1. Groups of colonies have been moved to crops requiring pollination: group A, before any blossom appeared; group B, when 5–15% of the crop was in flower; and group C, when the crop was in full flower, and the amount which the colonies of the different groups visited the crop was determined. The results tend to show that colonies of group B visited the experimental crop more than colonies of group A, thus supporting recommendations that colonies should not be moved to a crop requiring pollination until it has started to flower, so that the bees will not have previously become conditioned to visiting other flower species in the locality.

2. When a colony is moved to a new site its foragers tend to visit species they have visited previously, and the amount of a particular pollen that a colony collects at a new site is sometimes related to the amount of it the colony collected before it was moved.

3. The conclusion of previous workers that different colonies utilize the local flora in different ways have been confirmed. Different colonies vary greatly both in the number and kind of species they visit and in the extent to which they visit the same species. Although the extent to which colonies visit certain species tends to be related to the extent they have visited them previously, exceptions often occur.

1. Twelve experiments were carried out in Bedfordshire and Hertfordshire in 1955–57 to compare combine-drilling and broadcasting muriate of potash for barley. Ordinary mineral soils were used and only one contained more than 25% of calcium carbonate.

2. On average of all the experiments in each year 0·25 cwt. K2O/acre drilled with the seed gave higher yields than 0·5 cwt. K2O/acre broadcast and worked into the seedbed. The average extra yields of barley from combine-drilling, as compared with broadcasting, were 1·2 cwt./acre when 0·25 cwt. K2O/acre was applied and 2·0 cwt./acre of grain when twice as much K2O was given. In twenty-one of the total of twenty-four comparisons drilling gave higher yields than broadcasting and in onethird of these comparisons the effects were significant. Combine-drilling gave higher average yields of straw than broadcasting.

3. The average level of response was not great, the low and high rates of combine-drilled muriate of potash increasing yields by 13 and 16%, respectively. Only a small proportion of the applied potassium was taken up by the crops; apparent recoveries by grain plus straw averaged 11% of the light-drilled dressing and 8% of the heavy dressing.

4. The level of response to potassium varied from year to year, but was much greater on average in the 1955 experiments than in 1956 and 1957. There was no close relationship between the degree of response and values for dilute hydrochloric-acidsoluble potassium or exchangeable potassium in the soils used.

Eleven winter wheat experiments were carried out from 1955–57, to compare the effects of nitrogen on three stiff-strawed varieties of winter wheat, Heine 7, Hybrid 46 and Minister. In 1955 the experiments tested ‘Nitro-Chalk’ top-dressings at rates supplying 0·45, 0·90 and 1·35 cwt. N/acre. In addition, drilled dressings supplying 0·15 cwt. N/acre were supplemented with either 0·30 or 0·75 cwt. N/acre as a top-dressing.

In the 1956 and 1957 experiments ‘Nitro-Chalk’ top-dressings were applied at 0·60 and 1·20 cwt. N/acre. In addition, divided dressings were compared by supplementing 0·15 cwt. N/acre by combine-drill with 0·45 cwt. N top-dressing.

Significant increases in yield were obtained from the first increment of nitrogen in twenty-three of the thirty-three available comparisons. There were significant additional gains from the second increment of nitrogen in only seven of the same comparisons. Responses to nitrogen varied considerably between seasons. Large and consistent responses were obtained at all centres in 1955 and dressings supplying 0·9 cwt. N/acre were well worthwhile. In 1956 responses were generally smaller and dressings in excess of 0·6 cwt. N/acre could only be justified at two centres. Mean responses in 1957 were lower than those obtained in either of the previous season and 0·6 cwt. N/acre was sufficient for maximum yields at three of the four centres.

There was little advantage in dividing dressings of nitrogen between autumn and spring in any of the experiments and none of the differences reached significance. On average, higher yields were obtained by retaining the whole of the nitrogen until the spring, than by applying part of the dressing in autumn by combine-drill.

Comparisons between the varieties show that Hybrid 46 was the only variety which was able to take consistent advantage of the heaviest rates of manuring. In each year Hybrid 46 produced the highest percentage increase in yield and Minister the lowest. In addition Hybrid 46 contained the highest percentage of nitrogen in the grain when averaged over each level of manuring. The percentage recovery of nitrogen was calculated for each year and each variety. Comparisons of this data show that Hybrid 46 converted more of the fertilizer nitrogen into grain or crude protein than either of the other two varieties. The experiments provide evidence that there are considerable variations in the efficiency with which present-day winter wheat varieties can utilize nitrogen, and that varieties with both high fertilizer efficiency and high unmanured yields are likely to increase the level of crop production.

