The results of about ninety field experiments carried out over three years to test dicalcium phosphate, nitrophosphate, ammoniated fertilizer and Gafsa rock phosphate are summarized and discussed. Soils with pH values of 6·5 and below are listed as ‘acid’, those with higher pH values as ‘neutral’. All comparisons were made in terms of fertilizers supplying the same total amounts of phosphorus.

Dicalcium phosphate dihydrate gave approximately the same yields as superphosphate for potatoes (both on acid and on neutral soils) and for grass, kale and barley. In one group of swede experiments mostly carried out in the north-east of the country dicalcium phosphate was inferior to superphosphate, but it was equal to superphosphate in another group of swede experiments, most of which were on acid soils in wetter areas.

A nitrophosphate made in England on pilot-plant scale was consistently inferior to superphosphate for barley, potatoes and swedes.

1. A crossing experiment was carried out between two breeds of sheep: the Wiltshire Horn—a breed with a short-stapled fleece which is normally shed both in lambs and adults, and the Scottish Blackface—which has a long-stapled carpet type of fleece. Animals of F1, F2 and both backcross generations were studied for gross characteristics of the fleece.

2. The influence of the Wiltshire genotype caused a high incidence of fleece-shedding animals amongst all the crosses. Three separate components of the shedding process were distinguished: (a) the ability to shed, (b) the extent of shedding—or proportion of the body area denuded, (c) the time of onset of shedding. Attributes (a) and (b) were determined genetically; control was probably on a multifactorial basis, although there may have been fewer genes involved than for the other characters studied. Given the genetically determined existence of (a) and (b), (c) was apparently controlled by the environment. Seasonal change in day length was postulated as a major operative factor.

3. The mid-side staple length of Wiltshire crosses was less than that of the Blackface parents. The decrease resulted partly from shedding and partly also from a reduction in the average growth rate of some fibres. When corrected for shedding the mean staple lengths of the crosses were about equal to the values theoretically expected on the basis of multifactorial inheritance without directional dominance.

4. The mean fleece weight of the Wiltshire crosses was less than that of the Blackface parents, due, about equally, to: (a) loss of wool by fleece shedding, (b) reduced wool production—probably caused, at least partly, by the decreased average growth rate of some of the component fibres of the fleece. Differences in wool production appeared to be inherited multifaetorially.

Thirty-six Hereford dwarfs, ‘comprest’, dwarf-like, and eight controls were available. Body and skin measurements were taken and the types of head abnormalities and cardiovascular activities were recorded. Haematological tests and chemical analysis of blood and hair were carried out.

Typical dwarfs showed characteristic head abnormalities with varying degrees either at birth or later in life, possibly as a result of different stages of development at which the defective gene(s) comes into operation. There were progressive changes (qualitative and quantitative) in the expression of dwarf characteristics. Typical dwarfs were chronic bloaters, with pot-shaped belly or with normal belly. Atypical dwarfs were either stunted, showing (miscellaneous) deleterious genes or ‘comprest’ types. The daily live-weight gain of typical dwarfs ranged from 0·71 to 1·69 with an average of 1·26 lb. (controls 1·72 lb.). Body, head, and limb indices in typical dwarfs are similar to those of the ‘comprest’ and the control animals at comparable weights. Volume index was higher in the control than in the typical dwarfs. In the bloater dwarfs the width of the body at the shoulder region was considerably narrower. Skins of the typical dwarfs were thinner. The bloater dwarfs showed a diurnal bloat cycle (in relation to feeding time) as judged by body circumference. The severity of bloat was irregular.

There was no significant difference between typical dwarfs and control animals in rectal temperature, pulse rate, blood, specific gravity, prothrombin time, sedimentation rate, red cell count, electrophoretic pattern of serum proteins, serum creatine and creatinine and calcium/phosphorus ratio in hair samples. Typical dwarfs had slower respiration rate, lower blood haemoglobin, haematocrit, and white blood count than did the controls. Post-mortem examination of dwarfs did not show similar causes of death in each case. The heart of the dwarfs was spheroid, showing severe dilation in most cases.

1. Both sides of sixty-eight carcasses of Aberdeen-Angus cross steers and heifers were broken down into wholesale joints by the same butcher using a modification of the London and Home Counties style of cutting. Thirty-four of the cattle were fattened on grass in the summer of 1955 and the other thirty-four in yards during the following winter.

