Hairiness in wool of Suffolk sheep as a fault was found to be associated with other defects like coarseness of wool fibres, hairiness of the britch, and the occurrence of pigmented fibres. The presence of these various defects was studied in the lamb's tail at docking time, and subsequently evaluated and correlated with the fleece.

The tails were graded according to the nature of the fibres and the spread of halo hairs from the tip to the base into four principal grades which by further subgrading could be made into seven grades. The results were as follows:

(1) There was wide variability in grades of tails within each flock.

(2) Average grade of tails followed in general the mean quality of the adult fleece.

(3) When Border Leicester were crossed with Welsh Mountain the tails of the two reciprocal crosses were found to be of hairy type of tail and nearly like the Welsh Mountain type.

(4) The percentage of coloured tails in the least hairy grades was found to be inversely related to the quality of the tail grade and indirectly to the fleece quality.

(5) The diameter of the wool fibres on the base of the tail is highly correlated with the diameter of fibres from the britch regions or mean fibre diameter from four regions of the body (mid-shoulder, midside, hip and britch).

(6) The mean diameter of the wool fibres obtained from four different parts of the tail was correlated with those of the britch regions only.

(7) The diameter and variability of fibres increased from shoulder to britch in the body and from base to tip in the tails.

(8) The britch and tails of two groups of sheep, one group characterized by coarse and the other by fine britch and tail wool, were studied histologically. There were significant or highly significant differences in the following characteristics in the britch of the two groups: (a) total number of follicles, (b) primary follicles with no medulla, (c) total number of secondary follicles, (d) secondaries with no medulla, (e) secondaries with large medulla. The only type of follicle where a significant difference was found in the tail was in the number of secondary follicles with no medulla.

1. Five pairs of Suffolk twin lambs were used and one of each pair was injected twice daily with 2 mg. of a growth hormone preparation for 2 weeks.

2. Treatment was begun when they were between 3 and 4 weeks old, the total number of follicles in the Suffolk not being complete until 6 weeks old. Skin samples were taken at the beginning and end of the experiment.

3. It was found that in 0·25 sq. cm. of skin the total number of primary follicles was reduced from the beginning to end of the experiment in both control and treated groups, probably because of the expansion of skin area during that time. While the total number of secondary, ‘news’ and ‘plug’ follicles was also reduced in the control group, they were increased in the treated group.

4. Since the secondary to primary follicle ratio was 5·3:1 for the treated group as compared with 4·5:1 for the controls it is concluded that growth hormone increases the number of secondary follicles which develop during the early weeks of postnatal life.

1. Three experiments were carried out in this study to investigate the effects of L-thyroxine on sheep and wool production. In the first experiment L-thyroxine was orally administered to ewe lambs from weaning time for a period of 48 weeks. In the second experiment, ten uniform yearling ewes were selected and were randomly distributed into two groups of five; one group was fed daily 7 mg. L-thyroxine per ewe for 7 weeks from 1 April 1954. In the third experiment L-thryoxine was fed as a supplement to lactating ewes over the second to the sixteenth week of lactation at the rate of 7 mg. daily per ewe.

2. Differences in both body weight and rectal temperature between the experimental and control groups were not statistically significant. The treatment had also no effect on the body weight of the ewes during lactation.

3. Wool growth, as measured by the weight of keratine production per unit of surface area, was increased significantly during the period of thyroid treatment. This increase in wool production was due to an increase in the length of the wool fibres but not to any observable increase in the diameter of the fibres. This effect is different from that produced by a high plane of nutrition where extra wool production is characterized by increase in both length and diameter.

4. It was observed that the treated ewes exhibited hypersexual activities characteristic of male behaviour, i.e. jumping and mounting other animals.

5. There was a significant increase in the rate of milk secretion over the period. 2–8 weeks. This increase was reflected in an improved live-weight increase of the lambs which were suckling these treated ewes. The difference in milk yield between treated and untreated ewes was not maintained over the nine to ten weeks period of the lactation.

