the Sullivan re- agents, only of a different depth. Why not dissolve the standard in a known amount of plant hydrolysate of the unknown and compare it in the colorimeter with the same amount of the unknown alone? If the unknown contained any appreciable amount of cystine, the reading would be possible. A Bausch and Lomb colorimeter was used, and a formula was calculated for the reading.

If a is the standard in mgr, h the setting (mm.) of the standard, c the reading of the unknown (mm.), then x the amount of the unknown in mgr. can be calculated as follows: —

(a — x) b

x = whence x

c

a b

l^b]

(i)

582

M. IIENRICI.

In dissolving the unknown in (J IN HC1, due allowance must be made in formula (1) for the quantities taken in the colorimetric determination. If e.g. there were 40 c.c. solution of the unknown, and 10 c.c. each were taken for standard and unknown, formula a had to be multiplied by 4 or generally speaking formula (2) is obtained, where d means the part of the aliquot to total amount of the unknown

J abd (2)

(c - b)

The readings were checked with different standards, as the amount of the unknown allowed it, and very satisfactory results were obtained. This procedure was therefore finally adopted. In “ nega- tive ’ unknowns only a yellow colour was developed which could not be matched with the standard in the hydrolysates. Amounts under 1 mg'r. in 100 gm. plant material could not be read accurately and are marked as traces in the tables. Generally 10 c.c. of the hydrolysate were taken for each of unknown and standard. For very weak solutions of the unknown, the whole unknown solution was just divided into 2 portions. For very concentrated unknown solutions 1 c.c. was sufficient to develop an intense colour with the reagents. The final volume of the standard and the unknown, after treatment with the reagents, was always equal, generally 30 c.c.

Owing to the lengthy analyses, only a few could be done in duplicate. These few agreed so well in the results, that the deter- minations were not all duplicated.

Method for Sulphur Determination.

As it was thought possible, although not likely, that there was a relationship between cystine and the sulphur content of the plants, a total sulphur determination was done on all the plant samples. The method of Frear (1930) was found exceedingly useful for the purpose. As most Fauresmith plants contain large ^mounts of sulphur, 0 5-2-0 gm. of the ground plant powder were used according to the amount of sulphur expected. The barium sulphate was pre- cipitated hot.' The precipitate was filtered through Jena Glass Filter No. 4. All analyses were done in duplicate.

For the protein determination the usual Kjeldahl method was used.

Results.

Table 1 shows the protein and sulphur content of all the monthly samples in the particular season as well as (he cystine content of (he selected samples. As can be seen at the first glance, none of the three compounds is constant through the season nor are the fluctua- tions for the different species uniform.

The Protein Content.

The protein content, being the best known, may be considered first. There is no doubt that the rainfall has a great influence on the protein content, on the other hand some plants seem to be much more independent of the rain than others.

583

CYSTINE AND SULPHUR CONTENT OF BUSHES AND GRASSES

Table 1. — SULPHUR, PROTEIN, AND CYSTINE CONTENT OF FAURESMITH PLANTS IN THE SEASON, 1929-30.

Date.	Salsola Aphylla.	Salsola Glabrescens.
Sulphur as Per- centage S04 of Dry Matter.	Protein as Per- centage of Dry Matter.	Cystine as Per- centage of Dry Matter.	Sulphur as Per- centage S04 of Dry Matter.	Protein as Per- centage of Dry Matter.	Cystine as Per- centage of Dry Matter.
1929.
Mav	—	—	0-025	1 -88	17-89	0-014
June	—	—	—	—	—	—
July	—	—	—	—	—	—
August	—	—	—	—	—	—
September	400	18-81	0-025	1-94	21-48	0-013
October	4-72	18-99	0-006	3-20	25-46	0-039
November	4-21	26-25	0-010	3-63	22-84	0-008
December	4-86	23-72	0-012	3-15	22-31	—
1930.
January	4-28	21-52	0-001	1-63	22-31	0-002
February	3-63	20-74	0-065	2-24	19-42	0-002
March	3-64	19-95	0-034	2-23	19-42	—
April	3-31	17-31	—	3-30	13-83	—
May	3-52	18-55	0-004	2-00	15 -75	0-018
• 1 une	3-21	19-95	—	2-43	15-23	0-013
July	3-30	19-56	0-036	2-89	14-26	—
August	3-43	'		2-93	13-26	0-009
September	2-70	18-33	0-035	2-45	12-43	0-017
October	3-26	16-31	0-044	3-00	12-86	—
November	—	—	—	2-49	20-39	0-021

Table 1.— SULPHUR, PROTEIN. AND CYSTINE CONTENT OF FAURESMITH PLANTS IN THE SEASON 1929-30— continued.