2. Sides of steer carcasses averaged some 50–60 lb. heavier than those of heifers both in summer and winter, and the yard-fattened cattle gave sides averaging 10–20 lb. heavier than those from grassfattened cattle.

3. The cuts along the underline of the animals (brisket and flanks) were increasing in weight at proportionally the greatest rate and the shin and hind-leg cuts at about half this rate, with those along the top of the back intermediate.

4. At a side weight of 300 lb., steers were significantly lighter than heifers in the weight of kidney knob, cod fat, thin flank, forequarter flank, loin and rump, whereas they were significantly heavier than heifers in weight of leg, shin, topside, top rump and the neck cuts (clod and sticking). These differences suggested that at this weight of side, heifers were at a more advanced stage of development than steers.

1. The sources of calves for rearing for beef are discussed and the dependence of the beef industry upon the dairy industry demonstrated.

2. An experiment designed to compare the effects of four levels of feeding on the growth rate, conformation, economy of food conversion and type of carcase produced, of three breeds of spring-born steers, Hereford, Dairy Shorthorn and Friesian, is described. The levels of feeding are high or moderate in the calf stage, each followed by high or moderate feeding in subsequent winters.

3. The results on growth and time of fattening are given and discussed.

4. The calves fed on a high level were almost twice the weight of those fed on a moderate level at 8 months old.

5. The well-reared calf had an advantage over the moderately reared calf for the rest of its life.

6. Although calves which had been reared moderately showed a marked improvement in growth rate when subsequently fed on a higher level they did not reach the weight of calves fed well throughout at 2 years old.

7. The level of feeding in the calf stage had little effect upon the time of fattening provided that the level of feeding in the winter periods of subsequent life was on a high level.

8. When subsequent feeding was on a moderate level in the winter months, the calf reared well initially fattened on grass a year earlier than the moderately reared animal.

9. The high-moderate treatment is shown to be the most satisfactory from many points of view. On this treatment a minimum of concentrates is used in the production of beef.

10. The moderate-moderate cattle may be too heavy for present-day requirements when finished off grass at 3½ years old.

11. Cattle which were fed on a high level in winter from 8 to 14 months put on less live weight in the following summer than those fed moderately. A live-weight gain of about 1 lb. a day in winter would appear to be satisfactory if the cattle are to make good use of grass in the following summer.

12. These main feeding treatment effects applied to the three breeds used.

13. The Friesians were heavier than Dairy Shorthorns or Herefords as calves, and the live weight at most ages was in descending order Friesians, Dairy Shorthorns, Herefords.

14. The growth rate of Friesian steers was higher than that of the other two breeds at most stages of life, but the difference between Dairy Shorthorns and Herefords was negligible.

15. The Herefords finished earlier than the Dairy Shorthorns and Friesians when fattened in yards or on grass.

16. There was some indication (Brookes, 1954) that husk and ringworm caused less trouble with cattle which had been well reared than with those moderately reared.

1. The problem of inbreeding and the fixation of apparent heterosis in the cultivated tomato and in inbreeding crop species generally is discussed. The case is argued that ‘heterosis’ as normally understood in out-breeders is not likely to exist as a general phenomenon in inbreeding species.

2. Selections were made among segregating progenies of two successful, commercial F1 hybrids, and the performance of the selected lines, up to the F4 generation, shows that the superiority of the hybrids over their parents can be fixed in purebreeding lines.

3. Owing to selection effects in inbreeding species of crops the best parents will differ in respect of fewer quantitative loci than is to be expected from general experiments on quantitative inheritance. In the present material, desirable recombinants were isolated at a frequency of 1 in every 1000–1500 F2 individuals.

4. The utility of F1 hybrids in the tomato thus depends on the economy of effort involved in their development as compared with the isolation of pure lines. It is concluded that the production of hybrids is to be favoured only when reliable methods of prediction of their performance are available, and then as an interim measure while pure-line forms become available.

1. The availability of iron in five species of legumes has been investigated, using the rat as the experimental animal.

2. Two procedures were employed, namely, the increase in blood haemoglobin concentration, and the gain in total grams of haemoglobin, by nutritionally anaemic rats.

3. Inorganic iron, as ferric chloride, was shown to be significantly more available than the iron contained in the five legumes.

