1950 Onderstepoort Journal of Veterinary Science and Animal Industry, Volume 24, 1950

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Contentes Pages: Onderstepoort Journal of Veterinary Research, Vol ??, 19??

CONTENTS

*Volume 24: Numbers 1 & 2*

Section I: Parasitology

Zoological Survey of the Union of South Africa. Tick survey. Part IV. Distribution of Rhipicephalus capensis, the Cape brown tick	Theiler, G	7

Zoological Survey of the Union of South Africa. Tick survey. Part V. Distribution of Rhipicephalus evertsi, the red tick	Theiler, G	33

Zoological Survey of the Union of South Africa. Tick survey. Part VI. Distribution of the Ixodids : Ixodes pilosus and Ixodes rubicundus	Theiler, G	37


Section II: Toxicology

Recent investigations into the toxicity of known and unknown poisonous plants in the Union of South Africa. XVI	Steyn, DG	53


Section III: Nutrition

The nutritive value of South African feeding stuffs. III. Digestible nutrients and metabolizable energy content of a mixture (1:1) of lucerne hay and yellow maize at different planes of intake for sheep	Truter, GJ & Louw, JG	57

Digestibility of lucerne hay with special reference to experimental technique in digestion trials	Groenewald, JW, Myburgh, SJ, Laurence, GB & Louw, JG	67

The availability of the calcium and phosphorus in " electrofos " for bone formation. I. In the rat	Reinach, N & Louw, JG	87


Section IV: Physiology

Studies on the photosensitisation of animals in South Africa. XII. An attempt to identify the icterogenic factor in geeldikkop; the reaction of nitrous acid on chlorophyll	Sapiro, ML	105

Studies on the alimentary tract of merino sheep in South Africa. XVI. On the identity of Schizosaccharomyces ovis. Part I. Some yeast-like organisms isolated from the rumen contents of sheep fed on a lucerne diet	Oxford, AE, Quin, JI & Van der Westhuizen, GCA	119


Section V: Reproduction

The influence of delayed breeding on the fertility of beef heifers	De Lange, M	125


Section VI: Wool Research

Studies on wool grease and suint. I. The refractive index of wool grease	Rossouw, SD	355