	Atriplex Capensis.	Atriplex Nummularia.
Date	Sulphur as Per- centage S04 of Dry Matter.	Protein as Per- centage of Dry Matter.	Cystine as Per- centage of Dry Matter.	Sulphur as Per- centage S04 of Dry Matter.	Protein as Per- centage of Dry Matter.	Cystine as Per- centage of Dry Matter.
1929.
May	2-76	21-92	—	—	—	—
June	—	—	—	—	—	—
July	—	—	—	—	—	—
August	—	—	—	—	—	—
September	1 93	26-77	—	2-86	25-59	0-004
( Ictober	1-96	24- 19	0-025	2-64	22-31	—
November	2-42	23-80	0-037	2-26	22-40	0-006
December	1-44	24-06	0-017	2- 14	23-19	0-027
1930.
January	2-23	14-87	0-031	2-50	15-75	0-006
February	2-35	21 ■ 17	—	2-59	21-00	0-009
March	1-24	23-19	0-007	2-44	23-19	—
April	1-24	21-53	—	2-79	20-83	0-021
May	1-64	22-88	0-036	2-95	20-69	0-036
June	1 61	22-58	0-010	2-51	20-21	0-018
July	1-60	18-38	0-034	2-98	18-90	0-016
August	1-87	22-11	—	2-44	18-55	trace
September	1-70	—	0-039	3-08	19-16	—
1 ictober	1-68	26-47	trace	2-94	17-81	0-011

584

M. HENRICI

Table 1.— SULPHUR, PROTEIN, AND CYSTINE CONTENT OF FAURESMITH PLANTS IN THE SEASON 1929-30— continued.

	Tetragonia Arbuscula.	Me.se.in. Hamatum.
Date.	Sulphur as Per- centage SO 4 of Dry Matter.	Protein as Per- centage of Dry Matter.	Cystine as Per- centage of Dry Matter.	Sulphur as Per- centage S04 of Dry Matter.	Protein as Per- centage of Dry Matter.	Cystine as Per- centage of Dry Matter.
1929. May
.lune	1-52	18-40	0-005	—	—	—
July	—	—	—	—	—	—
August	—	—	—	—	—	—
September	1 34	21-44	0-039	0-60	10-6	—
( letober	1 • 17	19-69	0-002	0-76	9-98	—
November	1-30	22 • 92	0-014	0-86	11-46	0-013
December	1 50	23-36	—	0-37	9-62	—
1930. January	110	21-52	0-016	0-40	10-24	0-023
February	107	20-30	0-050	0-32	10-32	0-012
March	1 23	21-09	0-097	0-44	11-99	0-010
April	1-20	20-75	—	0-42	10-50	—
May	1-20	18-99	0-015	0-53	9-01	0-016
June	0-88	16-19	0-008	0-42	9-76	—
July	0-78	12-60	0-018	0-42	8-75	0-003
August	0-86	12-16	0-1852	0-41	9-45	—
September	118	18-86	—	0-39	8-36	0-018
October	1-27	22-75	0-0152	0-43	11-20	0-009