1. The influence of frequency of cutting on the yield and chemical composition of Pennisetum purpureum Schum under the environmental conditions obtaining in south-western Nigeria was studied in 1953–54. The cutting frequencies adopted being seventeen, eight, six and four times sampling a year, which permitted the plants to grow for intervals of 3, 6, 8 and 12 weeks, respectively, before cutting.

2. When elephant grass was sampled four times a year, at an interval of 12 weeks, a yield of 52·9 tons of green fodder per acre was obtained for the 11-month period (24 June 1953 to 27 May 1954). This yield was 1·8 times more than the green fodder produced from plots sampled seventeen times a year, at 3-weekly intervals, and 1-4 times more than that obtained from each of those sampled six times a year (intervals of 8-weeks) and eight times a year (6-weekly intervals), respectively. These yields, which are probably the highest ever recorded for any grass species grown in unfertilized soils in Nigeria, are also higher than the yields reported under similar conditions and treatments in other tropical countries.

3. The percentage dry matter similarly increased with the length of cutting intervals. Differences in yields of dry matter between the various treatments are more pronounced than similar differences for green fodder yields. The dry-matter yields obtained from either the 6-weekly or the 8-weekly cutting intervals were significantly higher than those obtained from the 3-weekly cut samples, while those from the 12-weekly cut samples were significantly superior to each of the other cutting treatments. The difference in yield between the 8- and the 6-weekly cut samples, however, was not statistically significant.

4. A progressive reduction in yields of dry matter and of green fodder was shown with successive cuttings, particularly in the case of the more frequently cut grasses; the yields obtained during the 1964 seasons were lower than those of 1953. It is possible that the application of fertilizers might arrest this diminution in growth and yield.

5. It was shown that when the grass was allowed to grow for a period longer than 3 weeks, the stems of Pennisetum purpureum Schum tend to mature more rapidly than the leaves. This fact might be responsible for the rapid deterioration in nutrient content, so characteristic of tropical fodders.

6. The percentage crude protein and of silicafree ash fell as cutting intervals increased; the percentage dry matter, crude fibre and nitrogenfree extract rose directly with length of cutting intervals. It was shown that it is best to cut elephant grass every 3 weeks of growth in order to obtain the highest yield of protein and of silicafree ash per acre; this grass should, however, be cut every 12 weeks to obtain the maximum yield of total nutrients and carbohydrates. It does not appear profitable to cut or graze elephant grass at 6- or 8-weekly intervals for either of the above purposes.

7. While green fodder yields were directly, drymatter yields were inversely, related to the degree of monthly precipitation. Generally, periods of high rainfall were followed by high yields of green fodder and low yields of dry matter, those of low rainfall by low green fodder and high dry-matter yields. The percentage crude protein and of silicafree ash of dry matter, fluctuated directly with rainfall; the percentage nitrogen-free extract and of crude fibre showed an inverse relationship with rainfall fluctuations.

It is these latter constituents rather than the former which thus reflect the dry-matter content of the herbage.

1. Changes are observed in the concentrations of a wide range of substances found in blood and rumen contents when sheep are first turned out to lush spring grass.

2. With some metabolites (e.g. rumen α-amino nitrogen, blood VFA) the increase is only temporary, and the animal (or its rumen microbial population) quickly adapts to the changed conditions. With other metabolites (e.g. rumen VFA) there is a sustained increase over a period of at least three weeks on grass.

3. It is possible that the nature of the previous diet may determine the magnitude of the metabolic changes occurring.

4. The overall nature of these changes should be taken into account in assessing the aetiology of the metabolic diseases occurring in ruminants under similar conditions.

1. Acid-base changes were observed in the blood of some sheep after turning them out to lush spring grass.

2. These changes were observed in animals previously fed a diet of hay plus concentrates. No changes were found in animals previously fed hay alone.

3. Reasons are given for believing the acidosis observed was a consequence of feeding on lush pasture, and not a consequence of the exercise and excitement involved in rounding up sheep for sampling.

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. 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. 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.

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.

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.

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.

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.