Eggs from Light Sussex hens were weighed before incubation started and on the 19th day of incubation to determine weight loss when incubated at 40% B.H. compared with 70% R.H. They were allowed to hatch and the day-old chicks were weighed.

Although the eggs incubated in the drier atmosphere lost more weight, their hatchability was no less than the eggs incubated in the wetter atmosphere. The hatched live weight of the chicks from the respective groups did not differ significantly.

The comparatively good hatch obtained here and in part I at the 40% R.H. is suggested as being an indication that for optimum hatchability large eggs may require lower humidity than small eggs.

Investigations on the effect of seed rates and cutting treatments on the inflorescence formations and yield of seed were carried out on S. 100, S. 184 and Kent wild white clover during 1957–60 at Cambridge. The study of primordial development under field conditions, establishment of the major characters contributing to the final yield and the factors affecting their contribution were the main object of these investigations.

These factors and their relationship and contribution to the final yield results are discussed in some detail.

Reasons were sought for the changes in hatchability associated with varying frequency rate observed in part I and by other workers. All deadin-shell from the hatches of part I were examined and classified into a number of categories. Their varying incidence in relation to the control hatches was taken to indicate the effect of the rates of turning investigated, viz. 0, once in 2 days, 2, 6, 12, 24 (control), 48, 96, 144, 192 and 480 turns per 24 hr. to the end of the 18th day of incubation.

At the observed optimum rate of turning (96x) mortality was reduced throughout the incubation period with the greatest reduction occurring towards the end; the incidence of malpositions and malformations was reduced as was the case of embryos with no obvious cause of death.

The observed decrease in mortality and hence increase in hatchability at the optimum rate of turning was attributed mainly to the probable improvement of the embryo's physiological environment.

1. A general survey of the histological changes of the fore-stomachs of the lambs from 46 days of foetal life to 77 days of post-natal life is presented.

2. In all the rumen foetal specimens the mucosal surface was smooth. At birth small, conical papillae were visible and from this age onwards these papillae increased rapidly in size and tended to be long and tongue-shaped in appearance. Little change occurred in the appearance of the rumen papillae after 56 days of age.

3. The outlines of the reticulum reticular ribs were visible in the 100-day-old foetal specimen. At birth the normal honeycomb-like structure of the reticulum was well developed, but the papillae on and between the reticular ribs were small and had rounded tips. From 20 days of age onwards the reticulum features increased in size and the papillae became pointed in shape.

4. At 46 days of foetal life the omasum wall was folded to form developing laminae and by 70 days of foetal life laminae of four orders were present. The main age changes in the appearance of the mucosal surface from this age onward was an increase in the length of the laminae, the formation of small conical papillae on the laminae, and an increase in the inter-laminae spaces.

5. All three fore-stomachs showed the same general histological changes with age. The epithelium changed from a stratified cuboidal type in the foetal specimens to a keratinized, stratified, squamous epithelium in the post-natal specimens. The basal layer of the epithelium became folded to form papillae, reticular ribs and laminae, and in the rumen and reticulum further folding of this layer took place to form papillary bodies.

1. A study on the effects of the type of diet on the histological development of the fore-stomachs of the lamb is presented.

2. The rumen papillae were well developed in a 7-week-old lamb that had been fed solely on milk from birth, but compared to a lamb of the same age that had access to lucerne chaff from birth, they were smaller in size and more conical in shape. There was no difference in the appearance of the rumen mucosal surfaces of two lambs of 13 weeks of age, one of which had access to lucerne chaff from birth and the other access to lucerne chaff for only 4 weeks prior to slaughter.

3. The type of diet appeared to have little effect on the appearance of the reticulum mucosal surface.

4. The appearance of the omasum mucosal surface was only normal when lucerne chaff was fed to lambs.

5. The histology of the rumen wall was normal in the milk-fed lamb. However, compared to the lamb of the same age that had been fed on lucerne chaff, the papillary body formation, stratum granulosum and stratum corneum were less well developed.

6. Apart from a thinner stratum granulosum and stratum corneum, the histology of the reticulum wall of the milk-fed lamb was little different from that of the lamb of the same age that had been fed on lucerne chaff.

7. The histology of the omasum wall of the 7-week-old milk-fed lamb was very similar to that found in the lamb at birth.

1. The relative nutritive value to the unweaned calf of concentrates-with-hay and of grass cut from pasture in spring was measured.

2. No significant difference was found in liveweight gain or increase in body measurement between calves receiving these feedingstuffs.

