In the inbred lines of a flock of Brown Leghorns, it was noted that the line means for albumen weight ranked in the same order as those for shank width. The parallelism was not due to the large differences in body weight existing between the lines.

It was established that variations in albumen weight were more closely associated with changes in shank width than were those of yolk weight. It is possible, but not definitely established, that shell weight follows the behaviour of albumen in this respect.

The histochemical localization of acid and alkaline glycerophosphatase (phosphomonoesterase) has been determined throughout the reproductive tract in the bull. Sections were incubated in a buffer substrate containing sodium β-glycerophosphate at pH 4·5 and pH 9·4. Duplicate sections were incubated for progressive lengths of time ranging from ½ hr. (alkaline phosphatase) to a maximum of 48 hr. (acid phosphatase).

Evidence of the presence of both enzymes has been obtained in the tissues which compose the reproductive tract. In the case of acid phosphatase the reaction was predominant in the nuclei of the lining epithelial cells. In addition, a positive cellular reaction was found in the distal portions of the epithelium lining the epididymis, the ampulla of the vas deferens and the seminal vesicles. The reaction obtained in the testis appeared to vary with the stage of activity of the tubule.

In the case of alkaline phosphatase the reaction was predominantly shown by the basement membrane and the capillaries throughout the tissues with a cellular reaction in the distal portions of the cells lining the epididymis, the ampulla of the vas deferens and the seminal vesicles. In the seminal vesicles the type ‘A’ cells reacted strongly while the periphery of the osmic staining vacuoles of the type ‘B’ cells also gave a positive reaction. The only activity present in the prostate was in the capillary endothelium. The spermatogenic epithelium showed a positive reaction, but no reaction was given by the interstitial cells.

(a) Measurements made on sides of bacon exhibited since the war at the National Pig Breeders' Association carcass shows at Stirling and Peterborough and on various commercial sides have been analysed to investigate differences between the shows, the years and the sexes.

(b) In the Large White exhibits the sides from gilts were on average longer, thicker in the belly, thinner in back fat and with better developed eye muscles than the sides from hogs.

(c) The area of the eye muscle of the carcasses entered in these shows between 1948 and 1952 shows an unexplained decrease over this period. The width of the eye muscle is the only character showing a definite show difference, being larger at Stirling than at Peterborough.

1. The relations of yolk, albumen and egg weight were studied in seven inbred lines of Brown Leghorns and reciprocal crosses of two of these lines.

2. In all the lines the eggs produced by hens had a bigger proportion of yolk than those produced by pullets.

3. Besides changes in both components accompanying differences in egg size the line means for albumen weight still differ significantly after adjustment is made for its covariance with yolk weight. This independent variation leads to differences in the yolk-albumen ratio of the hens.

4. Within the lines there is a significant negative association between egg size and the yolk/albumen ratio.

5. The wide differences in egg size, dividing the pure lines into two groups characterized by large and small eggs respectively, resulted from a marked decrease in the amount of albumen in the eggs of the latter group. Yolk weights, on the other hand, could be ranked in a fairly regular series with adjacent lines differing by 2 g. or less.

6. There is some source of variation in the yolk/ albumen ratio for line means which is not accounted for by differences in egg size.

The investigations that have been in progress at the Grassland Research Station, Stratford-on-Avon, on the management of grassland for the production of winter pasturage are discussed as four experiments, E 62, E117, E 86 and E158.

Exp. E 62 was concerned solely with herbage production, while the remaining three have taken into account the performance of the beef animal under such pasture treatment.

The maintenance of condition in the animal has proved possible over a number of winter seasons from 1948 to 1953, sufficiently so to warrant investigation of the means of providing as abundant pasturage as possible at this time of year from latesummer and autumn rested swards. The importance of integrating a system of winter utilization with summer production has become evident in the course of the work, and the necessity of upkeeping sward condition, more especially the grass-legume balance, has been realized. The use of alternate drills of grass and lucerne shows considerable promise in this respect. Intensive utilization and production has taken place from such seedings at all seasons without serious sward deterioration.

