The grading-up system, in the Ayrshire Cattle breed, whereby the descendants of non-pedigree cows enter the registered (Herd Book) population, is studied principally from three aspects: (1) its numerical importance in the population; (2) the breeding structure of herds practising grading-up, and (3) the possible genetic effect of grading-up on milk and fat yield.

Cows at various stages of grading-up are noted in an Appendix to the Herd Book. The numerical importance of the grading-up system has varied with the rate of expansion of the breed as a whole—being greatest during the most rapid expansion—but, at all times, Appendix cows have had more registered female offspring than have pedigree cows. The volume of grading-up was regulated by the number of cows in Appendix B. Some 6% of the pedigree females registered in the last 30 years have Appendix A mothers and a further 5% or so owe their existence to grading-up during the last 30 years.

On average, the proportion of herds registering bulls is not greatly different among the herds which grade-up and those which do not. Similarly, the ratio of males to pedigree females registered was about the same in both types of herd. None-theless, there appears to be considerable selection against Appendix animals in the ancestry of bulls compared with cows, and none of the large bullbreeding studs appear to pursue a grading-up policy. A greater proportion of Ayrshire herds were grading-up in Scotland than in England.

Entry into Appendix B of the Herd Book is confined to cows reaching a qualifying yield. The daughters (A) of these B cows mated to unselected pedigree bulls were found to yield significantly more in their first lactation (36 gal. milk and 14 lb. butterfat) than contemporary pedigree Ayrshire heifers in the same Scottish milk recorded herds in 1955. Part, if not all, of this superiority is thought to be genetic.

1. Two groups of pullets were reared on a 12 and a 23½ hr. day length respectively and at an environmental temperature of 64–65° F. Two months after the first bird came into lay, the day length of the second group was reduced to 12 hr. over a period of about 8 weeks (phase I).

2. Both groups came into production at the same time, but the group reared on a 23½ hr. day grew more rapidly.

3. The reduction in day length caused moulting and low production for several months, whereas the group which had been reared in a 12 hr. day continued to lay steadily.

4. Soon after the reduction of day length half of each group (subgroups B and D) was exposed to an artificial thermal autumn and winter, which had no detectable effect on production (phase II). After this the temperature was allowed to rise to 64–65° F.

5. When the day length of the remaining birds (subgroups A and C), still kept at 64–65° F., was increased to 23½ hr., there was no significant increase in production (phase III).

6. When their day length was then reduced to 12 hr., they moulted heavily and went out of production (phase IV).

7. Simultaneously the day length of subgroups B and D was increased to 16J hr. (phase IV). This had no significant effect on production.

8. The yield of the birds which had their day length reduced at the beginning of the experiment was twenty-three ovulations less than that of the others at the end of the artificial winter, and nineteen less at the end of the laying year. The laying year was concluded before phase IV. There was no difference in yield between the birds which had an artificial autumn and winter and those which lived in a warm environment.

9. Data are given on the frequency distribution of the yield after a reduction in day length, over the remainder of the year, and also on the correlation between the yields in these two periods.

10. The eggs of the group reared in a 23½ hr. day length tended to be larger than those of the other group in conformity with their larger body weight. Apart from this the various treatments had no effect on egg weight.

11. There was no relation between the egg yields and the variations in absolute and relative humidity.

12. In a subsidiary experiment it was found that, if the reduction in day length was completed a month before the birds began to lay, there was no significant effect on subsequent production.

13. In the light of these experiments it seems that the essential cause of winter pause and the annual rest, in birds given supplementary lighting, is the decline in day length in late summer and autumn.

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.

1. The findings presented in two previous papers on the yields of volatile fatty acids, obtained by the action of rumen liquor in the artificial rumen, from fresh grass, dried grass and the water-soluble and water-insoluble separates of the latter, have been amplified by a consideration of the acids similarly obtained from specimens of chemically prepared crude fibre and cellulose, from four of the dried grass specimens.

2. The proportions of different volatile fatty acids from grass crude fibre and grass cellulose resemble those obtained from cellulose powder, propionic acid being produced in greatest relative yield.

3. A general review of these latter findings, in relation to those already presented, has been given.

The literature on the protein requirements of young dairy heifers has been discussed and the wide variations noted, both in quantities estimated for particular live-weight ranges and in the suggested trends of requirements with live weight.

