The average yields of irrigated long-staple cotton in the three-course rotations: dura, fallow, cotton, D-F-C; lubia, fallow, cotton, L-F-C; and fallow, fallow, cotton, F-F-C, were studied over 12 years in an experiment in the Sudan Gezira; the fallows (resting land) were either hoed or were left uncultivated during the rainy season, so that the effects of the operation of hoeing on the subsequent cotton yields could be measured.

Where the fallows were unhoed L-F-C yielded more cotton than F-F-C, which gave at first higher yields than D-F-C, although this difference had disappeared by the end of the period. Fallow hoeing increased yields in all rotations; this response was maintained in D-F-C and L-F-C. In F-F-C the response to hoeing either fallow diminished steadily in time and whilst the higher response to hoeing both fallows also decreased, its rate of decrease was no greater than when only one fallow was hoed. The response to hoeing fluctuated considerably from year to year. In all rotations these fluctuations were associated with rainfall and the relationships have been expressed in the form of regression equations; separate equations were necessary for each rotation as the relationships were quite distinct.

The variety X1730 A out-yielded Domains Sakel. There were interactions between the varieties and the other treatments, but these interactions were such that the varieties differed more at higher levels of yield and did not modify the above conclusions appreciably.

An artificial rumen is described which has been shown to simulate closely conditions in the bovine rumen. Criteria of its validity include quantitative and qualitative bacteriological data, V.F.A. production, pH levels and digestion rates; these were examined with a variety of diets using cows on similar diets as controls. An important feature of the apparatus is the high degree of control which can be exercised over the progress of the in vitro ruminal fermentation, permitting experiments of considerable duration.

1. Ten manurial treatments were applied annually to cattle cabbage grown in a six-course rotation for 7 years. Samples were taken in the early winter each year, and from five harvests taken at fortnightly intervals in the last year.

2. The dry-matter yields each year closely followed the weather conditions during the growing season. There was no significant fall in the dry-matter yield during the last season. The treatments supplying phosphorus or phosphorus and potassium substantially increased yield, but the application of nitrogen did not.

3. The application of nitrogen, potassium or phosphorus increased the levels of these constituents in the crop in practically all cases. The application of phosphorus produced hearted plants which contained significantly less dry matter than the openleavod plants produced in its absence. The levels of ether extract, crude fibre, ash, silica and magnesium wore not significantly affected by the manorial treatments.

4. There was little variation in composition as the season advanced except for significant increases in the crude-fibre levels and decreases in the nitrogen-free extractives levels.

5. The distribution of the chemical components was investigated in the outer leaves, heart leaves and stem of the plant. This was compared with that in the marrow-stem kales.

6. The chemical composition of the cattle cabbage compares fairly closely with that found for the marrow-stem kales grown under similar conditions. It is, however, lower in dry matter, crude fibre, magnesium and chlorine. It may be considered as a replacement for marrow-stem kale as a source of crude protein and all the major minerals except chlorine and possibly magnesium.

1. A co-ordinated trial has been carried out at eighteen centres to study the effects of feeding various quantities of high-protein supplement to growing-fattening pigs. In treatment 1, 10% white fish meal was included from weaning to 150 lb. live weight and 3% soya-bean meal was included from 150 lb. live weight to slaughter (approximately 210 lb.). Treatment 2 was the same as treatment 1 except that only 7% white fish meal was included during the first stage. Treatment 3 was the same as treatment 2 except that the rations were changed at 1001b. live weight instead of 1501b. Treatment 4 was the same as treatment 3 except that highprotein supplement was omitted altogether after 1501b. live weight; thus there were three rations involved in treatment 4—7% white fish meal from weaning to 100 lb. live weight, 3% soya-bean meal from 100 lb. to 150 lb. and no high-protein supplement thereafter.