4. A significant difference in iron availability between alsike and wild white clover was obtained with both methods of expressing the results. Differences between other species were not significant.

5. The data are compared with those obtained for three species of grass in an identical experiment reported previously.

1. Three winter feeding experiments (1954–57) were carried out using small flocks of Border Leicester x Cheviot ewes tupped by a Suffolk ram.

2. The feeds used were various combinations of (a) silage, (b) hay, (c) ‘winter grass’, and (d)concentrates. Their value in late pregnancy was compared in terms of performance of the ewe and the birth weight of the lambs.

3. In addition, in one year (1956–57) the effect of level of nutrition in early pregnancy and during the first 28 days of lactation was studied.

4. It was found that ‘winter grass’ could replace silage and hay where a concentrate ration was being fed.

5. Satisfactory results were obtained with a concentrate ration of ⅜ lb. per head per day rising to ¾ lb. per head per day by lambing time.

6. In the mild winter of 1956–57 a group of ewes produced normal healthy lambs when fed entirely on ‘winter grass’ during the latter half of pregnancy.

7. The intensity of grazing of the ewes in early pregnancy affected their live-weight gain, but this seemed to have little effect on lamb production.

8. A high plane of nutrition during early lactation resulted in a significantly greater live-weight gain of lambs over this period. The difference had been reduced to a non-significant level by mid-June.

9. None of the treatments imposed had any very marked effect on the nematode egg-output of the ewes.

It was shown in previous work (Evans, 1958) that a cereal diet supplemented with 7% of white-fish meal supplied around 0·76% of lysine and 0·5% of methionine plus cystine. The addition of more pure l-lysine monochloride or dl -methionine to this animal-protein diet failed to bring about any significant improvement in the rate of growth, efficiency of food conversion or in the nitrogen retention of the pig, in the critical period between weaning and 80 lb. live weight. When the same cereal diet was supplemented by as much as 20% of ex. dec. ground-nut meal, however, the lysine content amounted to only 0·62% but the methionine plus cystine was 0·53%. On adding 0·2% l-lysine plus 0·2% dl-methionine to the 20% ground-nut diet the utilization of the nitrogen in the food was improved and the excretion of nitrogen in the urine was reduced. This finding was confirmed by means of a statistically designed growth trial, the daily rate of live-weight gain, improving from a mean value of 0·86 to 0·98 lb. following the addition of 0·2% of lysine and methionine, respectively, to the diet, the corresponding saving in meal consumption, between 35 and 80 lb. live weight, amounting to 16 lb. One group of ten pigs received a supplement of 0·2% of methionine only, and since it failed to show any improvement in performance over the control group it was concluded that 0·5% of methionine plus cystine must suffice to support satisfactory growth.

A split-sample experiment involving 14,319 first inseminations was carried out at sixteen artificial insemination centres to compare the fertility of semen diluted with skim-milk and skim-milk containing 10% glycerol when used on the first, second, third and fourth days after the day of collections.

The addition of glycerol to the heat-treated skimmilk diluent significantly reduced the decline in fertility with increasing age. However, there were indications that glycerolization also reduced initial fertility.

The relationship between cortical area and fibre area has been examined in the N/N, N/ +, + / +, + /nr and nr/nr genotypes of the New Zealand Romney, using skin biopsies taken at birth, 1, 3 and 16 months of age. The presence of the nr gene was shown to reduce significantly the relative cortical area. Within the genotypes there was an increase in relative cortical area with increasing age and in two-tooth ewes of N/N and N/ + there was an increase in relative cortical area in winter compared to summer.

Fibre growth rates in length for primaries and for prenatal and post-natal secondaries were found for lambs between 1 and 3 months and for 16-monthold ewes. In N/N, N/+ and nr/nr primary fibre growth tended to be increased and post-natal secondary fibre growth tended to be decreased relative to + / + values.

In both cortical area and fibre growth rate the greatest genotypic effect was shown by the primary fibres.

Some estimates of cortical volume have been made by combining the information on cortical area and fibre growth rate and the relationship of these factors to follicle density and mean fibre area has been discussed. Finally, an indication has been given of how the associations of all these four factors might be usefully examined in some British breeds.

1. The red cells of sheep's blood containing a high concentration of potassium were found to have a higher dry-matter content and specific gravity than the red cells of sheep's blood with a low potassium content.