Short-term trials have been conducted in which the effect of variation in protein intake on rate of live-weight gain of dairy heifers of various ages was studied.

The response to increments of protein in the ration was found to be curvilinear with a rapid decline in response above critical levels of intake. This level varied with the live weight of the animal, being 0·8 lb. crude protein at 300 lb. live weight and 1·0 lb. at 400 and 500 lb. when rations based on hay, decorticated ground-nut meal and flaked maize were fed.

These levels are somewhat lower than estimates of protein requirements quoted in the literature, though the trend indicated in them agrees with some of the published data.

No marked difference was observed between the values of decorticated ground-nut meal and white fish meal as protein supplements. Urea was inferior to decorticated ground-nut meal.

The overall depressant effect of straw on rate of live-weight gain is demonstrated and discussed.

1. One hundred and sixty-eight pigs were used in four experiments to test the value of including antibiotics and copper sulphate, either as separate supplements or together in rations for growing pigs. Procaine penicillin was added at the rate of 5·36 mg./lb. diet and Aureomycin (in Aurofac 2 A) at 8·03mg/lb. and CuSO4. 5H2O as 0·1% of the diet.

2. During the growing period in Exp. 1, pigs fed diets supplemented with copper sulphate or procaine penicillin grew 9 and 3% faster respectively than the controls. Pigs fed a diet containing both supplements grew 22% faster than the controls. During the finishing period there was an outbreak of virus pneumonia and the within-treatment variability was large. There were no significant differences between treatments during this period, although pigs fed the supplemented diets tended to grow more slowly than the controls. Over the total experimental period pigs fed the diet supplemented only with copper sulphate grow 2% faster than the controls, and those fed the diet supplemented with both procaine penicillin and copper sulphate grew 4% faster than the controls, but these small average improvements were not statistically significant. In Exp. 1 treatment differences in food conversion efficiencies paralleled those for growth rates. Killing-out percentages were higher when pigs were fed the copper-supplemented diets, and lower when procaine penicillin was fed. The area of ‘eye’ muscle was increased by adding procaine penicillin to the diet.

3. During the growing period in Exp. 2, pigs fed diets supplemented with copper sulphate or with both procaine penicillin and copper sulphate grew 8 and 9% faster, respectively, than the controls. The addition of procaine penicillin had no significant effect when added as a single supplement or in conjunction with copper sulphate. During the finishing period pigs fed diets supplemented with copper sulphate, procaine penicillin, or both copper sulphate and procaine penicillin grew 5, 3 and 10% faster, respectively, than the controls, while over the total experimental period they grew 4, 0 and 9% faster, respectively.

4. Some pigs fed the copper-supplemented diets during the growing period in Exp. 2 were fed diets with no copper added over the finishing period. During this latter period the pigs grew at about the same speed as the controls, and significantly more slowly than those pigs which continued to receive copper sulphate. Thus, the average growth rates over the total experimental period were significantly slower by 3–7% when copper was omitted after 100 lb. than when it was fed to the pigs throughout the entire experiment.

5. In Exp. 2, as in Exp. 1, treatment differences in efficiency of food conversion paralleled those for growth rates. A higher rate of growth was always accompanied by an improvement in efficiency of food conversion, with about the same percentage difference between treatments. Indeed, changes in rate of growth were probably dependent upon changes in efficiency of food conversion, since all pigs were fed to the same scale based on live weight.

6. The treatment differences in killing-out percentage and area of eye muscle observed in Exp. 1 were not confirmed in Exp. 2. There were no differences in carcass quality measurements attributable to the treatments imposed in Exp. 2.

7. The livers of pigs fed diets containing copper sulphate during both the growing and finishing periods had, on average, about eighteen times the concentration of copper found in the controls. When the copper sulphate supplement was fed only during the growing period the liver copper concentrations were, on average, about four times those of the controls. However, the variation between the individual values was very large in all groups fed copper sulphate. This variation may have been caused partly by sampling errors if copper is not distributed evenly throughout the liver.

This paper provides a general review of the effect of nitrogenous fertilizers on the yields of wheat, barley and oats. The results of 270 experiments carried out during the last decade in England and Wales have been examined.