6. As a result of these studies it has been established that the normal milking performance of Border Leicester × Scotch Blackface ewes is high as compared with that of other breeds or crosses reported in the literature. The shape of their lactation curve suggests, however, that it is possible that after the eighth week of lactation the ewes may become competitors with their lambs for available grazing. Expressed in another way ewes become less efficient as converters of their food into milk for lambs, for which milk is becoming proportionately a less important component of the diet. This finding raises the question of the possibilities of providing creep grazing or supplementary feeding for lambs so that their growth potential is fully realized. Alternatively, there may, under farm conditions, be grounds for weaning lambs at about 12 weeks so that they may have preferential treatment in regard to available grazing rather than to adopt customary weaning at about 16–18 weeks of age.

7. It has been established that a close relationship exists between the milk yield of dams and the growth, rate of their lambs under normal grazing conditions. Because of this strong relationship a regression formula has been tentatively advanced which may permit workers to select ewes for milk yield on the basis of the live-weight gain of their lambs.

The distance between the front of the incisor teeth and the front of the maxillary pad (incisor bite measure) was measured in 140 sheep about 1 year old. The sheep consisted of seven breed types—the offspring of Blackface ewes by Wiltshire, Border Leicester, Lincoln and Blackface rams, and of Welsh ewes by Welsh, Wiltshire and Suffolk rams. Within each breed type the effects of four different feeding treatments lasting 7 months were studied. These produced small but very significant differences in bite measure. Differences between breed types were significant only in respect of the division between the two breeds of dam. Effect of breed of dam, however, was confounded with any effect due to differences in origin.

The proportion of permanent central incisors which had replaced milk teeth when the animals averaged a little more than a year old was affected both by the level of treatment during the experiment and by breed.

1. Pot culture experiments are described comparing the recovery of nitrogen, and sulphur by the difference and ‘labelled atom’ methods and the recovery of carbon by the latter method. Italian ryegrass was used as the test crop with ammonium sulphate, calcium nitrate and urea as the fertilizers.

2. The recovery of fertilizer nitrogen was less using the ‘labelled atom’ technique than the conventional difference method.

3. The recovery of sulphur from ammonium sulphate ‘labelled’ with 35S was measured. It was considerably less than the nitrogen, but not inconsiderable especially as a basal dressing of ‘unlabelled’ K2SO4 was applied.

4. Using urea ‘labelled’ with 13C there was no evidence that any of the carbon was in the ryegrass four weeks after application.

The physiology of lactation in mice was studied in those aspects which were relevant to selecting mice for milk yield. The investigations fall under five headings.

Activities of lactating mice. From continuous records of the diurnal activities of mice, it was found that lactation causes no disarrangement of the mouse's day; both nursing and non -lactating females spend about 70% of their day on the nest, during which time the young are continually sucking; 20% of the day is spent at the food basket; and the remainder is divided equally between drinking and wandering about the cage. As her lactation advances, the female spends a smaller portion of each day on the nest, and the periods of nursing become shorter but more frequent. The lactating female spends no longer than the non-lactating female in feeding herself.

There is a slight rhythm, repeated daily, in the fraction of successive 4 hr. periods spent on the nest; the rhythm is the inverse of that for locomotory activity; and neither is as strong as the rhythm Bullough has described for locomotory activity in males.

Regulation of milk production according to litter size. Milk production is imperfectly proportional to the number of young suckled and is independent of the number of young born. Maximum amount of milk is available when the litter is born, and the supply is rapidly and permanently cut down to the requirements of the litter. The regulation is by partial involution of secreting tissue in all mammae.

Regulation presents difficulties in using litters of different sizes to measure lactation, and a method is given of constructing a chart whereby the relative performances of females suckling different sizes of litters can be compared.

Competition among suckling young. Although the mammary glands of any female are not equally developed, the apportionment of milk among her litter is usually fairly even, at least as far as this can be judged from the weights of her young at 12 days. This implies that young mice show no preference each for a particular teat and are constantly jostling each other for every teat. It seems, however, that when litter mates differ in the birth weights, in the unbalanced competition that results, the larger mice do get the greater share of milk. If the competition depended on any form of violence, it should be greatly reduced in small litters. Since there is no evidence of this, it is concluded that the competition is passive, i.e. that the larger young get the greater share of the milk because they feed faster, and not because they oust their weaker sibs from the best glands or spend longer sucking them.