3. There was some indication that rumen development, as measured by belly girth, may have been affected by the diet.

4. There was no interaction between the type of dry food consumed and the milk ration or housing conditions.

5. Results indicate that good quality grass, free from parasitic infestation, is capable of replacing hay and concentrates in the diet of the unweaned calf.

A muscle biopsy technique was employed in an experiment designed to assess the effects of hexoestrol implantation on 2-year-old and 6-year-old Aberdeen Angus steers under New Zealand grazing conditions. This paper reports the results concerning live-weight gains, carcass weights and detailed analyses of samples of m. semitendinosus and associated subcutaneous fat.

There was some evidence of an adverse effect of the biopsy operation on the older, less tractable, animals, despite the observation of no apparent effect of repeated muscle biopsies in a preliminary trial with sheep.

Hexoestrol implantation, of four 15 mg. pellets for the 2-year-old steers and six 15 mg. pellets for the 6-year-olds, led to significant increases in live weight gains during the later part of the trial only, and reduced the dressing-out percentage of the younger animals. Although there were indications of a positive response in carcass weight to hexoestrol implantation, it was concluded that, under the conditions of this experiment, implantation of relatively large dosages was not economically justified in terms of increased meat production.

Absorption of the implanted pellets varied from 42 to 85% of the total dosage, but evidenced little association with live weight changes.

Deposition of subcutaneous fat appeared to be reduced under the hormone treatment, but the responses in this respect of the 6-year-old steers were highly variable.

1. Calves which had been reared for 12 weeks on three milk feeds and either cut grass or concentrates-with-hay, were introduced to an all-grass diet when weaned.

2. Eight animals were kept indoors and fed herbage cut from paddocks grazed by nineteen similar calves.

3. After an initial period of about 2 weeks there was a tendency for grass-reared calves to make slightly better live-weight gains.

4. No difference could be shown in the intake of herbage dry matter by these groups of calves.

5. There was little indication that grass-reared animals digested their food more efficiently. It appeared that they converted grass to animal tissue better, but further study is required to substantiate this.

1. In a population of Hereford crossbred steers carcass conformation was measured by weighing wholesale joints cut in London and Home Counties fashion and dissecting a single rib sample joint. Correlations were calculated between weight of joints and certain linear carcass measurements.

2. Weights of individual joints in a group of good cuts were studied in relation to carcass composition estimated from sample joint dissection. Carcass fatness at constant carcass weight was correlated positively with some joints and negatively with others. A thigh width measurement was related to the weight of these joints in a similar fashion. This accounted for the low value of thigh width as an index of the proportion of good cuts.

3. The weights of joints, and many of the measurements, were highly correlated with carcass weight. When carcass weight was allowed for, partial correlations were too low to support the use of linear measurements to predict weight of joints in individual carcasses.

1. In an experiment designed to study some of the factors influencing the role of clover in grassclover swards fertilized with nitrogen at different rates, botanical studies of the sward were made each spring and autumn. The methods used, and the results obtained in the autumn studies, are described in this paper.

2. Full details of the experimental treatments and design, and the yield results have been reported previously.

3. The botanical composition of the sward depended to a far greater extent on the variety of grass than it did on the variety of clover included in the seeds mixture. This was true also of the yields from the different swards.

4. Some relationships are suggested between the yield and nitrogen response results and the variations in the botanical composition of the sward attributable to the variety of grass included in the seeds mixture.

5. Kersey white clover appeared to be more persistent than S. 184 and S. 100 where fertilizer nitrogen was applied to the sward, although no differences in persistency were noted in the absence of applied nitrogen.

6. A statistical study of the botanical data obtained indicated that the intensity of sampling employed gave the optimum balance between variance and time expenditure, since only a slight reduction in variance would have been obtained if double the number of samples had been taken.

The results of the grassland experiments show that as a straight nitrogen fertilizer urea was, on average, slightly less effective than the conventional materials. In the majority of individual experiments there was no significant difference between the yields from urea and those from ‘Nitro-Chalk’; on the other hand, in a very few experiments the urea yields were much lower. The arithmetic means of the averages in each series of grassland experiments indicate that urea gave total yields about 93% of those from ‘Nitro-Chalk’ and the average response (i.e. difference from control) from urea was about 85% of that from ‘Nitro-Chalk’.

The available data for cereals are considerably less than for grassland but here again there is an indication of the infrequent slightly lower efficiency of urea.

On kale the results are confusing. At times urea was safe but in one experiment heavy dressings incorporated in the seed-bed caused serious damage.

1. The effects of the addition of a non-ionic, anionic or cationic detergent to a diet containing 10% added fat on the digestibility of the protein, fat and carbohydrate have been studied.

