1. The effect of fattening, age and the ratio of concentrates to roughage in a ration on the development of beef steers was investigated. The specific purpose was to study developmental patterns during the short-term fattening of beef steers of different ages in order to ascertain to what extent beef steers improved in the proportions of the various body parts, offals, organs and tissues.

2. The experimental material consisted of 104 beef steers of three age-groups, namely, ± 8, ± 20 and ± 32 months old, fed on rations differing in the ratio of concentrates to roughage and 36 control steers of the same age-groups, slaughtered at the start of the experiment.

3. When the weights of the parts of the carcasses were expressed as a percentage of the carcass weight, it was found that with the exception of a few parts, the percentage which the parts constituted of the carcass remained remarkably constant in the various groups. The effect of age in both the fattened and unfattened groups was comparatively small, whilst the effect of fattening was of slightly greater magnitude. The effect of the ration concentration per se was negligible.

4. The parts where fat was deposited formed a significantly (P < 0·01) larger percentage of the carcass of the fattened than of the unfattened steers (kidney and channel fat, thin flank and cod, brisket, plate and neck).

5. The shoulder, chuck and buttock and rump, formed a significantly (P < 0·01) lower percentage of the carcasses of the fattened than of the unfattened steers.

A simple method for the estimation of the digestible non-nitrogenous fraction of normal pig feeds is described. It requires only knowledge of the digestibility coefficient of the crude protein contained in the dry matter of the feed.

More accurate estimates can be obtained by applying to this method a simple correction involving only the crude protein content of the dried feed. Attention is drawn to the intimacy of the relationship between the digestibilities of the non-nitrogenous and nitrogenous components of the diet.

Five perennial fodder crops and maize were grown for 11 years or more in unfertilized soil. The effect of rainfall, annual and seasonal, and age from planting was examined in detail. Increased rainfall, whether annual or seasonal, led to increased yields of all crops, although the extent of the increase depended on the type of crop, the nature of the rainy season, whether long or short, and in particular the age of the perennial crops. All the perennials aged at similar rates and ageing led to reduced yields. The depressing effect of age is thought to be due to overcrowding and possibly a concealed loss of fertility.

The relationship between the exchangeable potassium content of a soil and the activity ratio, aK/√(aCa+Mg), of the solution with which it is in ‘instantaneous equilibrium’ is a characteristic of the soil which is independent of the soil: solution ratio or the total electrolyte concentration (up to O·06 M) of the solution. It is unaffected by the transfer of substantial amounts of potassium ions to or from the fixed state. Hence instantaneous equilibrium curves provide a basis against which to measure the changes in exchangeable potassium content due to fixation and release. This procedure has the important advantages that all measurements are made in the solution phase and that the solutions in contact with the soil approximate to the natural soil solution.

The technique has been employed successfully in studying the fixation and release of potassium by several widely different soils.

The results confirm that fixation or release are determined by the extent to which the soil contains more or less exchangeable potassium than its equilibrium percentage potassium saturation. Seemingly the equilibrium percentage potassium saturation, and hence the equilibrium activity ratio of potassium in the soil solution aK/√(aCa+Mg), is regulated by the amounts or proportions of potassium in the fixed state. The amounts or proportions of potassium in the fixed state may be increased by repeated applications of potassium fertilizers and reduced by continued cropping.

1. Eighty-six bull calves (fifty-two Friesian, twenty-two Ayrshire, twelve Shorthorn) were examined at intervals, during the first year of life, by a method which allowed classification of the degree of adherence between penis and sheath into five classes.

2. Mean age and weight at which separation between penis and sheath commenced and was completed are recorded for each breed. Significant breed differences were found.

3. The rate of separation accelerates as development proceeds.

4. The relationships between age, body weight, and commencement and completion of separation in the Friesian bulls are analysed by correlation methods. These analyses suggest that both age and body weight are important in sexual development.

5. An equation is given for the linear regression of age at completion of separation on age and weight at commencement of separation and weight at 10 weeks for the Friesian bulls.