Table 1.— SULPHUR, PROTEIN, AND CYSTINE CONTENT OF FAURESMITH PLANTS IN THE SEASON 1929-30 —continued

	Digitaria Eriantha Stolonifera.	Eragrostis	Curvula Var. Conferta.
	Sulphur	Protein	Cystine	Sulphur	Protein	Cystine
	as Per-	as Per-	as Per-	as Per-	as Per-	as Per-
	centage	centage	centage	centage	centage	centage
	S04 of Dry	of Dry	of Dry	S04 of Dry	of Dry	of Dry
	Matter.	Matter.	Matter.	Matter.	Matter.	Matter.
1929.
May	—	—	—	—	13-12	0-0
June	—	—	—	—	—	—
July	0-39	7-96	—	—	—	—
August	—	—	—	—	—	—
September	0-81	20-48	0-033	—	—	0-0
October	—	14-96	—	0-36	10-59	—
November	0-69	13-91	0-010	0-67	12-51	0-0
December	0-51	13-65	—	0-62	15-75	0-0
1930.
January	0-55	12-60	—	0-50	13-30	0-0
February	0-33	10-15	0-009	0-37	12-69	—
March	0-51	10 06	—	0-38	10-50	—
April	0-55	8-09	—	0 • 40	11-02	—
May	0-46	8-21	0-009	0-35	8-49	0-0
June	0-06	5-43	—	0- 19	5-25	—
July	0-38	5-67	0-006	0-38	4-73	0-0
August	0-38	5-25	—	0-45	4-81	—
September	0-39	16-36	—	0-60	12-95	0-017
October	0-78	13-38	0 • 002	0-58	14-61	0-0

585

CYSTINE AND SULPHUR CONTENT OF HUSHES AND GRASSES.

Table 2. — Rainfall at Fauresmith During the Time of the Investigation in Inches.

	1929.	1930.	1931
January	2-21	2-87	2-82
February	00	1-20	1-18
March	2-74	1 69	2-53
April	0-48	2-34	2-38
May	0-46	0 17	0-0
June	0-62	0-38	0-05
July	0-63	00	0-88
August	117	0-99	0 05
September	3-51	00	00
October	0-42	0-89	1-44
November	0-29	0-52	2-955
December	2-62	2-00	—

From the rainfall table it is obvious that the season July, 1929, to June, 1930, was a good one, there being one spell of drought after heavy rains from the middle of October to the beginning of December. The season July, 1930, to June, 1931, was much less fortunate, as there was insufficient rainfall from September to the end of Decem- ber, the late season, however, was favoured with rain.

From a comparison of the figures for protein with the rainfall it is evident that no correlation exists for the succulent Mesem. hamatum. The two grasses show the usual seasonal variation, high values in spring decreasing continuously towards the late summer where a rapid fall takes place and nearly constant values through the winter. Eragrostis has its highest values after good rains in the early season, a late season’s rain raises its protein content but not very much. In winter for neither Digitaria- nor Eragrostis leaching takes place owing to the lack of rain and heavy dew. Digitaria has its highest protein content in September, 1929, when the highest monthly rainfall occurred. No effect of the second rainy period is visible unless it is just veiled by a less rapid seasonal decrease. The two Atriple.r and Tetragonia always have their highest protein content after heavy rains. The heavy rains in January, 1930, fell after the January samples of the plants had been collected, hence the low values, at the time of heaviest evaporation. Neither Sat sola aphylla nor Salsola glahrescens seem to depend very much on t lie rain, aphylla having its highest value in the drou ght , jeriod, apd glahrescens in 1930 after heavy grazing in the dry November. For both plants but especially for aphylla , it is characteristic that even in winter their protein value is not low. All the four Chenoporl iareae have their lowest value in spring or summer, Tetragonia and the Mesemhrian- thernum in winter like the grasses. It means that the winter does not inhibit growth in the Clienopodiaceae.

The Sulphur Content.

It is quite obvious that the investigated plants differ very much in their sulphur content. The two grasses and the Mesembrian- themum are by far the lowest. Then follows Tetragonia which like the grasses has its lowest value in winter. Atriple.r Capensis which comes next has its lowest sulphur content in March and April. Atriplex nummularia and Salsola . glahrescens have both a much

586

M. HENRICI.

higher sulphur content and show their minimum in sulphur during the rainy season, and their maximum in spring, independent of prevailing rain or not. The second maximum in the rainy April, 1930 for Sal sola glabrescens and for A triple® is characteristic. Sa-lsola aphylla has the highest sulphur content, Ihe highest values during and after the heavy rains in 1929 and the lowest value in the rainless September, 1930. There is no doubt that Salsola aphylla contains a good deal of inorganic, sulphur, whilst in the grasses most of the sulphur is present in organic form. Sa-lsolas on brak soil can store a very high percentage of sulphur, either as calcium (and magnesium) salt or as sodium salt.

