Eight Merino and eight Dormer ewes, none of which had been on heat for 2–3 months prior to treatment, were given six intra-muscular injections of 30 mg. progesterone at 3-day intervals. The ewes were divided into four groups, each consisting of two Merinos and two Dormers. On the second day after the last progesterone injection, 1000 i.u. P.M.S. were administered to each of the ewes in group I. The remaining ewes each received an injection of 500 i.u. P.M.S. on either the first and second days (group II), the second and third days (group III), or the first and third days after the end of the progesterone treatment (group IV).

Five of the Dormer ewes, but not one of the Merino ewes, were served after the treatment. Mean ovulation rates for the four groups were 2·50, 2·75, 2·00 and 2·50, respectively, and the mean numbers of large follicles (i.e. those which were observed at laparotomy, approximately a week after treatment, to have a diameter of not less than 4 mm.) were 3·00, 2·75, 1·00 and 2·00, respectively. Contrary to expectation, it was observed that only one of the ewes (a Merino) showed evidence of a silent ovulation shortly before treatment.

It is suggested that (i) the amount of oestrogen produced by the ovarian follicles of the Merinos may have been exceptionally low, thus accounting for the non-occurrence of oestrus in these ewes, (ii) ovulation rates might be increased by greater reductions in the time between the last progesterone injection and P.M.S. treatment, and (iii) if silent heat in the Merino is rare, it may be simpler to induce coincident heat and superovulation in ewes of this breed by two injections of P.M.S. at 16-day intervals.

In a small plot experiment in which the crop was protected from rain, the application of large amounts of water to keep the soil water stress to a minimum gave very large crop yields. One-fifth of this amount of water gave 80% of the maximum yield. Small, frequent applications of water appeared to give higher yields than the same amount of water in one large application. Yield differences were due to differences in leaf areas rather than to differences in net assimilation rates.

The growth and carcass composition of two strains of mice (N- and C-strain), which had both been selected for large and small body size by Falconer, have been studied.

Differences in body weight between mice of the N-strain and their controls were apparent at birth and were fully maintained up to 30 weeks of age. The patterns of growth were similar in all three lines, although the large line grew at a faster rate than the small line, the controls being intermediate. Differences in absolute and relative rates of growth between the three lines reach a maximum from 21 to 35 days of age and declined thereafter.

Growth in the large line of the N-strain from 14 to 40 days of age was largely due to an increase in body protein and water; after this age, increase in weight was caused mainly by fat deposition. In the small line of this strain, protein, water and fat were deposited at a more constant rate during the whole growing period. Differences in rates of growth may account for the differences in the percentage composition found between mice of the large and small lines of the N-strain at the same age.

1. Ten successive trials with two Rahmany adult ewes were carried out with the aim of comparing the nutritive values of the nitrogenous constituents of some concentrates used in Egypt as supplements in summer rations (decorticated cottonseed cake, linseed-oil meal and beans (Vicia faba)) and of animal proteins (meat meal, fish meal and casein) and of barseem (Trifolium alexandrinum). Wheat straw was employed as the main roughage in the ration. Nitrogen intake for all supplements was 10·16 g./day.

2. Apparent digestion coefficients for crude protein were estimated. Casein had the highest digestibility coefficient while meat meal was the least digestible.

3. Nitrogen retention and ruminal ammonia curves are given for each period. Only three proteins, namely, barseem, cottonseed cake and linseed meal gave positive nitrogen balance at the critical level of nitrogen intake used throughout the trials. Fish meal improved nitrogen retention significantly. Meat meal and beans did not improve nitrogen retention. The addition of 70 g. starch to beans improved nitrogen retention significantly.

1. In a series of digestibility trials using two Rahmany ewes (see previous publication, el-Shazly, 1958), protein supplements in the form of concentrates, pure proteins or green roughage, supplying 10.16 g. N per day, did not affect significantly the digestibility of cellulose in wheat straw.

2. Decorticated cottonseed cake given at three different levels, i.e. 10.16, 20.32 and 30.48 g. N, did not produce a significant change in wheat-straw cellulose digestibility.

3. The digestibility of dry matter was significantly improved by all supplements used except fish meal and decorticated cottonseed cake at a level of 10.16 g. N per day.

4. Total volatile fatty acids were estimated just before feeding and at different intervals after feeding.

5. The implication of these results for microbial activity are discussed.

1. In a series of tests chicks were fed up to 4 weeks of age on a ‘purified’ diet supplemented with 10% of protein from either herring meal or condensed herring solubles.

2. The solubles alone appeared of negligible value as a protein source, but certain mixtures of solubles and meal protein proved superior to meal alone, although the levels of the essential amino acids plus cystine and tyrosine were lower in the mixture than in meal alone. The supplementary effect may possibly be due to changes in the aminoacid ratio or balance.