The development of a grazing system for outwintering cattle destined to be fattened on summer pastures would provide a means whereby such cattle would be fed with as little attention and labour demand as is consistent with good stock management. With the need for cheapening of costs in beef production methods in Britain attention might well be paid to the methods outlined in the light of the experimental data presented.

1. The relationship existing between the gross digestible energy content and the chemical composition of 24 hays has been studied with nine Cheviot wether lambs over a period of 8 months.

2. Each hay was fed to a group of three lambs for a 10-day preliminary and 10-day collection period. Faeces and urine were collected in metabolism crates.

1. The respiration rates of three 4-month old Ayrshire bull calves were measured in individual 6 hr. daily exposures to 15, 20, 25, 30, 35 and 40° C. dry bulb temperatures at 17 mg./l. absolute humidity and at 7 mg./l. saturation deficit at temperatures of 30, 35 and 40° C. in a planned sequence of environmental temperature. The schedule of experiments on each animal lasted 45 days consisting of five replications of these nine environmental conditions. Throughout the experimental programme the respiration rates of these three animals and of three control animals were measured in a holding room just before the experimental animal of each pair was transferred to the hot room.

2. The frequency of respiration of all the calves increased with increasing environmental temperature and humidity.

1. An investigation has been made into the changes that take place in the free amino-acid pattern when kale-water slurries are allowed to ferment under conditions of (a) aeration, (b) anaerobiasis and (c) partial sterilization with sulphur dioxide.

2. It has been found that, with aerated mixtures, the loss of free amino-acids is virtually complete within 2 weeks, while there is only a slight loss with the anaerobic mixtures. With mixtures containing sulphur dioxide no loss of amino-acids occur.

3. The formation of α-amino butyric acid possibly from threonine has been noted.

1. Dissections were carried out on lambs, and the skin was found to be supplied by numerous small arteries fairly evenly distributed, but often in series along the body. In several instances these arterial trunks were traced back through the body muscles to various main arteries.

1. The results of six trials have been examined in which pigs received rations with contrasting levels of crude fibre. The contents of crude fibre ranged from 3½ to 11½% and were related to a variety of basal diets.

2. The main object of the trials was to study the effect of increased levels of dietary crude fibre on carcass conformation, under conditions where there was no disparity in rate of live -weight gain between the pigs receiving the higher and the lower level of fibre. Thus pigs on the high-fibre diets received extra food in order to equalize the intake of digestible nutrients.

3. The results indicate that a rise in the level of dietary crude fibre was accompanied by a fall in the killing-out percentage, and hence by lower carcass weights. This effect was produced even by comparatively small changes, such as a rise from 3½% crude fibre to about 5% crude fibre. The results also show that carcass weight was positively correlated with back-fat thickness to a marked degree.

4. It is evident that raising the level of crude fibre in the food caused a change in the distribution of live-weight gains, so that when at the same slaughter weights, the high-fibre pigs had lighter carcasses and heavier offal than their low-fibre counterparts. Consequently the high-fibre pigs also had thinner back-fats, and they would tend to grade better under carcass grading systems based on backfat measurements and biased towards thin back-fats.

5. It is suggested that these effects are likely to be produced even in pigs considerably advanced in fattening, and that in younger pigs the drawback of retardation in rate of live-weight gain may also be encountered. Thus the use of high-fibre diets in self-feeding systems, as a corrective against over-fatness, may not normally be the best means of attaining this objective under commercial conditions.

The ages of the Clun ewes considered in the survey were ranged from between 1 and 4 years in practicbreeding ally every case. They had thus not attained their maximum fertility which probably occurs at the age of from 4 to 6 years. A consideration of the fertility in the breeding flocks does not provide an estimate of the maximum for this breed, which can only be obtained from older draft ewes which are used in crossbreeding flocks with the object of fat lamb production.

