1. The longissimus dorsi muscles of cattle have been analysed for moisture, intramuscular fat (and its iodine number), nitrogen (total, myofibrillar, sarcoplasmic, soluble non-protein and stroma), myoglobin, total soluble phosphorus and ash; ultimate pH and buffering power were also determined.

2. At birth, in the region of the 4th, 5th and 6th lumbar vertebrae, total, myofibrillar, sarcoplasmic and soluble non-protein nitrogens have attained 87, 76, 71 and 25% of their mean adult values, respectively; the concentration of stroma nitrogen diminishes by 50%, between birth and maturity.

3. The mean adult values (fat-free basis) for sarcoplasmic (0·9%) and myofibrillar (1·9%) protein nitrogen, for total nitrogen (3·6%) and for moisture (76·8%) are atained at approximately 5 months, 7–10 months and 18 months of age, respectively; moisture on a whole tissue basis decreases fairly regularly as intramuscular fat increases.

Although considerable work has been done on basal metabolism and maintenance requirements of animals, maintenance needs in relation to total feed requirements for production have not received much attention in South Africa. Most workers have investigated production requirements, whilst the part of the total needs of the fattening of steers used for maintenance, has received very little attention.

This capital cost or ‘overhead’ expense is an item which constitutes a large proportion of the animals' fattening ration. In South Africa, only a small percentage of cattle is marketed under 4 or 5 years old. The maintenance cost of these animals must be considerable and the nett efficiency of beef production very low. As only the amount of a ration in excess of the maintenance requirements can be utilized for production, it follows that a level of nutrition well above the requirements for maintenance will facilitate a more efficient production system by narrowing the ratio between the part of the ration used for maintenance and that used for production. It is well known that differences in the efficiency of production between steers can only be due to the difference in the level of feed intake above maintenance needs—hence probably the strong correlation between rate of gain and efficiency of feed utilization. Apart from the actual determination of maintenance needs the object of this investigation was to determine the relationship between maintenance requirements and the total feed intake of beef steers when fed on fattening rations containing different ratios of concentrates to roughage.

A method of combining dried faeces in order to reduce analyses of samples was investigated.

The effect of the length of digestibility trials and the number of animals required in relation to accuracy have been investigated and discussed.

As a result of our investigations the following procedure was adopted.

1. An experiment was conducted to study the effects of progesterone and pregnant mare serum (p.m.s.) on incidence of oestrus, macroscopic changes in the ovaries, histological appearance of the genital tract, the vaginal smear and cervical mucus of New Zealand Romney Marsh ewes in deep anoestrus. Ten animals served as controls, thirty-five received progesterone daily for 4–12 days and ten were given p.m.s. alone. The remaining fifteen ewes were treated with progesterone for 4–6 days followed by p.m.s.

2. In ewes treated with progesterone alone, neither ovulation nor oestrus resulted. After p.m.s. alone six animals ovulated, while injection with both hormones caused ovulation in all 15 ewes and one was in oestrus.

3. Sections cut from the mid-region of the fallopian tube, uterine horn and cervix were examined. Histological responses to progesterone and p.m.s. were found in all positions of the tract and were greatest in the ewes which had ovulated.

4. In the ewes which ovulated a sequence of macroscopic and microscopic changes occurred in the vagina and these seemed similar to those associated with ovulation during the oestrous cycle.

5. Crystallization patterns in cervical mucus were seen in some ewes of all groups. Accompanying ovulation the phenomenon was seen for several days but was absent during most of the luteal period. When no follicles ruptured cervical mucus patterns often persisted. In most cases the presence and absence of arborization was presumably related to follicular oestrogen and progesterone from an induced corpus luteum and was in similar time relationship to that normally accompanying ovulation in the oestrous cycle. Some inconsistency in the response of cervical mucus following hormone treatment was noted.

6. No evidence was found that hormone treatment had initiated a regular cycle of ovarian activity.

It is shown that the available energy, T.d.n. or S.e., contained in the dry matter of Kenya pastures at all stages of growth is remarkably constant. Thus in the early stages of growth of such pastures when the available D.c.p. is present in amounts suitable for very high milk yields the available energy limits their attainment. During later growth, as the amount of C.p. in the pasture becomes increasingly diluted by carbohydrate there is a progressive decrease in amount of available D.c.p. and it in turn becomes inadequate to sustain the original limited level of productivity.

The intake of dry matter from a pasture of Pangola grass by lactating dairy cows was measured. The chromic oxide administration technique was used. It was shown that the intake of dry matter was significantly higher in the dry season than in the wet. Reasons for this were discussed. An assessment of the nutrient intake of the animals was made and it was concluded that if the requirements of cattle in temperate climates was taken as a guide, this was adequate for at least maintenance and production of 1½ gal. per day of milk in the wet season. Under dry season conditions the intake of total digestible nutrients was adequate for the same level of production, but the digestible protein level was considerably below requirement. It was therefore concluded that supplementation with protein concentrates in the wet season was unnecessary save for high-yielding cows, but that all cows required concentrates during the dry season conditions of the experiment.