3. Only tryptophan improved growth and viability when free amino acids were added singly to the solubles. Simultaneous supply of all 10 essential amino acids elevated growth to about 80% of that on meal alone. A combination of tryptophan, isoleucine, histidine and phenylalanine appeared nearly as effective as the 10. Depressant effects of free amino acids at the low levels used were also met with. The chick results followed closely the predictions made from the results of microbiological assays of the amino-acid composition of the solubles, and these were in conformity with the composition of the ‘ideal’ amino-acid mixture for chicks proposed by Fisher & Johnson (1957).

4. The small weight gains of the chicks on solubles alone consisted largely of water rather than true tissue. Appetite appeared to be governed by the balance of amino acids, this appearing to be more important than the absolute levels fed. This applied to diets with heated meal as well as the solubles.

1. Attention is drawn to the enormous variations in yield experienced in commercial cotton growing under rain-fed conditions. Yields at Namulonge have ranged from 161 to 1163 lb./acre.

2. In seeking an explanation of this enormous variation past and present fertilizer trials in Uganda have failed to show that much of this variation is due to nutrient status.

3. From Manning's previous analysis of yields in relation to seasonal rainfall, over many district trials, it is evident that 20–25 in. of rainfall per season is optimum.

4. The purpose of more recent studies has been to examine the effect of distribution of rainfall within the season. Clearly the pattern of crop water requirement, also within the season, must supersede a simple seasonal concept of crop water use.

5. Experimental evidence, based on several seasons' data, led to the conclusion that evapotranspiration rates exceeding the commonly accepted figure of 0·8E must in fact occur in order to provide a satisfactory explanation of results recorded.

6. The within-season pattern of water requirement of an annual arable crop is shown to be more dependent on its state of development than on the pattern of a physical model based on calculations of energy availability.

1. The results are reported of a series of 8-day magnesium metabolism trials carried out with milking cows fed a variety of typical winter stall rations.

2. Twelve cows fed a standard ration of 15 lb. hay plus 12 lb. of a concentrate mixture containing 3 parts dredge corn, 1 part bran, 1 part decorticated groundnut meal and 1 lb./cwt. Churn 105 minerals, showed variations in the proportion of the feed magnesium excreted in the faeces of from 66·53 to 76·98%, probably reflecting individual differences in the capacity of animals to absorb magnesium.

3. Wide differences in the utilization of the magnesium in typical winter rations were observed. Mean values, with a standard error, obtained for the proportion of the feed magnesium excreted in the faeces with various types of ration were as follows: hay plus concentrates, 71·48 ± 0·94; hay plus proprietary dairy cubes, 62·15 ± 2·73%; hay, proprietary dairy cubes plus decorticated groundnut meal, 91·98 ± 1·93%; hay, silage (1) plus concentrates, 79·53 ± 0·99%; hay, silage (2) plus concentrates, 74·07 ± 4·24%; hay, mangolds plus concentrates, 74·28 ± 5·91%.

1. Three experiments are reported in which magnesium metabolism trials were carried out with milking cows that had been changed abruptly from typical winter rations to herbage cut freshly from swards at an early or at a more mature stage of growth and fed in the stall.

2. The intake of herbage magnesium by individual animals varied from 9·5 to 15·2 g./day. Much of this variation was, however, associated more with differences in the palatability and dry-matter content of the herbage offered than with individual differences in appetite.

3. The mean proportion of the ingested herbage magnesium excreted in the faeces was similar in all three experiments, being 82·3, 83·0 and 82·4% respectively. With any given sward there were, however, wide variations between individual animals in their utilization of herbage magnesium.

4. The supply of ‘available’ magnesium to animals fed cut herbage in the stall varied from 0·5 to 4·2 g./day, as compared with values of from 2·6 to 10·5 g./day obtained previously (Rook et al. 1958) with cattle fed typical winter rations. In spite of this lower intake of ‘available’ magnesium, the animals maintained a positive magnesium balance.

1. A co-ordinated trial has been carried out at twenty-six centres to study the effects of feeding different quantities of food to fattening pigs. The treatments studied were ad lib. feeding throughout, ad lib. feeding to 120 lb. live weight after which the amount of food given was restricted to 6·5 lb./pig/day and two scales of feeding according to live weight, one moderate and one severe (Table 1).

2. Food conversion was best for the pigs on the most restricted feeding scale, being 8% better than that for the pigs fed ad lib.

3. The slower growing pigs were less fat, slightly longer and their depths of eye muscle were greater.

4. The ad lib. fed pigs had higher killing-out percentages and higher weights into cure.

5. The bacon sides from pigs fed on restricted diets yielded a higher proportion of gammon and fore-end and had thicker streaks.