Author index		363

Subject index		364

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Now showing 1 - 13 of 13

Subject index
(Published by The Government Printer, Pretoria, 1950) Anonymous; De Kock, G.v.d.W.
Author index
(Published by The Government Printer, Pretoria, 1950) Anonymous; De Kock, G.v.d.W.
Studies on wool grease and suint. I. The refractive index of wool grease
(Published by The Government Printer, Pretoria, 1950) Rossouw, S.D.; De Kock, G.v.d.W.
1. The refractive index of 23 samples of wool grease from different sources of raw wool has been determined over a temperature range from 25° C. to 50°C. 2. Curves plotted from the data show a definite form of considerable similarity. 3. It is recommended that 50°C. should be adopted as the temperature at which the refractive index of wool grease should be determined. 4. Compared with other fats and oils the refractive index of wool grease varies considerably. The average value obtained is 1•4752 at 50° C. 5. From the shape of the curves the refractive index at temperatures outside the melting range can be calculated with a fair degree of accuracy.
The influence of delayed breeding on the fertility of beef heifers
(Published by The Government Printer, Pretoria, 1950) De Lange, M.; De Kock, G.v.d.W.
(1) Twenty-five beef heifers were subjected to delayed breeding up to ages varying from four years to five years eight months. (2) Observations on body-weights, age of sexual maturity, the periodicity and duration of oestrus and the results of mating are recorded. (3) Seven heifers bred successfully, while the remainder showed extensive disturbances in sexual activity. (4) The changes occurring in the genital tract during the normal sexual cycle and during pregnancy are described. (5) Profound functional and structural changes were observed in the genitalia of the majority of animals, leading to abortion, functional sterility, nymphomania and anaphrodisia. (6) Correlative macroscopical and histological changes were observed in the anterior pituitary, thyroid and adrenals of normal and affected animals. (7) The genesis of sterility in relation to delayed breeding in the light of the structural and physiological alterations observed, is discussed.
Studies on the alimentary tract of merino sheep in South Africa. XVI. On the identity of Schizosaccharomyces ovis. Part I. Some yeast-like organisms isolated from the rumen contents of sheep fed on a lucerne diet
(Published by The Government Printer, Pretoria, 1950) Oxford, A.E.; Quin, J.I.; Van der Westhuizen, G.C.A.; De Kock, G.v.d.W.
All attempts by the usual mycological techniques to isolate 'Schizosaccharomyces ovis', have failed although other yeast-like organisms have been isolated, often in quantity, from rumen ingesta. None of these organisms have the characteristic properties of 'Schizosaccharomyces ovis' as present in sheep's rumen ingesta, viz. the power of quick fermentation of added glucose with simultaneous storage of massive amounts of glycogen in the cells. The rumen 'yeasts' have also been shown not to be Mucor spores or oidia or yeast like forms of Monilia which they resemble in size and shape. From this and other evidence, it is concluded that 'Schizosaccharomyces ovis' is misnamed and is probably not a member of the Eumycetes at all.
Studies on the photosensitisation of animals in South Africa. XII. An attempt to identify the icterogenic factor in geeldikkop; the reaction of nitrous acid on chlorophyll
(Published by The Government Printer, Pretoria, 1950) Sapiro, M.L.; De Kock, G.v.d.W.
1. The reaction of nitrous acid on chlorophyll yielded four compounds, denoted for convenience as A, B, C and D. 2. The compounds are all distinctive in appearance, are highly coloured and three of them have sharp melting points. 3. A convenient process of separation of the compounds and easy methods for the purification of A, B and C have been found. 4. A, B, and C all appear to be tetra-substituted pyrrole derivatives. A and B each exhibit tautomerism, probably of the nitroso-isonitroso type, whereas C appears to have only one form. 5. A and B form mono-acetyl derivatives, but C yields no derivatives of this type. 6. Formulae have been tentatively proposed as follows: A (Molecular formula): C₁₄ H₁₃ N₃ O₃ B (Molecular formula): C₁₄ H₁₆ N₂ O. C (Empirical formula): C₁₃ H₁₀ N O or C₁₃ H₁₁ N O. 7. None of the compounds exhibited icterogenic or photosensitising properties when administered to sheep, either by subcutaneous injection or by oral administration.
Digestibility of lucerne hay with special reference to experimental technique in digestion trials
(Published by The Government Printer, Pretoria, 1950) Groenewald, J.W.; Myburgh, S.J.; Laurence, G.B.; Louw, J.G.; De Kock, G.v.d.W.
Five steers were used to determine the digestion coefficients of the Dry Matter, Crude Protein, and Crude Fibre of lucerne hay during five separate periods. The analysis of the resultant data shows that period has no influence on the coefficients of Crude Protein, but there is some evidence of a period influence on the coefficients of digestion of Dry Matter and Crude Fibre. In consequence it is concluded that the Latin Square or Randomized Block Technique of Fisher should be adhered to wherever possible, but since period effects tend to be very small, an alternative technique is suggested in the interests of simplicity.
The availability of the calcium and phosphorus in " electrofos " for bone formation. I. In the rat
(Published by The Government Printer, Pretoria, 1950) Reinach, Norman; Louw, J.G.; De Kock, G.v.d.W.
A basal diet, containing 0•06 per cent. calcium and 0•05 per cent. phosphorus, and albino rats, 4 to 5 weeks old and weighing approximately 60 grams, were used to ascertain the availability of electrofos I and electrofos II in comparison with dicalcium phosphate for bone formation. These phosphatic products, prepared by a thermal process, were studied at two levels giving diets containing 0•18 per cent. phosphorus and 0•36 per cent. phosphorus, the Ca : P ratio being maintained at about 2 : 1. Apart from live weight gains percentage retention of the relevant minerals as determined by slaughter tests and femur ash were used as criteria for evaluating the products. The averages of the results obtained are summarized in Table 18. It was found that both electrofos I and electrofos II were significantly less available for bone formation than calcium phosphate. However, more or less equal bone formation was obtained when these products were supplemented at about twice the level of calcium phosphate.