2. While the diet and age of the animal affected the dry-matter content and specific gravity of the plasma, they did not have a noticeable effect on the results obtained for the red blood cells.

3. Breed influenced the measurements for both the red blood cell and plasma.

4. In the three breeds of sheep examined an inverse relationship existed between the dry matter content of the red blood cells and of the plasma.

5. There is evidence that a correlation exists between the haemoglobin type of animal and the dry-matter content and specific gravity of the red blood cells.

1. Field studies on Impatient parviflora DC. in shaded situations indicated the need for experimental investigation of the effects on growth of varying single factors of the aerial environment in otherwise constant conditions.

2. The use of cabinets which allow accurate control of the aerial environment for studies in physiology, morphogenesis, pathology and plant selection is discussed.

3. By comparison of the development and assimilatory ability of the leaves of I. parviflora, it is shown that plants may be grown in wholly artificial conditions which are substantially identical with those grown under comparable conditions out of doors.

The experiment with two trials was carried out to determine the effect of low and high germination and three seed rates of lucerne on the establishment, mortality, and yield of fodder on heavy soil at Cambridge during 1955–8.

Highly significant differences were obtained between seed rates and germinations in the number of plants established in the year of sowing. The highest number of plants with thin and short tap roots were in a dense crop at 15 lb./acre and 83% of them were unable to survive the first winter. The highest mortality occurred between sowing and the first harvest year, and the heaviest loss of plants was in the lucerne drilled at 15 lb./acre and lowest at 5 lb./acre. Interaction between germination and seed rates was significant at 1% level in the first and at 5% level in the second count only.

The highest differences in yield results were in the first harvest year, when a significantly lower yield was obtained at 5 lb./acre than at 10 or 15 lb./acre, but there was no significant difference in yield between 10 and 15 lb./acre. Lucerne with a high germination at all seed rates gave significantly higher yields than lucerne with a low germination in both trials.

1. An experiment was carried out to determine the effect of L-thyroxine implantation upon the wool production and live-weight change of Corriedale and Suffolk × Border Leicester-Merino sheep.

2. Groups fed hay in restricted amounts gave approximately 12% more wool when treated with thyroxine. Since there was no change in fibre diameter, this was presumably due to an increase in staple length.

3. Groups fed hay ad lib. gave no significant increase in wool production when treated with thyroxine, nor did their rate of food consumption alter. Their level of wool production over the 5-month period was approximately the same as that of the thyroxine treated, restricted fed, sheep.

4. All thyroxine-treated groups lost approximately 10% of their live weight. This was in the nature of a steady decrease from the second to the seventh week after treatment. Live weights then remained at about the same level for a further 8–10 weeks when they commenced to return gradually to their original weights.

In Exp. 1 groups of piglets weaned at about 9 lb. live weight were fed one of three 29% protein diets up to 26 lb. live weight. These diets A, B and C contained 42, 20 and 0% dried skim milk, 15, 25 and 32% white fish meal and 22, 34 and 47% rolled oat groats, respectively. At 26 lb. all pigs were changed over to a standard 17% protein diet.

The replacement of about one-half of the dried skim milk in diet A with white fish meal and rolled oat groats caused 4% faster growth from 9 to 26 lb. live weight, but the replacement of all the dried skim milk caused growth over the same weight range to be slower by 6%. The quadratic component of these treatment effects was significant at P < 0·0·25. The slower growth with the diet containing no dried skim milk was associated with a lower daily consumption of feed, and the improved growth rate with the intermediate skim milk level was probably associated with an improvement in food conversion efficiency. Treatment differences in food conversion efficiency before 26 lb. live weight, however, were not statistically significant. There were no significant carry-over effects of treatments upon performance from 26 to 50 lb. live weight.

In Exp. 2 piglets weaned at about 9 lb. live weight were fed individually up to 40 lb. live weight. From 9 to 26 lb. antibiotic levels of 22, 45, 67 and 90 mg./lb. feed were compared, but from 26 to 40 lb. all pigs were fed a standard diet containing 18 mg. antibiotic/lb. In diets fed before 26 lb. the antibiotic was a mixture of 3 parts by weight chlortetracycline: 1 part by weight procaine penicillin. From 26 to 40 lb. live weight the antibiotic fed was chlortetracycline.