6. Restriction of feeds led to softer fats.

7. An economic appraisal has been made which shows that, on the basis of certain assumptions, the medium feeding scale would have led to a smaller profit per year than the ad lib. or the ad lib. restricted treatments under the price structure and system of grading prevailing during the period of the experiment.

Field experiments were carried out in north-east Scotland on potatoes to measure the responses to, and the two-factor interactions between, nitrogen, phosphate, potash and dung, and have given the following results:

1. The responses to nitrogen, phosphate and potash are quite variable from centre to centre, but the mean results show moderately large increases to all three nutrients.

2. The mean responses to both nitrogen and phosphate are the same in the presence as in the absence of dung. The response to potash is reduced by two-thirds in the presence of dung.

3. There is a general trend for both nitrogen and potash to increase the linear component of the response to phosphate and vice versa. Nitrogen and potash show practically no interaction effects.

4. Dung produces a considerably larger increase in yield in the absence than in the presence of fertilizers.

5. The nitrogen and potassium contents of the tubers show appreciable effects of the nitrogen, potash and dung treatments.

6. Suitable fertilizer dressings are suggested for potatoes grown in the absence and presence of dung.

1. Of various objective measurements carried out on six carcasses from each of the three Australian grades 1, 2 and Canner, the minimum depth of fat above the eye muscle at the quartering point distinguished the grades to the most significant extent, as would have been anticipated from the importance of finish in visual grading.

2. The iodine numbers of fat from the tissues of the steers examined were lower than those which would have been expected in English steers at a similar level of fatness.

1. Data from a long-term experiment providing information on the effects on barley of undersowing the crop with various common species of grasses and legumes are discussed.

2. There is no evidence that the yield of grain, yield of straw, 1000 grain weight or the nitrogen content of the grain was affected in any way by undersowing with any of these species.

1. An experiment was carried out at ten farms in four winters to compare the value of three methods of pen warming.

2. Complete information on weightgain was available in seventeen replicates; the average increase in weaning weight from the use of heat was 2·41 lb.

3. Information on survival was available for thirteen replicates; the average benefit from the use of heat was 0·58 pigs weaned per litter.

4. The farmers' comments showed that they considered heating to be of value.

1. An experiment with one non-laying and four laying hens was carried out. Food and water consumption was measured hourly from 06.00 to 22.00 hr. and in the same period the exact time of each excretion was noted. Determinations of water and dry matter were made on each separate excretion.

2. Each bird showed a typical pattern of behaviour in relation to the time of day when it ate food and drank water. For any one bird, variations of this pattern from day to day were small.

3. For each bird there was a highly significant relationship between water intake and temperature on the one hand, and water excretion via droppings and eggs on the other. Water intake, however, had a far greater influence than had temperature on water output.

4. Calculations showed that, despite errors caused by not knowing the amount of metabolic water produced, the excretion from the lungs varied greatly from bird to bird on constant intakes of water and also in the same bird at different intakes.

1. The frequency of excretion of droppings by hens varied considerably over the day and much of this variation appeared to be related to the disturbance of the birds by attendants.

2. Data relating to dry-matter excretions by five birds for 17 days were used to study the influence of zero hour and length of the time unit on variations in this dry matter.

3. It was found that, in this experiment, 14.00 hr. appeared to be the best zero hour, but it was suggested that, considering the heavy excretion of material around 06.00 hr. when the birds are first disturbed in the morning, 07.00 hr. might be the ideal time. Data from an earlier experiment supported this.

4. There was a decrease in variation up to a unit of time equal to 3 days and times not multiples of days gave greater variations. There were, however, considerable differences between birds.

1. Experiments were carried out in 1956 and 1957 in which milking cows were grazed at the same stocking rate, either on strip grazing or on free grazing. The cows followed balanced Latin Square designs.

2. The pastures were liberally fertilized, either with NPK fertilizer (202 lb. N, 202 lb. P2O5, 252 lb. K2O per acre in 1956 and 80% of these quantities in 1957), or with PK fertilizers (269 lb. P2O5 and 269 lb. K2O in 1956 and 80% of these quantities in 1957), and a subsidiary comparison of the effect of nitrogenous fertilizers was made in 1956.

3. At the end of the main experiment in 1956 a study of the effect of straw offered to the grazing cows was made. No supplement other than straw was offered.

4. The results in both years showed no difference in milk yield per cow due to treatments, nor in 1956 was milk yield or milk composition affected by grazing treatment, fertilizer treatment or the provision of straw.

5. In both years the live-weight gain per cow was less with free grazing. In 1956 the provision of straw increased the rate of live-weight gain. It is suggested that these differences are mainly due to gut fill.