2. The non-ionic detergent aided the digestion of fat, but protein and carbohydrate digestibility were unaffected.

3. An anionic detergent slightly, and a cationic detergent seriously, impaired the absorption of fat, and the cationic detergent also had an adverse effect on carbohydrate digestion. Neither affected protein digestion.

This paper reports various investigations of the effects of meteorological factors on the yields of crops in England and Wales. The investigations were undertaken primarily with the objects of seeing (a) whether variations in temperature had any direct effect on yields, and (b) whether Penman's concept of actual transpiration gave a better measure of the overall effect of rainfall than the use of a multiple regression on variates representing total rainfall and its distribution.

The effect of temperature and its seasonal distribution on the yields of wheat on various plots of the classical wheat experiment on Broadbalk field at Rothamsted was studied in conjunction with rainfall and its seasonal distribution, using the regression method devised by Fisher. Variations in temperature were found to show no effects on the final yields.

The relationship between actual transpiration and yield was investigated for the Broadbalk field and for sugar beet and potatoes, using average yields determined by sampling methods, for various districts in England and Wales. For sugar-beet virus yellows infection, and for potatoes blight attack, were also taken into account.

No relationship between actual transpiration and wheat yields on Broadbalk field was found, but sugar beet and potatoes both showed a positive association between actual transpiration and yield except for sugar beet in the Spalding area, where there is a high-water table. Actual transpiration was in general more effective than a regression on total rainfall and its distribution accounting for variations in yield. As might be expected virus yellows and blight also account for a good deal of the variation in yield.

1. In the seasons of 1957 and 1958–59 a total of 130 ewe lambs were used to investigate the effects on growth and sexual development of high and moderate planes of nutrition during the rearing period.

2. The nutritional treatments imposed had significant effects on rate of growth; puberty occurred at an earlier age in high-plane than in moderateplane lambs. Also, in 1958–59, four moderateplane lambs failed to exhibit oestrus during their first winter of life.

3. Puberty occurred at a significantly lower live weight in moderate-plane than in high-plane lambs.

4. In lambs slaughtered after first oestrus, ovulation rate was not significantly affected by nutritional level, nor was the number of ovarian follicles greater than 2 mm. in diameter. However, high-plane lambs tended to have more follicles less than 2 mm. in diameter than moderate-plane lambs.

5. In 1958–59 the ovarian response to a subcutaneous injection of 800 i.u. of p.m.s. was investigated in half the lambs from each nutritional treatment. Injections of p.m.s. caused a marked increase in ovulation rate over the uninjected control level but there was no difference in response between nutritional treatments. Pregnant mare's serum did not alter the size distribution of ovarian follicles.

Over the 3 years of the experiment the salt in the top 2 ft. of the soil was reduced by almost a half of the original amount, and nearly all this was removed in the first season. The movement was downwards, and there was little evidence of any upward movement; flushing was not very effective in removing salt from the soil. The type of cultivation affected the amount of salt removed, deep subsoiling being most successful with over 50% removal, but irrigation without any cultivation removed 29%. The penetration of irrigation water was very restricted in the first waterings, but became increasingly deeper as the experiment continued.

Crop yields showed a steady improvement from season to season, the final average of about 1500 lb. per feddan being above the average for the district. The various treatments did not appear to have much effect on the yields, and the general improvement in yields is attributed to the reduction of salt content and to the deeper water penetration, chiefly the latter. The detrimental effect of the dry north winds was more apparent than the effects of the different treatments.

1. An experiment was conducted at Jealott's Hill from 1945 to 1956 to study yield trends of cereals grown continuously and in four-course rotations including 1-year ‘renovation’ treatments in the form of (a) grazed ley, (b) ley cut for hay and grazed, (c) rape grazed, (d) mustard for green manure, (e) fallow.

Winter wheat, spring oats and spring barley were successive test crops common to all rotations and followed the ‘renovations’ or spring barley in the corresponding phase of the continuous cereals system. Main plot (rotation) comparisons were confounded with two levels of nitrogen fertilizer (0·2 and 0·4 cwt. N/acre) and three straw treatments (straw removed, burned or ploughed in) which were applied to all three cereal test crops.

All plots except those in fallow received 0·3 cwt. P2O5 and 0·3 cwt. K2O/acre every year. From 1945–48, leys, rape and mustard received 0·2cwt. fertilizer N/acre; from 1949 this dressing was doubled.

Grazing of leys and rape was by sheep.

2. In the earlier years the highest yields of wheat were obtained in the rotations containing rape, mustard or fallow, but in the later years yields after leys were superior to those in all other rotations. Wheat yields in the continuous cereals rotation soon declined and remained at the lowest level throughout, due largely to severe incidence of ‘take-all’ disease.