With the exceptions noted below wheat and barley crops have produced a grain response of 3·0–3·5 cwt./acre to a standard dressing of 0·25 cwt. N/acre; this agrees well with earlier results obtained by Crowther & Yates. The widely grown winter wheat varieties, Hybrid 46, Cappelle Desprez, Bersée, Nord Desprez and Atle each produced an average response of more than 4·0 cwt./acre to the standard dressing. Of the spring barleys, Kenia, Proctor and Herta are also of greater than average responsiveness. The average response of spring oats to the standard dressing was only 1·2 cwt./acre.

The number of experiments is insufficient to allow precise conclusions to be drawn on the effect of autumn dressings, but the evidence suggests that in the drier eastern counties autumn nitrogen may give as good a response as the equivalent spring application. Small dressings of nitrogen provide equal responses whether applied early or late in spring; larger applications need to be applied early in spring (March or April) to obtain the highest yields. There is no evidence that divided dressings are more efficient than a single dressing applied in early spring.

For highly responsive varieties of winter wheat and spring barley mentioned above a dressing of 0·6–0·7 cwt. N/acre is recommended, producing a net return of approximately £10 per acre. For other varieties of winter wheat, and for spring wheat and spring barley, the recommended dressing of 0·5 cwt. N/acre produces a net return of about £5 per acre.

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.

The response of calves to varying amounts of whole milk, as revealed by two experiments at the University of Reading farm at Sonning, is considered as a study of growth and development.

In the first experiment, which had been carried out between 1944 and 1951, seventy-five Shorthorn calves were divided into three groups (A, B and C) reared on 90, 65 and 40 gal. respectively. The treatments produced significant and prolonged differences in live weight.

A second experiment, carried out between 1952 and 1954, consisted of twenty-eight Shorthorn and twenty-eight Friesian calves in four groups (I–IV) reared on 100, 79, 57 and 35 gal. respectively. Very much less response to the treatments was found in live weight, and the effects on thirteen body measurements were even smaller, though still statistically significant. A marked difference in the response of the two breeds was apparent, the Shorthorns showing greater treatment effects in live weight and most of the body measurements.

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.

1. The aim of the experiment was to determine gross efficiency and net efficiency of energy conversion for milk production in lactating sows.

2. Two lactating Wessex Saddleback sows were used for both determinations. Two dry, non-pregnant sows of the same breed were also required for the determinations of net efficiency.

3. Rations were adjusted with the aim of maintaining the sows at constant live weight, but this was only partially successful.

4. Digestible energy intakes and milk energy outputs were measured during three 6-day recording periods in the 2nd, 5th and 8th weeks of lactation. Digestible energy consumed was determined by incorporating 1% of chromic oxide in the rations to be fed, and measuring the energy contents of food and faeces by bomb calorimetry.

Milk energy output was determined by measuring milk yields and compositions and calculating the energy contents from percentages of fat, protein and lactose. Milk yields were measured by weighing the young pigs before and after each suckling during each recording period, and samples were obtained by a special milking machine for determination of chemical composition.

5. Data required for the calculation of energy conversion efficiencies for milk production are presented. Gross efficiency was determined as approximately 45% and net efficiency as approximately 85%, but this latter value must be regarded more as an estimation because of the difficulty of determining accurately the maintenance requirements of lactating sows.

1. The availability of the calcium in three species of grass has been determined by a slaughter technique, using the rat as the experimental animal.

2. The calcium in both timothy and perennial rye-grass was found to be more available than that in cocksfoot, the differences between timothy and cocksfoot, and between perennial rye-grass and cocksfoot being of a significant order.

3. The grasses as a whole were found to be inferior to both the legumes and herbs in respect of calcium availability.

4. The significance of the high faecal calcium values found in rats receiving the cocksfoot diets has been discussed.

5. There was shown to be some indication of inverse relationships between fibre content and calcium availability, and between oxalic acid content and calcium availability.

No single one of the nine grassland plants so far investigated has proved to have a calcium availability which, when taken in conjunction with total calcium content, would be in the least likely to induce symptoms of deficiency in an animal fed on that species alone.

1. Results are reported from two experiments in a series to determine the optimal amount of meal to be fed in conjunction with unrestricted whey for fattening pigs.

2. In both experiments, one carried out during the summer and the other during the winter season, the same four treatments were given. The control pigs received meal ad. lib up to a maximum of 6½ lb./ head daily. Pigs on the other three treatments received whey ad lib., and either 3 lb., or 3 lb. reduced at two different stages to 2 lb. of meal per head daily. There were ten pens of nine pigs on each treatment, involving a total of 360 pigs. Comprehensive carcass measurements were made on all pigs.