The nutritive value of South African feeding stuffs. III. Digestible nutrients and metabolizable energy content of a mixture (1:1) of lucerne hay and yellow maize at different planes of intake for sheep
(Published by The Government Printer, Pretoria, 1950) Truter, G.J.; Louw, J.G.; De Kock, G.v.d.W.
Mature Merino sheep were used as experimental subjects in a study of the digestibility of a ration of equal parts by weight of lucerne hay and crushed maize at three levels of nutrition, viz. maintenance, 1 ½ x maintenance and 2 x maintenance. The data yielded the following conclusions: (1) The digestibility of the dry matter was significantly decreased by 2•4 absolute per cent. when the maintenance ration was increased by 50 per cent. Doubling the maintenance allowance had no further influence in this respect. (2) The apparent digestibility of the protein decreased progressively as the plane of nutrition was increased, the decrease over the whole range being 5•2 absolute per cent. This difference was statistically highly significant. (3) The cellulose fraction behaved somewhat like the dry matter whilst "other carbohydrates" (sugars, starch, and hemicelluloses) showed, with increase in plane of nutrition, a progressive decrease in digestibility amounting to 2•9 absolute per cent. at the highest level of intake. This decrease was highly significant statistically. (4) The digestibility of the lignin fluctuated from 4•6 per cent. at the 1 ½ x maintenance level to 13•4 per cent. at the 2 x maintenance level.
Recent investigations into the toxicity of known and unknown poisonous plants in the Union of South Africa. XVI
(Published by The Government Printer, Pretoria, 1950) Steyn, D.G.; De Kock, G.v.d.W.
Drenching experiments with eight suspected poisonous plants and one specimen of fungus-infected mealie meal were conducted upon rabbits and sheep. The only positive result achieved was with Agave Americana and, even in this case, it cannot be stated definitely that the paralysis developed by the rabbit was caused by this plant, as conclusions drawn from an experiment conducted on a single animal may not be reliable.
Zoological Survey of the Union of South Africa. Tick survey. Part VI. Distribution of the Ixodids : Ixodes pilosus and Ixodes rubicundus
(Published by The Government Printer, Pretoria, 1950) Theiler, Gertrud; De Kock, G.v.d.W.
Ixodes pilosus: 1. The distribution of I. pilosus has been given in terms of political divisions, as well as in terms of vegetational coverage. 2. It appears to be associated with sour-veld; sour veld which, in its turn, is mainly associated with high rainfall in most instances. 3. From the data available it is difficult to establish which factors influence its activities or which factors exercise a limiting role to its distribution. It is liable to be present during most seasons in most areas. 4. The data available suggest that it can be controlled with the usual arsenical dips. Ixodes rubicundus: 1. The distribution of Ixodes rubicundus has been given in terms of political divisions, as well as in terms of vegetational coverage. 2. I. rubicundus is shown to be confined to the moister regions of the Karrooveld; regions which are more generally hilly or mountainous rather than fiat and open. 3. I. rubicundus is shown to be active in the early winter months of April and May; occasionally it is active until July. Its occurrence during summer months is very exceptional. 4. As it occurs in areas where dipping is not practised, it is impossible to conclude from the data presented in the survey, what effect dipping has on it. 5. I. rubicundus is the only tick incriminated thus far with tick paralysis in South Africa.
Zoological Survey of the Union of South Africa. Tick survey. Part V. Distribution of Rhipicephalus evertsi, the red tick
(Published by The Government Printer, Pretoria, 1950) Theiler, Gertrud; De Kock, G.v.d.W.
1. The distribution of R. evertsi is given in terms of political Divisions, as well as in terms of Vegetational coverage. 2. R. evertsi is seen to be present in all forest, parkland and grass land areas with a rainfall above 10 inches. It is absent from all Karroo areas below 10 inches; it appears to maintain a precarious footing in mixed Karroo scrub and grass areas with a rainfall between 10-15 inches. 3. It shows no essential periodicity in its activities. 4. It is not controlled by dipping alone; handdressing with dipping is essential for its suppression.
Zoological Survey of the Union of South Africa. Tick survey. Part IV. Distribution of Rhipicephalus capensis, the Cape brown tick
(Published by The Government Printer, Pretoria, 1950) Theiler, Gertrud; De Kock, G.v.d.W.
(l) The distribution of R. capensis has been given in terms of political Divisions, as well as in terms of vegetational coverage. (2) R . capensis shows a tendency to become inactive during the April-June period, independently of whether this is the coldest, the wettest or the driest time of the year. From the data available. it is impossible to establish a behaviour pattern for this species. (3) The factors limiting the distribution of R. capensis are difficult to establish. Extreme heat and extreme cold do not affect it. Humidity, in terms of precipitation, alone, does not play an important role- but it would seem that humidity associated with plant coverages does influence the distribution. In scrub country i.e., Karrooveld it would appear that R. capensis can support much greater aridity than it can in grass veld. It is seldom, if ever, present in the open veld of short- or mixed-grasslands; in the tall grass lands it occurs only, apparently, in the moister areas. In these eastern tall grass lands the disturbances in the distribution picture may be ascribed to the dipping practices.

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