2. Growth rate and feed conversion both differed significantly between treatments. Pigs on treatment 1 grew 5·0% faster than those on treatment 4; the average growth rate for treatments 2 and 3, the difference between which was negligible, was 3·3% higher than for treatment 4. Feed conversion for treatment 1 was 5·4% better than for treatment 4 and the average for treatments 2 and 3 was 3·8% better than for treatment 4.

3. Treatment differences were not significant for killing-out percentage, length, quality of fat, proportions of gammon, middle and fore-end of the cured side, thickness of streak, size of eye muscle and amount of fat over it. Some of the fat measurements differed significantly between treatments; differences in fat thickness at the shoulder, middle and rump between treatments 1, 2 and 3 were generally small, but the lowest protein level (treatment 4) resulted in carcasses with about 2% more fat along the back than the average of treatments 1, 2 and 3. These slight differences in back-fat thickness did not result in significant differences in the percentage of pigs in the highest grades.

4. An economic appraisal of the results suggested that under the conditions prevailing at the time of the experiment treatment 3 would have resulted in the greatest profit per year, and the greatest profit per pig. This ration was relatively cheap compared with those of treatments 1 and 2 but it did not lead to a seriously impaired performance, as did that of treatment 4, the cheapest ration.

An analysis has been made of the reproductive rates and milk yield of Kenana cattle in a closed dairy herd in Sudan.

The average age at first calving was 38·4 months and calvings were most frequent between September and December.

The average length of productive herd life of cows was 5·42 lactations.

The average interval between successive calvings was 395 days, and this was influenced by years and age.

The mean generation interval was 6·72 years.

The average milk yield in 224 days was 338 gal. with a standard deviation of 152 gal.

There was a close relationship between milk yield and lactation length; r = 0·866 ± 0·013.

Milk yield increased by age until the fourth lactation when it was about 137% of the first lactation. The rate of increase in yield between first and second lactation was highest and amounted to 22%.

Year of record had a pronounced effect on milk yield.

Month of calving had a slight effect on milk yield.

The repeatability estimates of single records milk yield, calving intervals, lactation periods and dry periods were 0·432 ± 0·046, 0·058 ± 0·059, 0·192 ± 0·058 and 0·069 ± 0·065, respectively.

The increase in repeatability estimates between earlier and later successive milk yield records was accompanied by a decrease in the coefficients of variation of these records.

The heritability of a single record milk yield was 0·239 ± 0·245.

The rate of annual genetic superiority in milk yield of dams of cows and dams of bulls was found to be 0·74% of the herd average.

1. Activity of Lumbricus terrestris, Allolobophora caliginosa and A. chlorotica was unaffected by 15 mg. hexoestrol in solution in 500 g. soil.

2. Activity and reproduction of A. caliginosa was unaffected by 10 mg. hexoestrol in 500 g. soil, but 100 mg. and over affected activity and stopped reproduction.

3. Egg capsules of A. caliginosa and A. chlorotica developed normally in a saturated aqueous solution of hexoestrol.

4. No effect on the soil fauna of grass plots due to grazing with implanted bullocks was observed.

This paper describes an experiment designed to test the goitrogenic effect of white clover (Trifolium repens L) in ewe lambs grown and taken through a complete reproductive cycle. The sheep were setstocked on four pastures made up of perennial ryegrass and short-rotation rye-grass, both alone and together with cyanogenetic white clover. Since these species differ in iodine content when grown on the same soil, there were probably differences in dietary iodine intake of the sheep in the four groups. Half the animals in each group were injected intramuscularly with an iodinated poppy-seed oil to serve as an iodine depot.

At slaughter, 19 months from the commencement of the experiment, thyroid weights indicated a goitrogenic action in the non-injected ewes grazing short-rotation rye-grass and white clover and to a lesser extent in the non-injected ewes grazing perennial rye-grass and white clover. There was evidence of a slight goitrogenic action in noninjected ewes grazing perennial rye-grass. The thyroids of non-injected ewes had similar iodine contents, lying within the range of 0·23–0·29% of the dry weight.