1. 247 commercial beef calves were examined at ages ranging from 0–13 months.

2. Separation between penis and sheath commenced at about 3 or 4 months and was completed at about 9 or 10 months. Great differences were, however, found between animals of similar ages.

3. The degree of adherence present at castration was greater than that found in a previous survey at the time of slaughter. Evidence is presented to support the suggestion that separation between penis and sheath may take place after castration.

1. The inter-relationships of starch and proteins during fermentation in the rumen are measured by estimating volatile fatty acids, ammonia, lactic acid and amino acids after administering the starch and protein supplements alone or together.

2. The presence of casein stimulates the formation of volatile fatty acids from starch. Simpler nitrogen-containing compounds are less effective than casein; other proteins are as effective as casein provided they are fermented as rapidly in the rumen.

3. Proteins can be divided roughly into three groups on the basis of the rapidity with which they give rise to ammonia in the rumen: casein, gelatin, ground nut protein > soy protein, wheat gluten > bovine albumin, zein.

4. The proportion of acetic acid falls and of propionic acid and higher acids rises as proteins that are rapidly fermented are placed in the rumen.

1. Studies of tissues distribution in beef carcasses of East African ‘Boran’ cattle revealed very high correlations between the separable tissue analysis of the full tenth rib sample joint and of the full side.

2. A comparative study of tenth rib sample joints, from twelve steers and five cows cut at various positions along the length of the rib showed that the full rib sample gave a higher correlation (r = 0·948), with the full side in respect of all tissues except the subcutaneous fat, than any other sample joint. The subcutaneous fat of the whole side could not be predicted with reliability by the use of any rib sample, the highest correlation (r = 0·558) existing between the half-rib sample and the full side.

3. From detailed carcass studies of thirty-two steers and eight cows, including the twelve steers and five cows mentioned above, prediction equations are presented for estimating the percentages of lean, total fat, and butchers' bone in whole carcasses from single complete tenth rib samples. Standard deviations being 1·53% for lean, 1·34% for total fat in steers, 1·13% for total fat in cows and 0·88% for butchers' bone.

4. Where X1, X2 and X3 are respectively the percentages of lean, total fat and bone in the sample joint the prediction equations recommended are as follows:

For the prediction of lean

(i) In carcasses of either sex.

(f) Percentage of lean in the carcass = 0·431X1 + 0·475X3 + 33·58 (subject to a standard deviation of 1·53%).

For the prediction of total fat

(i) In steer carcasses.

(d) Percentage total fat in carcass = 0·664X2 − 0·78 (subject to a standard deviation of 1·34%).

(ii) In cow carcasses.

(e) Percentage of total fat in carcass = 0·641X2 + 0·23 (subject to a standard deviation of 1·13%).

For the prediction of bone

(i) 100 −(equation (f) +equation (d) or (e)).

5. A practical test of the equations referred to in the text is given in Table 4.

Nitrogen applied at ear emergence to winter wheat or spring barley grown in pots with various levels of basal nitrogen fertilizer, increased grain and total dry weight much less than similar amounts of nitrogen applied in March or April. No nitrogen was absorbed after ear emergence from unfertilized soil, or from the early application, and at maturity equal amounts of nitrogen had been absorbed from early and late applications.

Early nitrogen increased final ear number by increasing the number at emergence and also increased grain size. Late nitrogen had negligible effect on yield of ears present when it was applied and caused the production of new shoots with small ears. Nitrogen applied at both times increased leaf area duration after ear emergence similarly; early nitrogen by increasing area at ear emergence and late nitrogen by delaying senescence of existing shoots and causing production of new shoots. The efficiency in grain production of the leaf area present after ear emergence was less with late than with early nitrogen, mainly because of the low efficiency of the shoots produced after ear emergence.