Barrenness is relatively unimportant in ewes, but affects approximately one-third of all breeding ewe lambs each year. Abortion was insignificant amongst ewes but was more common amongst ewe lambs.

1. The heart rates of 4-month-old Ayrshire bull calves were measured in individual 6 hr. daily exposures to 15, 20, 25, 30, 35 and 40° C. dry bulb temperatures at 17 mg./l. absolute humidity and at 7 mg./l. saturation deficit at temperatures 30–40° C. The schedule of experiments on each animal lasted 45 days and consisted of five replications of these nine environmental conditions. Throughout the experimental schedule the heart rates of three paired control animals were measured in a temperature-controlled holding room.

2. The heart rates of all experimental animals increased with increasing environmental temperatures above 20° C. and with increasing humidity above 30° C.

1. The rate of passage of ova down the Fallopian tubes in the pig has been checked on eighteen living sows by laparotomy and in fifteen sows and gilts at autopsy.

2. Both sets of observations suggest that the ova enter the uterus between 24 and 48 hr. after ovulation instead of 72 hr. as suggested by earlier workers.

3. It is suggested that the rapid passage of ova through the Fallopian tubes of the pig may be facilitated by the progesterone from the large number of corpora lutea in the ovaries of the pig.

Part I

1. Reasons are given for expressing the evaporative loss of the resting fowl in the following way:

where C is a constant, f(tr) is a function of rectal temperature, ps is the vapour pressure of a saturated atmosphere at the temperature of the evaporative surfaces, and pa is the vapour pressure of the ambient air.

2. It was found that for practical physiological purposes the rectal temperature may be taken as that of evaporation, from which ps, is deduced. The real temperature of evaporation is probably a few degrees below this, as would be expected.

3. It is concluded from this, that atmospheric humidity hinders the evaporative cooling of fowls less than that of men. Therefore, a farmer cannot estimate the comfort of his fowls in hot weather from his own subjective impressions. The experiments also explain theoretically, why evaporative coolers for poultry houses are successful in practice.

PART II

1. The evaporative loss over a wide range of rectal temperature is plotted in Fig. 1. By applying formula (ii) it was possible to prepare curves for 28 and 5 mm. Hg atmospheric vapour pressure. These vapour pressures are near the extremes of absolute humidity, which fowls naturally encounter in hot climates. Brown Leghorns were used, and it is pointed out that the results with other breeds might not be quite the same.

2. It was calculated that part of the increase in evaporative cooling in hyperthermia is due to the rise in temperature of evaporation. At high rectal temperatures its importance is comparable with that of increased pulmonary ventilation.

3. There was no significant sex difference in the relation between evaporative loss and rectal temperature (Fig. 2).

4. The maximum possible evaporative cooling of fowls in equilibrium with their environment was 41 Kg.cal./sq.m./hr. at a humidity of 28 mm. Hg atmospheric vapour pressure and 64 Kg.cal./sq.m./hr. at 5 mm. This is much less than the maximum attained by man and somewhat less than that of the dog. Although evaporation per unit surface area was less than in the cow, it was much the same in relation to metabolic requirements.

5. Next, certain discrepancies are considered in the relation between rectal temperature and evaporative loss (Tables 3–5). At rectal temperatures near the panting threshold evaporation was found to be greater at high air temperatures and during the night. For the night tests fragmentary data only were available. These findings are tentatively attributed to a lower normal body temperature, which lowered the panting threshold.

1. Nitrogen transformations during the decomposition of straw composted with ammonium carbonate have been studied by following the changes in (a) the amounts of inorganic and organic nitrogen; (b) the amounts of ammonia-, volatile base-, α-amino- and amino sugar-N liberated by acid hydrolysis of the organic nitrogen complexes; and (c) the amino acid composition of acid hydrolysates of the composts.