In the later years yields of barley and oats following 1-year ley were also superior to those in all other rotations.

3. In the six cropping rotations compared, all three cereal crops showed very marked responses to applied fertilizer nitrogen, particularly in the later years as the natural fertility of the site declined.

1. The distribution of calcium and magnesium in the contents of the reticulo-rumen sac, omasum, abomasum, small intestine, caecum and colon of the sheep was studied by means of ultrafiltration through collodion membranes.

2. In all organs except the abomasum considerable proportions of calcium and magnesium existed in a non-ultrafilterable form. In the abomasum where the pH is normally between 2 and 3 there was virtually no bound calcium or magnesium. The proportion of ultrafilterable calcium in the small intestine appeared to be dependent on the pH of the digesta, low pH values favouring higher proportions of ultrafilterable calcium. With magnesium this correlation was less obvious and appeared to be upset by unknown factors in the animals consuming a fresh grass diet.

3. From calculations it is postulated that the concentrations of ultrafilterable calcium and magnesium in rumen fluid are insufficient for these elements to be absorbed as freely diffusing ions, whereas in the abomasum and duodenum the concentrations of ultrafilterable calcium and magnesium are in favour of a net uptake from the gut.

A laboratory and pot-culture investigation to seek reasons for the variable response of grass and other crops to top-dressings of urea, and to the occasional phytotoxicity to seedlings of urea either mixed in the soil or drilled in contact with the seeds is described.

The part played by biuret, the chief impurity in commercial urea, has been examined. It can be phytotoxic to germinating seedlings when in contact, but in the quantities likely to be applied in agriculture in top-dressings, e.g. 150 lb. of urea with up to 2·5% of biuret, its effect is negligible. Up to at least 5% of biuret can be present in urea without affecting its ammonification or nitrification in soil.

It has been shown that loss of nitrogen to the atmosphere can account for the poorer responses of grassland to top-dressings of urea as compared with ‘Nitro-Chalk’ or ammonium sulphate.

The phytotoxic behaviour of pure urea to germinating seeds seems to be due to rapid production of ammonia. This gas is also evolved from topdressings of urea. Both the phytotoxicity and the loss to the atmosphere can be reduced by mixing urea with acid salts to neutralize the ammonia.

1. Dry-meal diets based on whitefish meal or soyabean oil meal, balanced in respect of minerals, and containing 28, 23 or 18% crude protein were given to pigs from 10 to 25 lb., and similar diets containing 18% crude protein were given from 25 to 40 lb. From 40 to 100 lb. and from 100 lb. to bacon weight all pigs were given the same diets with 16% crude protein and 14% crude protein, respectively.

2. From 10 to 25 lb. live weight the results showed that:

(a) With diets based on whitefish meal there was an improvement in growth rate of 11% (P < 0·05) and an improvement in feed conversion efficiency of 14% (P < 0·001) when the level of crude protein was increased from 18% to 23%. Growth rate and feed conversion efficiency were not improved further by increasing the level of crude protein from 23 to 28%.

(b) With diets based on soyabean oil meal, feed conversion efficiency and growth rate were not improved by increasing the protein in the diet from 18 to 23%, and performance was similar to that on the 18% protein diet based on whitefish meal. Pigs fed on the soyabean diet containing 28% protein were unthrifty and grew very slowly; some showed gastric ulceration.

(c) Consumption of the diets containing 18% crude protein was 8% higher (P < 0·05) than consumption of the other diets.

(d) Apparent digestibility of the dry matter of the diets, as measured by the chromic oxide marker method, rose as the pigs grew older, and apparent digestibility of the dry matter and crude protein of the diets based on soyabean oil meal was consistently lower than when whitefish meal was the main supplementary source of protein.

1. On cropping Agdell Experiment topsoils to exhaustion with perennial rye-grass in the glasshouse the total K uptakes were directly proportional to the initial exchangeable K contents of the soils.

2. The ability of the Agdell topsoils to release non-exchangeable K under glasshouse conditions decreased in the order: PK-rotation with fallow < NPK rotation with fallow < PK-rotation with clover < NPK-rotation with clover < no-fertilizerrotation with fallow = no-fertilizer rotation with clover.

3. Releases of non-exchangeable K were at least 2·5 times larger than the falls in the exchangeable K for all the Agdell soils.

4. In a ‘take-down’ experiment in the glasshouse on a soil receiving K fertilizer each year in the Saxmundham Rotation I Experiment, loosely held non-exchangeable K was released at a near-linear rate. At least a part of the loosely held non-exchangeable K in the Agdell soils was also released at a near-linear rate.