Relations of lactation to body weight and age. Lactation performance of a mouse is correlated with her weight even when this is measured as early as 12 days of age. The correlation is no more pronounced when the measurement of weight is delayed until mating, i.e. only shortly before lactation. Evidence is given that different mechanisms are responsible for the correlations with earlier and with later weights. The earlier correlations demonstrate the inheritance of lactation performance from mother to daughter and the effect of the mother's lactation on her daughter's weight. This maternal effect on body weight diminishes in older mice, but inherent determination of weight increases. Thus the correlation of lactation with later weights arises from pleiotropy of gene action, and perhaps receives a contribution from effects of the environment that the two ‘characters’ have in common.

Lactation performance is also correlated with age, but only through the greater weight of older mice. Age seems to have no independent effect on lactation, e.g. on the development or efficiency of the mammary glands.

The role of crude fibre in modifying the general equation relating the digestibility coefficient of crude protein to the percentage of crude protein in the dry matter of a feed is described.

It is shown that for normal average food-stuffs the effect is slight and that for all practical routine purposes the original equation will provide satisfactory estimates of the digestibility coefficient when only the crude-protein content of the dry feed is known.

On the other hand, when exceptional feeds are encountered, particularly those in which the crudefibre/crude-protein relationship is abnormal, then more accurate estimates of the digestibility coefficient of crude protein can be obtained from the modified equation which is described above.

Twenty-one field experiments were carried out from 1953 to 1955 on main-crop potatoes to compare dressings of nitrogen applied wholly to the seedbed (as ammonium sulphate), with equivalent dressings applied partly to the seedbed (as ammonium sulphate) and partly as a top-dressing (of ‘Nitro-Chalk’) just before the final ridges were set up.

In this paper a detailed examination of the rate of transfer of riboflavin to the embryo during incubation is reported.

Confirmatory evidence of the direct effect of egg content of riboflavin on subsequent growth of the chick is supported by liver analyses for riboflavin. Changes in the liver content after hatching show that after 10 days on a low riboflavin diet reserves of chicks reach a minimal level irrespective of original egg content.

The data for the rate of transfer of riboflavin to the embryo show a direct relationship between the amount reaching the embryo and the initial content of the egg. Evidence is presented of a large rate of transfer at the most critical period of development, which is at 14–15 days as judged by embryonic mortality in riboflavin deficiency. In eggs containing low levels of the vitamin a relatively small amount of the vitamin reaches the embryo at this critical 15-day stage.

The time required for hens on a low dietary level of riboflavin to reach maximal egg levels is shown to be of the order of three weeks.

The utilization by the embryo of riboflavin injected into the egg is studied quantitatively. The injected vitamin is as fully utilized by the embryo as is riboflavin deposited at egg formation.

Qualitative chromatographic separation of the flavines of fertile eggs during incubation shows a gradual increase in combined forms as development proceeds.

Reference is made to the depression in hatching rates occasionally recorded when fishmeal is fed to breeding hens. In a previous communication this depression was tentatively ascribed to the presence of aerobic sporing bacteria, support for this theory being given by the high early death-rate from yolksac infection in the chicks hatched from the affected pens. In this experiment samples of white fishmeal from widely separated points of origin were employed. With one group of birds extreme hatching depression was recorded; in one other group a moderate depression was found. Bacterial assays showed that only one sample contained aerobic sporing bacteria capable of coagulating yolk and the count was not high. But the birds fed this sample were those manifesting the mild depression in the hatching rate and this was the only group to show an appreciably above normal early death-rate in the chicks. The major cause of death was yolk-sac infection, and it is concluded that in this group the presence of aerobic sporing bacteria was partially responsible for the depression in hatching, but that the degree of contamination was not as high as that which probably occurred in the previous year.

The hatching rate in all groups was inversely related to the depth of coloration in the fishmeal samples. The theory is advanced that, as a result of overheating during manufacture, degradation of the proteins occurred giving rise to toxic products which in turn led to a high embryonic death-rate during the last 4 days of incubation. The highest embryonic death-rate in total, and during this period, was found with those birds fed the fishmeal with the darkest colour. The egg production in all groups of birds was high and it therefore seemed improbable that overheating had proceeded to the stage of materially damaging the essential aminoacid contents of the meal, for it seems widely accepted that if the amino-acid level is sufficient for egg production it is sufficient for good hatchability.