2. Synthesis of organic nitrogen during the biological decomposition of straw composted with ammonium carbonate is not accompanied by any gross change in the distribution of the forms of organic nitrogen. A large fraction of the organic nitrogen synthesized is in the form of protein; a smaller fraction is in the form of amino sugar.

1. Trials over 2 years involving 120 Half bred ewes were conducted in outdoor paddocks with controlled feeding. A study was made of the effect of varying the level of feeding during pregnancy on production of ketonaemia and pregnancy toxaemia.

2. Blood ketone levels were low and pregnancy toxaemia absent in ewes gaining weight during the latter part of gestation, but ewes failing to gain weight over the same period were subject to ketonaemia and pregnancy toxaemia. A reduction in the ration of fat ewes for a 3-week period, imposed more than 5 weeks before lambing, had no detrimental effect.

3. A significant correlation was found between loss in weight and highest ketone figure in the highthroughout and the high-checked groups in 1952 and in the high-checked-high group in 1953.

4. High ketonaemia was not always indicative of pregnancy toxaemia, since of the twenty-nine ewes which had, on one or more occasions, over 20 mg. β-hydroxybutyric acid per 100 ml. blood, seven showed signs of pregnancy toxaemia and twentytwo did not.

5. In the cases reported, the time of appearance of the first symptoms of pregnancy toxaemia was around 14 days from the estimated lambing date, and affected ewes tended to lamb before term.

6. On a comparatively low level of nutrition, only one case of pregnancy toxaemia occurred, though some animals had marked ketosis. In well conditioned ewes reduced to a similar level during the critical period, there was a high incidence of pregnancy toxaemia, and in most of these cases a high degree of ketosis.

A study has been made of the reactions of three breeds of sheep (Blackface, Cheviot and Wiltshire) to four different environments. Evidence was obtained that these breeds react differently to these different environments. No changes in rank occurred but the Blackfaces grew relatively faster on a good plane of nutrition than the other two breeds. Their wool production on a sample area was also relatively greater, due primarily to an increase in diameter of the non-medullated fibres. These differences indicate fundamental physiological differences in reaction to environment.

In the course of two breeding seasons 261 mature Romney ewes have been employed in three slaughter experiments designed to investigate the manner in which the reproductive performance of such animals, after treatment with a single injection of P.M.S., is conditioned by: (a) the amount of P.M.S. administered; (b) the nutritive status of the treated animals; (c) the stage of the oestrous cycle at which the P.M.S. is administered.

In the first experiment, one untreated control group and three experimental groups of ewes, treated with different amounts of P.M.S., on the twelfth and thirteenth days of the cycle, were used to establish a dose level-ovulation response relationship. Mean ovulation rates and ranges of ovulations observed were: control 1.17 (1–2); 250 i.u. P.M.S. 1.50 (1–2); 500 i.u. P.M.S. 2.07 (1–3); 1000 i.u. P.M.S. 4.33 (1–13).

In the second experiment, oestrous cycle lengths, ovulation and conception rates, and loss of ova during the first few weeks of pregnancy were compared in four groups of ewes that had been treated as follows: (a) neither flushed nor treated with P.M.S.; (b) flushed but not treated with P.M.S.; (c) not flushed but treated with 650 i.u. P.M.S. on the twelfth or thirteenth days of the cycle; (d) flushed and treated with 650 i.u. P.M.S. on the twelfth or thirteenth days of the cycle.

Oestrous cycle lengths were of significantly shorter duration in flushed than in unflushed ewes (0.5 day) and in P.M.S.-treated than in untreated animals (0.7 day). Conception rates were of a normal order in all four groups. The mean ovulation rates of those that conceived at first fertile service were respectively 1.33, 1.61, 1.80 and 1.88. The number of ovulations ranged from 1–2 in the unflushed–untreated group and from 1–3 in each of the other three groups.