These results differed from those of field experiments in which early and late nitrogen usually increased grain yield similarly, probably because in the field there were no late unproductive tillers and all the late nitrogen was utilized in increasing grain yield of existing shoots. Another difference was that nitrogen uptake from soil in the field continued until maturity.

1. Longissimus dorsi muscles from twenty Landrace and twenty Large White pigs of accurately known history, which had been reared under identical conditions at a Progeny Testing Station, and killed at similar weights, were sampled for ultimate pH and colour at the levels of the 5th, 7th, 9th, 11th, 13th and 15th thoracic, and of the 1st, 3rd, 5th and 6th lumbar, vertebrae.

2. The mean ultimate pH at all ten locations in Landrace muscles was invariably lower than at corresponding locations in Large White muscles, the difference being minimal at the level of the 15th thoracic vertebra, but being highly significant overall.

3. The scatter of ultimate pH values was markedly different between the breeds at the levels of the 5th and 9th thoracic, and of the 1st and 6th lumbar, vertebrae.

4. The mean colour at all locations, except 1st and 5th lumbar vertebrae, was higher in Large White muscles than at corresponding locations in Landrace muscles: the difference was especially marked at the level of the 5th thoracic vertebra.

5. Only in longissimus dorsi muscles from Landrace pigs were there significant correlations between ultimate pH and colour.

1. Information, obtained in the metabolism experiments described previously (Rook et al. 1958; Rook & Balch, 1958), is given on the intake and oxcretion, of calcium, phosphorus, sodium, potassium, water and dry matter by milking cows receiving winter-stall diets or cut-grass in the stall.

2. Grass diets cut from swards at an early stage of growth gave a lower intake of calcium, a lower Ca:P ratio and a lower intake of alkaline earth alkali (Ca + Mg – P in g. equiv./day) than did typical winter diets or a grass diet cut from a sward at a mature stage of growth.

3. The intake of potassium was considerably higher with the grass diets (mean value, 327 g./day) than with the typical winter diets (mean value, 181 g./day). The intake of sodium, however, showed a similar range for cut-grass and winter stall diets, but the lowest average intake, of about 10 g./day, was with an early cut of a cocksfoot/rye-grass sward.

4. The water ingested with the food was highest with the cut-grass diets but this was largely compensated for by a decrease in the water drunk. In a few individual animals, however, diuresis developed a few days after the feeding of grass was commenced and this was associated with a marked increase in the water drunk.

5. No major difference in the metabolism of sodium, potassium or water was observed between the cut grass diets and the winter diets and the results obtained do not support the view that the fluidity of faeces of cattle at pasture in the spring is indicative of diarrhoea and is associated with an excessive loss of nutrients via athe faecal route.

6. There was no evidence to suggest that the development of hypomagnesaemia was related to the amounts of calcium, phosphorus, sodium and potassium consumed and excreted with the cut grass diets.

1. Measurements of the temperatures of the extremities, rectal temperatures, respiratory rates and heart rates have been made in calves during exposure at environmental temperatures within the range – 5·0° –45·0° C.

2. Large variations in the skin temperatures of the extremities were recorded between environmental temperatures of –5·0° and 25·0° C. At environmental temperatures above 25·0° C. the extremity temperatures and the skin temperatures of the trunk were similar.

3. Feeding and localized infra-red irradiation of part of the trunk of the animals resulted in marked increases in the skin temperatures of the unheated extremities.

4. Evidence was obtained that the variations in the skin temperatures of the extremities were brought about by changes of blood flow to these parts.

5. Respiratory rates varied also with the environmental temperature at which the animals were exposed. When the animals were exposed to localized infra-red irradiation of the trunk the increase in respiratory rate was significantly greater when the extremities were initially warm than when they were cool.

6. In addition to spontaneous fluctuations in the skin temperatures of the ears at environmental temperatures of 10·0°–25·0° C, periodic increases in the skin temperatures of the ears were observed in all the calves at an environmental temperature of – 5·0° C. The increase in the skin temperatures of the ears persisted throughout the 7 hr. exposure to an environmental temperature of – 5·0° C.