In injected ewes, the total iodine content of the serum was three to four times higher than with non-injected ewes and the iodine content of the thyroids was three times greater. All injected ewes had thyroids of normal weight.

No effects of iodine supplementation on growth, reproduction or wool production were found.

Lambs born to the ewes in the fifteenth month of the experiment were slaughtered when 3–5 months old, the age varying with pasture treatment. Thyroid weights indicated a goitrogenic effect from the clover-containing pastures.

1. Ammoniated sugar-beet pulp has been compared with decorticated ground-nut meal, when added to a control diet low in protein, in feeding trials with seventy-five cows on three farms and in a balance experiment with four cows.

2. In the feeding trial the cows receiving decorticated ground-nut meal gave 8·4 lb. more milk weekly than cows receiving the control diet. Cows given the diet in which the molassed sugar beet pulp in the control diet was replaced by ammoniated sugar beet pulp gave 7·9 lb. more milk weekly than the control group. The milk-fat percentage was not affected by the treatments. Slight increases in solids-not-fat percentage resulted in an increased yield of solids-not-fat with both high-nitrogen treatments. The increases in milk yield approached statistical significance and the increases in solidsnot-fat were significant.

3. It was concluded that the feeding trial showed that the nitrogen added to sugar-beet pulp during ammoniation could be utilized by milking cows, but the experiment did not permit an estimate of the efficiency of utilization.

4. In the nitrogen balance experiment the utilization of nitrogen was measured as the sum of milk nitrogen and the nitrogen balance. It was concluded that 29·5 g. of nitrogen from 0·8 lb. decorticated ground-nut cake increased the daily utilization of nitrogen by 12·9 g., whereas 55·7 g. nitrogen from 8 lb. ammoniated sugar-beet pulp increased the utilization by only 6·0 g. In this experiment the efficiency of utilization of the nitrogen from groundnut meal was 44% and of the ammonia nitrogen from ammoniated sugar-beet pulp only 11%.

5. Ammoniation raised the crude protein content of molassed beet pulp from 10 to 20%. If for the computation of rations the content of digestible crude protein in sugar-beet pulp is taken as 5·0%, that in the ammoniated pulp should be approximately 7·5%.

6. If given in sufficient amounts the ammonia nitrogen had as great an effect as the nitrogen of ground-nut meal in correcting the effects of a diet low in protein.

1. The digestibility of diets supplemented with fat has been investigated.

2. For adult fowls and young chicks an increase in the fat content was accompanied by a decreased digestibility of the supplemental fat.

3. Supplemental fat depressed the digestibility of the carbohydrates when added to a chicks' diet, but had no such effect on a layers' diet.

1. Records collected on the steers reared during the long-term experiment on beef production on the Cambridge University Farm from 1946 to 1955 have been analysed to examine the relation of live weight to various body measurements and the dependence of these relations on breed, treatment and age.

2. Among the measurements considered singly, chest girth was most closely related to live weight.

3. There were marked differences in the slopes of the regression lines relating log live weight to log chest girth during the two phases of the experiment—from birth to 8 months of age and from 8 months to slaughter.

4. The regression coefficients in the first period were affected by the treatment on which the calves were being reared. Those in the second period were affected both by the level of feeding the steers were receiving during that period and by the manner in which they had been reared to 8 months.

5. Height at shoulder was the measurement which, as a second variate in the regression equations, led to the greatest increases in the accuracy of prediction of live weight. However, the relation of this measurement to live weight was also affected by the treatment.

6. It was considered that these measurements show little promise as estimators of live weight which could be generally applied, since their relations to live weight were affected by the treatment of the animal.

1. The potency of balancing interactions between the protein of herring press-cake (dried) and solubles (condensed) on one side, and certain vegetable feeds on the other, has been examined on 2- to 4-week-old chicks:

(a) Initially by comparing the co-effect of a series of different combinations of the herring products when ingested together with certain cereals plus extracted ground-nut meal, to that estimated earlier when the same combinations of herring products formed the sole dietary protein.