Some of the samples for the season 1930/31 were obtained in a different way, in the case of Euryops and Rhodes grass, different strips being cut at monthly, bi-monthly and three-monthly intervals for analysis. This meant that bulk was sacrificed to quality and it was not possible to make as many cystine analyses as with the other plants. As can be seen from Table 3 the protein content of Euryops, a winter flowering plant, is highest in May but after this the plant could not stand the monthly cutting, and only one more figure could lie obtained. Rhodes grass had also its highest protein content in the early winter, later on owing to the heavy frosts it died entirely down. Tripteris pachypteris is at its best in summer, but grows very well in the early winter and flowered a second time in dune. Neither Pentzia incana nor Tripteris have outstanding values in protein, but on the other hand Tripteris never decreases its protein content very much, although Pentzia does so during drought. Pentzia has its best values after the rainy period in January and March.

With regard to the sulphur content, Tripteris is the leader on Fauresmith soil, which is not brak. Values to nearly 6 per cent, are reached in spring, the lowest value falling during and after the heavy January rains. Pentzia does not contain much sulphur and does not vary its sulphur content to any extent. Euryops shows considerably more and varies in rather an irregular way, this may be due to the close cutting. Rhodes grass has for a grass a fairly high sulphur content, of course not high compared to the bushes; its maximum is in winter, the lowest values being found in the rainy season though the difference’s on the whole are not large.

From the foregoing it is evident that protein and sulphur content do not vary uniformly for all the species. Some of them have their lowest sulphur content in the rainy season (Tripteris, Rhodes grass, Atriplex nummularia, A triplex capensis and Salsola glabrescens). The others have it in the winter (Salsola aphylla, Tetragonia, M esem- brianthe mum hamatum , J)i ’-git-aria eriantha slalom fern and E ragrosl is curvula conferta). But most of these plants show a second relative minimum in the other period as well.

With regard to the protein content, three types of plants may be distinguished, (a) a group with a high protein content in early summer decreasing towards autumn: Salsola aphylla and glabrescens, Mesem. hamatum , E ragrosl is conferta and JEgitaria eriantha stoloni- fera. ( b ) The second group which is spread over all the dry parts of South Africa has two distinct maxima of protein content, one early

587

Table

CYSTINE AND SULPHUR CONTENT OF BUSHES AND GRASSES

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in the season and another after the good rains in January. The two Atn plex, Tripteris, Rhodes grass and T etragonia fall in this group, (c) The last group is the typical winter flowering plant Euryops multifidus with a maximum in winter. The maximal value in protein reveal at the same time a maximum in growth of the plant.

Comparison of the Decrease of Sulphur and Protein Content.

From Table 1 it can he seen that for Digitaria the sulphur content decreases in winter to less than 10 per cent, of its high spring value and to about 28 per cent, for Eragrostis, whilst the corres- ponding protein values are 24 per cent, and -11 per cent, respectively of the spring values. For the bushes the relation is quite different, as Table 4 indicates.

Taule 4.

	Lowest Sulphur Content Expressed as Percentage of Highest.	Differ.	Lowest Protein Content Expressed as Percentage of Highest.
Salsola aphylla	62	+ 6	56
Ealsola glabrescens	49	+ 4	45
Atriplex capensis	51	— 5	56
Atriplex nummularia	69	+ 7	62
Tetragonia arbuscula	51	— 1	52
Euryops multifidus	38*		33*
Tripteris pacliypteris	35	-29	64
Pentzia incana	70	+23	47
Mesem. hamatum	27	-43	70
Rhodes grass	56*	- 3	59*

* No winter values available.