In the third experiment results obtained from groups of ewes treated with 650 i.u. P.M.S. on the tenth, eleventh, twelfth, thirteenth and fourteenth days respectively, were compared. Mean ovulation rates were approximately similar in all five groups, but (as was also the case in the second experiment) of a lower order than might have been expected from the dose response curve established in the first experiment. Conception rates were satisfactory after injection on the twelfth, thirteenth or fourteenth days, but unsatisfactory after treatment on the eleventh day, and still less satisfactory after treatment on the tenth day.

From the results obtained in these three experiments the following general conclusions were drawn:

(1) Breed or strain differences may be of considerable importance in governing the extent of the ovulation response following P.M.S. treatment.

(2) The magnitude of the ovulation response to P.M.S. treatment depends to some extent on the ‘batch’ of P.M.S. used and/or the strain of ewes employed.

(3) The nutritive status of ewes during the breeding season is not an important factor in determining the ovulation rate following P.M.S. treatment.

(4) When P.M.S. is administered 5 days or less before the onset of the subsequent oestrus, good conception rates are obtained.

(5) Extremely poor conception rates result where animals are treated more than 5 days before oestrus.

(6) Best ovulation and conception rates are obtained when the treatment-to-oestrus interval is 2–3 days.

(7) For optimum results, treatment on the fourteenth day of the cycle is recommended. However, good results are also obtained after treatment on either the twelfth or the thirteenth days. Treatment on the fifteenth day should also be reasonably satisfactory.

(8) When ovulated in similar numbers, and provided conception occurs, ova produced as a result of P.M.S. stimulation are no more prone to fail to undergo normal embryonic development than are naturally ripened eggs.

Migration of pedigree Ayrshire cattle in the British Isles is estimated for 1927 and 1946 from samples of herd-book registrations. Most migration is from Scotland, particularly Ayrshire, to England, but considerable numbers were also transferred between regions within Scotland or England. A larger proportion of bulls than of cows was moved in this way. Only a small proportion of animals had two parents bred in the same herd as themselves. If the males and females registered from England in 1946 were the sole parents of the next generation, the latter would still have more than half Scottish blood.

The amount of movement of Ayrshire cattle shown by these data virtually precludes genetic differences between regions, but not perhaps between herds. Other implications of movement are discussed.

It is suggested that part of the increased permeability of soil recently ploughed out from grass could be due to water conduction through the severed roots. Microtome sectioning of a root of Lolium perenne showed a continuous metaxylem element of about 30μ diameter, with only minor restrictions, forming a natural capillary tube. Further, being at the centre of the stele, the metaxylem should persist for some time after the grass has been killed. Hydraulic diameters calculated from laboratory experiments on the rates of water conduction by severed L. perenne roots were in reasonable agreement with the diameter of the metaxylem measured by direct sectioning.

Similar experiments on Phleum pratense were more difficult to interpret due to the complexity of the metaxylem, the number of elements not being constant along the root. The rate of water conduction by roots of Dactylis glomeratus was found to be small compared with the other grasses, for although having the largest number of elements they are the smallest in size of any grass examined.

The permeability of a severed Lolium perenne root system, calculated on the basis of the surface density of roots found on 4-year-old plots, indicated that the root system should significantly increase the unsaturated permeability of soil at low suctions. To obtain maximum benefit the ‘capillary tubes’ should be severed immediately under the turf and not at ploughing depth. Accordingly, two plots were laid out on old grassland to compare normal autumn ploughing with shallow rototilling on the subsequent germination and growth of spring wheat. In spite of repeated rototilling, however, it proved impossible to kill the grass in the wet winter conditions and the wheat was smothered. A comparison of the suctions developed at 5 cm. in the two plots showed that the unsaturated permeability of the rototilled plot was higher.

Although the laboratory results are encouraging there is as yet no conclusive evidence that the natural water supply and drainage system formed by the severed roots is important under field conditions.