(b) Thereafter by studying whether the co-effect of the herring products was influenced or not by substituting extracted soya-bean meal for the ground-nut meal.

(c) Further by tentative trials to show that registered interactions were caused by some keystone amino acids.

2. A special dietary system was devised for the purpose (a basal diet of actual feeds + a synthetic, practically protein-free basal diet + the tested feed, eventually + adjustments), the results being recorded as combinative protein value = c.p.v.

3. Interactions between dietary constituents not only were shown under the circumstances, but proved to be an easily acting factor of great power. Herring solubles in proportions of 15–45% were formerly found to bring about a statistically significant improvement of the meal when fed together with this as the only protein of the diet. But: (a) the introduction of certain cereals and ground-nut readily converted the beneficial effect of the solubles into a significantly negative one. (b) Whereas soya-beans instead of ground-nut evidently reversed the situation again. In this third grouping solubles at moderate levels appeared neutral, meaning that herring solubles combined significantly better with soya-bean than with ground-nut when fed to young chicks in presence of a set of cereals and herring meal, (c) Responses to supplemental, crystalline amino acids showed that the interactions between the protein sources could be attributed to their constituent amino acids. Thus the little efficient combination of solubles and ground-nut plus certain cereals could be greatly improved by small quantities of all ten essential amino acids together, and equally much by lysine plus threonine only. Contrarily, the diet appeared weakened when lysine, threonine or isoloucine were omitted singly or together from the whole ten. The same was the case with single addition of leucine.

4. The discussion stresses the pre-eminent importance of the diet in biological estimations of protein value. It also points out the practical significance of skilful combination of different protein sources.

Twenty semen samples were collected by means of the artificial vagina from three Friesian and two Dexter bulls. In each sample, the head length and head breadth of spermatozoa which did not take up the nigrosin-eosin stain, and their percentage before and after 72 hr. of preservation in egg-yolk-citrate and egg-yolk-glycine, were studied. The following results were obtained from the study:

1. No significant variation was found in the two measurements of sperm head before and after preservation in E.Y.C.

2. Both the head length and head breadth of spermatozoa preserved in E.Y.G. were significantly less than those before and after preservation in E.Y.C..

3. The change in size of the spermatozoa head in E.Y.G.. dilutor may be due to an alteration in the acrosome.

1. The formation of a herd of Northern Frontier Zebus for genetical research has been described.

2. Details are given of the system of mating used and the type of management adopted.

Thanks are due to Dr J. W. B. King of the Animal Breeding Research Organization, Edinburgh, for his advice, to Mr M. A. Witcomb for taking the photographs, and to the Directors of the East African Veterinary Research Organization and the East African Agriculture and Forestry Research Organisation for their encouragement.

1. The estimation of milk yield in a herd of suckled zebu cattle has been described.

2. Milk yield was found to be relatively stable when compared with weight at calving and subsequent live-weight change.

3. Under constant conditions, there was a negative correlation between milk yield and live-weight change in the cows, compared with a positive correlation when both characters were affected by seasonal changes.

4. Variation in milk yield was reflected in the growth rate of the calves, but considerably greater quantities of milk were required to increase growth without the aid of extra grass.

5. It was concluded that, under the present conditions, calf growth rate could be increased more efficiently by the improvement of nutrition than by selection for high milk yield in the dams.

1. The efficiency of food conversion of Brown Leghorn fowls inbred for egg number, or egg size, or egg number and egg size have been compared.

2. Comparison between the lines was made for egg numbers, total egg weight and total egg energy. Egg energy was the best measure of production, total egg weight was the next best and egg number the poorest.

3. When allowance was made for differences in rates of egg production and egg size, there were no differences in the efficiency of conversion of food to eggs between the lines.