1. Laboratory incubation studies with topsoil samples of the Kikuyu red loam coffee soil have shown that active nitrification of the natural soil nitrogen stops at a soil moisture level just below the permanent wilting percentage. Ammonification of natural nitrogen in this soil does not cease at this moisture level and ammonia nitrogen accumulates substantially, although the values found at the end of the 32-day incubation period, and the rate of ammonification are significantly lower as the moisture level is decreased from ⅚ to of the permanent wilting percentage.

1. Four replicated experiments were made to determine the rate of passage of meal through the alimentary tract of pigs on different feeding treatments. In each experiment stained meal was used and the results were expressed by means of excretion curves. From these, mean retention times (R values) were calculated. All the curves were of a similar sigmoid shape.

2. A significant inverse relationship was found between the mean retention time and the total weight (meal plus water) of the ration. This relationship was found when (a) the weight of meal was constant and the weight of water was varied, (b) the weight of water was constant and the weight of meal was varied, and (c) the total combined weight of meal and water (at the same ratio) was varied.

3. The digestibility of the dry matter and crudec protein in Exps. 1–3 was not altered greatly as a result of the different feeding treatments.

4. In Exp. 4, similar rates of passage were found in pigs fed on the two rations of widely different digestibilities.

5. The dry-matter content of the faeces of the pigs was remarkably constant over a wide range of water and food intakes when using the same meal.

The possibility was examined of supplying vitamin A to chickens from the first days of life as carotene in green plants. Growth experiments were carried out with chickens till the age of 8 weeks. Different kinds of forage (horse-beans, Berseem clover, green oats, sweet potato leaves, cow-peas, corn-leaves) were given in quantities calculated to supply 300 μg. carotene per 100 g. feed; control groups received fish-liver oil, given at the level of 500 i.u. per 100 g. feed. Weight gains and extent of vitamin A storage in liver served as an indication of the utilization of carotene from different sources. The utilization of carotene from all the plants examined was sufficient to support normal growth, only in the groups receiving clover was growth found to be somewhat slower. Remarkable differences were found in the extent of liver storage, and that was taken as an indication of differences in activity of the carotene from the different sources.

Attempts to determine the reasons for these differences in liver storage capacity of the carotene from the various plants did not reveal the presence of any plant components enhancing or depressing vitamin A storage.

Similarly, no correlation could be found between digestibility coefficients of carotene in the different plants and liver vitamin A storage. This correlation seemed likely in sweet potato leaves only, the rather low digestibility coefficient found in these leaves may account, at least partially, for the low activity of this plant.

The stereoisomeric composition of the β-carotene of the different plants and the xanthophyll/carotene ratio are very similar in all plants tested and cannot account for differences in carotene activity of the plants studied.

The results of this work show that it is possible to satisfy the requirements of chicks for vitamin A from the first days of life by supplying certain forage plants. In practice, because of the variability of the carotene content in such plants, care has to be taken when estimating the amounts to be given. Green plants should be given to chickens freely or at least in liberal amounts.

1. The reflex ejaculation responses of cocks to lumbar massage have been examined, and some basic reactions described. A list of the crude fluid components obtained by the massage technique of semen collection is given.

2. From these observations, and a chemical test on the contents of the hen's vagina after natural and artificial insemination, it was deduced that the normal ejaculate of the cock is composed mainly of contents from the vasa deferentia, with some secretions from the mucosal glands of the vascular bodies and lymph folds. The blood plasma transudate sometimes expelled into the semen is obtained as a result of compression of the terminal organs during the collection procedure.

3. Points emerging from the observations on ejaculation, and the search for the normal constituents of semen are discussed.

Equipment for milking sows by machine and the technique employed are described.

The writer wishes to express thanks to Mr H. S. Hall, of the National Institute for Research in Dairying, for assistance in the selection of suitable teat cups, and to the Avon India Rubber Co. Ltd, for kindly supplying the liner tubing.