7. It was concluded that, in a temperate climate, variations in the skin temperatures of the extremities of the ox have a thermoregulatory function.

The effect of using a cover crop of spring oats under three managements and two levels of Nitro- Chalk in the seeding year on Italian rye-grass and broad red clover in the first harvest year were investigated and the following results obtained.

1. Undersowing increased the total yield of dry matter in the Italian rye-grass/broad red clover mixture in the first harvest year. Using a cover crop with the April sowing only increased the yield of herbage when frequent grazing was practised in the seeding year. The percentage of broad red clover and the yield and percentage of crude protein in the clover were higher in spring when a cover crop was used. In the hay cut the percentages of clover and of protein were higher in the Italian rye-grass/broad red clover mixture sown without a cover crop and the yield of crude protein was not affected by undersowing.

2. Early sowing in April resulted in a higher total yield of dry matter and Italian rye-grass in the first harvest year. The growth of broad red clover and the yield of crude protein were also increased in the spring grazing but not in the hay cut. The August sowing resulted in higher winter casualties of the Italian rye-grass and broad red clover, but gave a greater density of plants in the following spring than the swards sown in April.

1. The effects of feeding 6 or 9 oz. of milk substitute in 2 or 3 pints of water per feed were studied in Ayrshire calves weaned at 5 weeks, and of feeding 6 or 9 oz. in 3 pints with calves weaned at 3 weeks.

2. In both experiments higher milk substitute intakes significantly improved growth rate without detriment to the consumption of dry food.

3. Restriction of water to 2 pints per feed tended to reduce live-weight gain and concentrate consumption and increased free water intake, although not sufficiently to compensate for the restriction.

4. In calves weaned at 3 weeks the higher amount of milk substitute produced an effect which was still present at 88 days and this indicated that underfeeding in very early life may be permanently detrimental.

5. Regressions of live-weight gain upon concentrate and free water consumption and the progressive increase in live-weight gain and concentrate intake before weaning indicate the importance of this intake in providing energy for the calf before weaning and the beneficial effects of individual vigour.

6. The marked effects of the various systems of use of similar foods upon the distribution of liveweight gain during the first month and upon cost are described and discussed.

1. A balanced factorial experiment was carried out with forty-eight Merino ewes. There were two levels each of the four factors: environmental temperature, thyroxine status, vitamin A intake and progesterone status. Each ewe was killed at 25 days' pregnancy; its uterus was weighed and portions were prepared for histological examination. A number of morphological indices were then measured.

2. With respect to uterus weight there were significant interactions between thyroxine level, environmental temperature and progesterone level, and between thyroxine level and vitamin A intake. In the absence of thyroxine injections, heat and supplementary vitamin A increased mean uterus weight; in the absence of either of these, thyroxine injections increased it. Heat or vitamin A with thyroxine injections maintained normal mean weight. Progesterone influenced the temperature effect only in the presence of thyroxine.

3. Where thyroxine injections were given at normal temperatures uterus weight was significantly correlated with plasma vitamin A concentration. There was a similar correlation where thyroxine injections were given in the absence of dietary vitamin A.

4. There were no significant treatment effects or interactions on any of the histological indices examined. The height of the glandular layer of the endometrium, however, increased with increasing uterus weight, while the density of transected glandular tubules declined. There was no correlation between height of the stratum compactum or of the glandular epithelium and uterus weight.

5. In ewes with dead embryos the means of the following indices were significantly greater than in ewes with live ones: height of the stratum compactum, height of the glandular layer, height of the gland epithelial nuclei; the density of glandular tubules was less.

6. In the hot-room, gland epithelium height was correlated with mean rectal temperature.

7. Expansion of the glandular layer is not associated in all subgroups with more embryonic deaths and cannot therefore be their main cause. The observations do not indicate that early embryonic deaths are due to insufficiency of ovarian hormones; nor do they account for the marked improvement in viability associated with thyroxine injections.