Before 26 lb. live weight increases in antibiotic level caused average increases of up to 5% in growth rate and 4% in food conversion efficiency. Taken in conjunction with previous results the improvement in growth rate in favour of the highest antibiotic level was significant at P < 0·05.

There were no carry-over effects of antibiotic level on growth rate from 26 to 40 lb., but there was the suggestion of a linear trend whereby each increase in antibiotic level fed before 26 lb. caused a decrease in food conversion efficiency between 26 and 401b. (P = 0·10).

The results are discussed in relation to financial economies which may be made in diets for early weaned pigs.

It has been established that the mineral deficiencies can be rectified on both the fescue dominant and Molinia dominant swards of mid-Wales without recourse to ploughing and reseeding (Milton & Davies, 1947). The processes adopted consisted either of liming the native swards in the absence of fertilizers or else fertilizing the sward either in the presence or absence of lime. The grazing animal played an important part in the changes that took place. Some of the treatments resulted in the partial or complete extinction of the native hill herbage and its replacement by grasses and clovers of high productivity and mineral content.

1. Dry-meal diets for pigs weaned at 6–7 lb. mean live weight and 6·9 days mean age were supplemented with antibiotic, pepsin and an α-amylase preparation according to a factorial design involving sixty-four pigs on eight treatments. Antibiotic was included in the respective diets from weaning to 40 lb. live weight and the enzymes from weaning to 25 lb. live weight.

2. Antibiotic supplementation gave a 12·5% increase in rate of growth from weaning to 40 lb. P < 0·001) by reducing the incidence of scour and increasing food consumption from weaning to 25 lb. Antibiotic exerted no effect upon efficiency of food conversion.

3. Pepsin supplementation increased the incidence of scour and reduced rate of growth by 3·7% whilst being fed (P < 0·1) and by 8·6% after it was omitted at 25 lb. live weight (P < 0·01). Efficiency of food conversion was reduced by 5·5% when pepsin was fed (P < 0·05) and by 4·6% after it was omitted at 25 lb. live weight (P < 0·1).

4. α-Amylase appeared to exert little influence upon either growth rate or efficiency of food conversion except in the presence of pepsin. It appeared to counteract the harmful effects of pepsin on growth rate from weaning to 25 lb. and on food conversion efficiency from 25 to 40 lb. This resulted in a 5·5% increase in growth rate during the first period (P < 0·01) and 5·7% improvement in food conversion efficiency during the second period (P < 0·05).

5. The overall effects of antibiotic, pepsin and α-amylase supplementation upon time taken to reach 40 lb. live weight were a reduction of 5·6 days, an increase of 3·8 days and a reduction of 3·9 days, respectively.

1. Twelve lambs varying in age from 5 to 35 days in age were slaughtered and their carbohydrate-digesting enzymes studied for any change in activity with increase in age.

2. Results are given for the changes in weight of different parts of the digestive organs and their contents, and for the content of NaCl and of total acidity in the abomasum contents.

3. Pancreatic and small intestine amylase showed only a slight increase in activity up to 5 weeks of age.

4. Lactase and maltase activity in the small intestine were almost constant from 1 week to 5 weeks of age.

5. No sucrase activity was measurable in any of the lambs slaughtered in either the small intestine wall or its contents.

6. A comparison was made between the carbohydrase activity of the young pig and the lamb.

7. Calculations based on the enzyme activities of the tissues showed the theoretical amounts of different carbohydrates which can be digested by lambs and young pigs of varying age groups.

8. The results suggest that the young lamb is dependent on the early development of its rumen fauna and flora for the utilization of all other carbohydrates except lactose and glucose.

The experiment involved nine litters, each containing four male and female pairs of pigs. At about 10 days of age the four pairs within each litter were randomized one to each of the following treatments. (1) Pigs left with their dams, weaned at 56 days old and then fed ad lib. until they each weighed 50 lb. (2) Pigs weaned at 10 days old and fed ad lib. until they each weighed 50 lb. (3) Pigs weaned at 10 days old, given restricted feed allowances so that they weighed 30 lb. at 56 days old, then fed ad lib. until they each weighed 50 lb. (4) Pigs weaned at 10 days old and given restricted feed allowances so that they weighed 30 lb. at 56 days old and 50 lb. at 90 days old. Between 50 lb. and slaughter at 205 lb. all pigs were kept to the same very high plane of feeding, which was based on live weight. All pigs were individually fed from weaning onwards.