3. The data obtained showed that satisfactory results could be obtained by feeding a daily allowance of 3 lb./pig of a proprietary sow and weaner meal throughout the fattening period, in conjunction with unrestricted whey. Where the utilization of as much whey and as little meal as possible was required, it was shown that a reduction from 3 to 2 lb. meal/pig/day by the 13th week of life could be made without adverse effects, apart from an increase of approximately 12 days in the time taken to reach bacon weights.

4. Carcass grading results of all whey-fed pigs were reasonably satisfactory, but both the carcass grading and general performance of the control animals was not good. Possible reasons for this were discussed.

5. Data concerning the pattern of food consumption over 14-day periods throughout the experiments were presented. Pigs given 3 lb. of meal/day throughout, or 3 lb. reduced to 2 lb./day, consumed up to approximately 3¼–3½ or 3¾–4 gal. of whey/day respectively.

The role of the skin of cattle in heat toleration has exercised many and has produced almost as manyopinions as workers. Brody (1945) pointed out that tropical cattle had a considerably larger surface area than the temperate breeds due to the looseness and folding of the skin. Bonsma, van Marle & Hofmeyr (1953) suggested on the basis of work on the Africander that a thick skin was necessary, presumably to repel the heat rays. Other workers have laid stress upon hair colour and thickness of coat, together with skin pigmentation. Worstell & Brody (1953) considered that cattle do not sweat, but Dowling (1955 a, b) found evidence that they did.

The extent to which spring barley crops lodged at Rothamsted increased with seed rate and with nitrogen, and was much more severe in the wet summer of 1954 than the dry one of 1955. Although in 1954 all plots were extensively lodged by harvest there were great differences in date of lodging; 50% of the area was lodged later in plots sown with 1 than with 3 bushels/acre, the delay being 8 days with 1½ cwt. sulphate of ammonia, 14days with 3 cwt. and 21 days with 4½ cwt. The weight of unit length of the basal part of the straw was reduced by higher seed rate and to a smaller extent by nitrogen.

Yield of total grain was only slightly affected by treatments; yield of dressed grain was decreased by higher seed rate in 1 year and by nitrogen in both years.

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.

The paper presents the results of 10 years of soil moisture studies in arabica coffee in high altitude tropical conditions. Very deep soils and contrasting wet and dry seasons give unusually favourable conditions for soil moisture measurements.

Volumetric measurements on soil cores are reported for 10 ft. depth of soil, which is shown to include most of the root system of arabica coffee, and holds 48 in. of water under field conditions when active drainage has ceased. This is shown to correspond to a soil moisture tension of 1/3 atm. Of the 48 in. of water only 12 are available to plants. Wilting points determined by sunflower seedlings on soil samples to 15 ft. depth are shown to agree well with field sampling under wilting conditions in coffee plantations.

A series of seasonal factors relating the water use of the coffee crop to the readings of an evaporation pan are presented, and their application over 6 years is shown to check with soil sampling data within the limits of sampling error. This method is proposed for control of supplementary irrigation under conditions of limited water supply, but a distillation-type radiation integrator can with advantage replace the evaporation pan.

The balance of the hydrological equation for this crop is demonstrated in each of the 6 years.

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.

During recent years increasing use has been made of carcass measurements to assess differences in the conformation, growth rates and carcass quality of bacon pigs. The measurements usually taken are: (a) thickness of back fat at one or more points, (b) thickness of flank at one or more points, and (c) the length of the carcass. Whilst at present there is fairly general agreement as to where the back-fat and flank measurements should be taken, the same agreement is not found in the case of carcass length.

1. Two experiments involving length measurements of ninety-six bacon-pig carcasses showed that chopping out the backbones, chilling and laying the carcasses down on a table, each resulted in a decrease in average length. There was variation from carcass to carcass in the magnitude of these decreases which, in the case of the chopping out the backbone and laying down stages, was related to the fatness of the carcass, greater decreases being found in the longer, leaner carcasses than in the shorter, fatter sides.

2. Estimates of the precision of measuring showed that length from the junction of the first rib and the sternum to the symphysis pubis taken on hanging carcasses was less susceptible to errors than the same measurement taken on the lying carcass, and that both these measurements were more accurate than that from the atlas bone to the symphysis pubis taken on carcasses either hanging or lying.