4. The standard errors of the means for the analytical data on the twelve replicate mixes of the diet were relatively small, but the range in values was appreciable. The importance of analysing diets in nutrition experiments is stressed, particularly for ‘iso-caloric’ diets.

1. The normal sweat glands of twenty-eight calves, nineteen live adult cattle and eighteen slaughtered cattle from temperate breeds were examined. In every animal the lumen of the sweat glands contained a fluid-like material.

2. It appeared on examination and rough measurement that the size of the sweat glands taken from animals after slaughter was smaller than that of the glands taken from live animals even when the same sampling technique was used for both.

3. The sweat glands of sixteen calves were examined before and at intervals after the animals had been subjected to a hot environment. The glands were always seen full of a fluid-like material.

4. It is concluded that if the calf sweat gland is stimulated by heat stress it must function either (a) by simple diffusion through the sweat gland wall and hence to the skin surface, or (b) by a secretory process not involving degeneration of the glandular epithelium. It is probable that at least part of the contents of the lumen of the sweat glands is derived from the epithelium by a process of active secretion.

1. A small-scale plot experiment which had been conducted from 1947 to 1952 to study the effect of massive dressings of fertilizer nitrogen, with and without phosphate and potash, on the yield and quality of a rye-grass dominant sward was continued from 1953 to 1958 with two changes in the mineral treatments in 1953. A 4 × 4 Graeco-Latin square was used.

The nitrogen treatments applied each year were: (1) no nitrogenous fertilizer, (2) 260 lb. nitrogen, (3) 520 lb. nitrogen and (4) 416 lb. nitrogen per acre per year.

The mineral treatments were: (A) no mineral fertilizer, (B) 336–504 lb. K2O per acre per year depending on nitrogen treatment, (C) 101–202 lb. K2O and 81–101 lb. P2O5 per acre per year depending on nitrogen treatment, and (D) no mineral fertilizer after 1953, although K2O and P2O5 had been applied during the previous 6-year period.

All the fertilizers were applied in four or five equal dressings each year, one for each cut.

Treatments 1 and 4 were cut four times and treatments 2 and 3 five times per year.

2. Applications of phosphate did not affect the yields of herbage dry matter or crude protein, but yields were severely depressed in the absence of potash. With adequate potash the yields under all nitrogen treatments were maintained for the 6-year period and were at the same level as in the previous 6-year period. The mean yields of dry matter for the 6-year period when potash was applied were 5200, 8420, 10,180 and 9700 lb. per acre per year for treatments, 1, 2, 3 and 4. Without potash the corresponding mean yields were 5460, 6410, 6210 and 6880 lb. Average crude protein yields were 760, 1360, 1940 and 1660 lb. per acre per year with potash and 780, 1100, 1220 and 13201b. without potash.

3. The weighted mean contents of crude protein for the 6-year period averaged over all the mineral treatments were 14·4, 16·7, 19·4 and 18·2% for nitrogen treatments 1, 2, 3 and 4. The mean crudeprotein contents of treatments with and without potash were 16·7 and 17·6%, respectively.

4. The average response to nitrogen was 15·0, 10·9 and 12·4 lb. dry matter per 1 lb. of nitrogen applied on treatments 2, 3 and 4, respectively, compared with a no-clover sward, and 7·8, 7·3 and 7·9 lb. compared with a grass + clover sward. The recovery of nitrogen in terms of crude protein was 45, 40 and 40% for treatments 2, 3 and 4, respectively, when compared with a no-clover sward.

5. The botanical composition of the plots continued to be determined by the nitrogen and potash treatments. On plots receiving ‘Nitro-Chalk’ clover was virtually non-existent, whereas on plots which received potash and no nitrogen, clover was present. With a combination of potash and nitrogen vigorous swards of timothy were found but if only nitrogen and no potash was applied, poorer grasses, such as Festuca rubra, were dominant.