1. Unmuzzled milk-fed calves which ate considerable amounts of wood shavings after they were a few weeks old showed a much bigger increase with age in volume of rumen fluid and in flow rate of fluid out of the reticulo rumen than did muzzled milk-fed calves. It is suggested that these differences were due mainly to increased saliva production in the calves eating shavings.

2. Milk leaked into the rumen at feeding in eight out of twenty-four experiments. There was no indication that shavings ingestion increased the incidence of leakage nor that age up to 16 weeks had any marked effect. The leakage appeared to be a consistent characteristic of certain calves rather than a random occurrence and did not appear to affect adversely growth or health.

1. An investigation concerning the weights twenty-four beef steers (three breeds—Hereford, Dairy Shorthorn and Friesians—on four planes nutrition), their grades, weights of organs, carcasses, tissues, etc., together with the chemical composition of their muscular and fatty tissues has been carried out.

2. The resultant data have been used to calculate—mainly by an analysis of variance—the effect of breed and level of nutrition. Only statistically significant differences are dealt with in this summary.

1. Individual herbage species were grown in pots and their magnesium contents studied throughout the growing season. The effects of treatments with sulphate of ammonia, superphosphate and calcined magnesite were also investigated.

2. Of the grasses studied timothy was consistently the lowest in magnesium content, the rye-grasses and cocksfoot being appreciably higher and similar. The clover species had higher magnesium contents than the grasses, especially in the spring.

3. The magnesium contents of the grass species were lowest in spring and showed a marked increase as the season advanced. The corresponding increases in clover magnesium content were considerably smaller.

4. The effects of sulphate of ammonia and superphosphate were slight increases in magnesium contents, but the calcined magnesite resulted in major increases in magnesium contents of both grasses and clovers.

1. Seventeen experiments in 1957–59 on the Lincolnshire Limestone soils tested the response of sugar beet to 2·5 cwt. potassium chloride per acre (as commercial muriate of potash, 60% K2O) and its chemical equivalent in sodium chloride: 1·8 cwt. per acre. Average response of sugar yield to sodium was higher than to potassium, especially in the wet summer of 1958. There was a negative interaction between sodium and potassium; in the presence of sodium it was uneconomic to apply potassium.

An objective, general classification of animal feedingstuffs in terms of their efficiency of use by pigs or ruminants can be made on the basis of earlier analyses of the relationships between the percentage crude protein and crude fibre contents of the dry matter of feeds and the differing digestibilities of c.p. and total nutrients by both classes of animal. It is shown to be in good agreement with the present empirical classification which is based on practical experience.

In an earlier paper the estimation of the total digestible nutrients (T.d.n.) to be expected in ruminant feedingstuffs has been described (Glover, J. Duthie, D. W. & Dougall, H. W. 1960). In a like manner the average T.d.n. in pig feeds can be estimated. The necessary equations have been obtained in earlier papers (Glover & Duthie, 1958A, b). They are, respectively

where C.p. and C.f. are percentage crude protein and crude fibre, respectively, in the dry matter of the feed, D.c.p. is digestible crude protein and N.r. the nutritive ratio. They can be used directly for the estimation of T.d.n. because by definition T.d.n. is D.c.p.(N.r. + 1); thus the T.d.n. to be expected at different levels of C.p. and C.f. can readily be calculated. Table 1 shows in abbreviated form some of the values that are obtained in the ranges 0–30% C.p. and 0–40% C.f., while Fig. 1 illustrates in detail the effect on T.d.n. of changing C.p. and C.f. levels of the diet. This figure shows clearly the very marked effect of increasing C.f. depressing the digestibility of the total nutrients in pig feeds, a fact which is already well known.

Seedling beet plants grown on a fine soil separate produced more and larger leaves than those grown on coarser separates. This result has been ascribed to the greater quantity of available water, and the better root-soil water contact, in the fine separate compared with the others. Difficulties of root establishment in the coarser separates may retard the start of leaf development relative to that in the fine separates. Soil separates also affected leaf number, in some experiments, through their effect on seedling emergence, in that rapid emergence gave seedlings a slightly longer period for leaf production.

Fodder beet plants (variety Red Otofte) had a greater leaf number per plant at all counts than plants of any of the sugar-beet strains grown. Polyploid sugar-beet seedlings had larger leaves than diploid seedling.

Nitrogen applications to the seed-bed did not stimulate leaf production. In one instance, heavy fertilizerdressingsretardedleafproduction,probably by an osmotic effect.

1. Two experiments designed to investigate the effects of different times of ploughing a clover ley on the growth and yield of the subsequent winter wheat crop are described and the results discussed.

2. Although the different times of ploughing led to considerable differences in the growth of the wheat, their effect on yield was not consistent. This in agreement with the results of an earlier series of experiments. The effects of time of ploughing are attributed mainly to the resulting differences in the physical condition of the seed-beds.

1. Twenty-nine experiments on sugar beet in 1957–59 compared ploughing-down of phosphate and potash in the previous autumn with spring application before the seed-bed preparations.

2. On average, spring application gave a higher yield of sugar and tops than ploughing-down, both in the wet summers of 1957 and 1958 and in the dry summer of 1959.