With few exceptions the percentage decreases for sulphur and protein are much closer than for grasses, and therefore also much nearer than for Evans (1931 p. 811) samples. One exception is a Mesembrianthernum, of which the metabolism is still a closed book, another is Pen tzia incanci forma which varies but little in its sulphur content but a good bit in its protein content. At first sight it might be thought that on the whole there is a close relationship in the fluctuations of the sulphur and protein contents, as the percentage variations are so small. But it has to he remembered that only in a few cases are the lowest protein values found at the same time as the lowest sulphur values, neither are the maxima found at t lie same time (see especially Euryops and Tripteris ) so that this table loses its convincing aspect and as in Evans’ investigation it has to he concluded that there is no direct relation between sulphur and protein content. Table 5 expresses the sulphur values at the time of the lowest protein value as a percentage of the sulphur value at the time of the highest protein content and proves the aforesaid statement.

It can be seen that for a few plants the sulphur even increases as the protein decreases and in all other cases the protein content falls off to a much larger extent than the sulphur content. The differences are on the whole much larger than Evans’ (1931) differences, only Digitaria and Rhodes grass come near his figures; this fact, however, seems entirely due to the different plants and surroundings.

21

539

CYSTINE AND SULPHUR CONTENT OF HUSHES AND GRASSES.

Table 5.

	Sulphur Value at the Time of Lowest Protein Value Expressed as Percentage of S-value at the Time of Highest Protein Value.	Differ.	Lowest Protein Content Expressed in Percentage of the Highest.
Salsola aphylla	77	21	56
Salsola glabrescens	77	32	45
A triplex capensis	109	53	56
Atriplex nummularia	87	25	62
Tetragonia arbuscula	57	5	52
Euryops multifidus	81*	48	33*
Tripteris pacliypteris	1.54	90	64
Pentzia incana	93	46	47
Mesem. hamntum	89	19	70
Eragrostis conferta	73	49	24
Digitaria eriantha	47	16	31
Rhodes grass	78*	19	59*

* No winter values available.

The Cystine Content.

The cystine content may first he considered quite independently of the protein and sulphur contents, as to its order of size. A first glances at Tables 1 and 3 reveals that on (lie whole the cystine content is very small. A few exceptions will lie discussed later.

If a calculation is made how much of such plants a slice]) must eat to obtain its cystine content in 10 lb. of wool, the following figures are found : —

Weight of wool 10 lb. (German lb.)

Cystine in wool 13'0 per cent. = T3 lb. cystine = 650 gin.

A figure which is often met with in Tables 1 and 3 is 0 02 per cent. Cystine.

Taking this as basis, it would take 3,250,000 grams or 6,500 lb. (of 500 gm.) of dry plant food, to supply the 650 gm. of cystine in 10 lb. of' wool, i.e. to produce a year’s growth. As plants in the veld in South Africa contain about 50 per cent, water, 13,000 lb. of fresh matter per year would be required. The daily ration would amount to 35 6 lb., a figure which is about four times higher than the known daily intake of a sheep. With plants poorer in cystine (e.g. Etacjrostis) the discrepancy would still be greater. From this deduction alone it seems unlikely that the sheep cover their cystine content from the cystine contained in the Karroo plants. It is quite likely that the cystine present in certain plants has a stimulating effect on the growth of wool and hair, as shown in many papers on the physiological effect of cystine (See Abderhalden 1930, p. 580 tf.), but to the author’s mind they do not prove that cystine must necessarily be present in the food of the herbivorous animal. The mistake which is generally made is the assumption that cystine is the

590

M. HENRICI.

only organic sulphui' compound in the plant. Evans (1931) lias pointed out that there must be other organic sulphur compounds present in the plant, from which cystine can he easily prepared by the animal body. In the present investigation, sulphur determina- tions were made on several of the hydrolysates or on the original hydrolysed material after the cystine had been removed. The original plant material, after being hydrolysed with a 20 per cent, hydrochloric acid for 8 hours contained only a small portion of sulphur with the exception of the grasses which contained more than half their sulphur content in this form. All other sulphur is found in the rejected hydrolysates or their wash water, which are still slightly acid after the cystine has been precipitated. The sulphur is mostly in S-H form. The plants do