6. Soil analyses showed increased pH values and decreased contents of Mg with increasing applications of ‘Nitro-Chalk’. P2O5 values were low except where phosphate was being applied. The most marked change was in the K2O values which varied from 4 units on treatments A and D which received no minerals to 40 units on treatment B which received the heavy dressings of potash.

7. Mineral analyses of the herbage for 1953 and 1958 are given. High K contents were found on treatments where potash was applied and this was associated with decreased Mg and Na contents.

8. Some details are given of a field-scale trial on the Institute farm where high levels of nitrogen and potash have been applied for 11 and 12 years with successful results.

1. Three trials are reported in which the grazing behaviour of separate groups of cows, one receiving supplementary food, either as conserved roughage, concentrate or fodder crop, was observed over 24 hr. periods. A fourth trial, assessing the effect of summer temperatures on unshaded milking cows, is briefly described.

2. In trials 1 and 2 the stall feeding of either conserved roughage or concentrate reduced grazing as compared with unsupplemented cows by approximately 10%.

3. Allowing access to a fresh ‘strip’ of a fodder crop at a set time each day, whilst not altering total grazing time, very markedly altered periodicity of grazing. Cows delayed grazing up to 3 hr. whilst awaiting a fresh ‘strip’.

4. Environmental temperatures up to 87° F. did not alter total grazing time as compared with grazing time when temperature reached a maximum of only 70° F.

5. The value of supplementary feeding of dairy cattle at pasture, at least where the intake of pasture is sufficient for maintenance and a low level of production, appears to be open to question.

Groups of Rhode Island Red chicks were fed a mash made up from East African feedingstuffs or that diet supplemented with a high level rate of aureomycin—97 g. aureomycin hydrochloride per ton of feedingstuff. The chicks were kept on wire for 8 weeks. The initial improved growth rate of the chicks fed the aureomycin supplemented feedingstuff was not maintained, nor was there any statistical indication that the addition of aureomycin improved the feed conversion rate.

Although the mortality rate appeared to be very much lower in the chicks fed the aureomycin supplement, the evidence was too limited to allow this to be attributed solely to the effects of the aureomycin.

The experiment illustrates the need for careful design in order that the effect of the factors to be tested may be separated from the effects of other factors contained in the experiment and not confounded with them. Moreover, advanced statistical analysis should be used as an invaluable aid to, but not a substitute for, visual or graphical examination of results, for such examination often yields valuable indications of possible lines of analysis and may avoid the drawing of unjustified conclusions.

1. Field experiments are described in which the absorption of radioactive strontium by rye-grass and lucerne has been investigated during 1958 on five soil types which represent a range in exchangeable soil calcium content. 89Sr was applied as a spray to both arable land and to established pasture.

2. Absorption was reduced by a factor of up to 4 in rye-grass (shallow rooted) following ploughing to 11 in. compared with leaving the contamination on the soil surface. These results are compared with those obtained in an earlier series of experiments in 1957.

3. The ratio of 89Sr to calcium was highest in crops grown on soil low in calcium (2 m-equiv. Ca per 100 g. extracted with N-ammonium acetate).

4. The addition of lime reduced absorption of 89Sr from the soil only when the exchangeable soil calcium content was relatively low. Some effect was observed in soils containing 7–8 m-equiv. Ca/100 g., a considerably larger one in a soil containing 2 m-equiv.

5. Only small differences occurred in the ratio of 89Sr to calcium between lucerne and rye-grass. This comparison was not made beyond the first 6 months of growth.

6. Experiments carried out with established pastures on four soil types indicate that 89Sr is more readily absorbed from the ‘plant-base’ than after incorporation with soil. Ploughing and reseeding may reduce the ratio of 89Sr to calcium in herbage by a factor of up to 4. This effect may be greater on mature swards.

7. The liming of contaminated swards reduces the ratio of 89Sr to calcium in herbage by a factor of 2 to 3 regardless of the calcium content of the soil, and liming followed by ploughing and reseeding by a factor of 3 to 7.