Some published figures relating to the incidence of swarming have been examined, and records obtained in the routine examinations of colonies in honeyproducing apiaries have been analysed. It is concluded that in these apiaries between 10 and 40% of colonies would swarm in an average year, if they were given excess hive space and otherwise left alone. The proportion of colonies which produced queen cells varied from year to year and from one apiary site to another. This variation was presumably due to environmental factors, but it was substantially independent of those factors which determined honey yield. There was no evidence that it was due to the effects of conditions in the years when the queens were reared. After the end of June, at least, the tendency for colonies to produce queen cells was markedly less with queens of the current year than with queens of the previous year, and was probably also less with queens of the previous year than with still older queens. Queen cells were most frequently observed in colonies in the latter half of May and in June and July. The mean time of queen-cell production varied from year to year. Many colonies which began to rear queens eventually ceased to do so with no other treatment than removal of queen cells. Queen rearing did not begin and end in all colonies at the same time; many colonies began rearing queens after others had stopped.

1. With steers of indigenous cattle, the supplementation of veld grazing with two levels of salt with and without protein in the dry season has been investigated.

2. The feeding of 1 oz. of salt speeded up growth to a strongly significant degree, but under the experimental conditions no benefit was obtained during the dry season from adding a protein supplement to the salt. Protein supplementation without salt produced no significant effects upon growth.

3. The addition of 2 oz. of supplementary salt was found to give some increase in growth when compared with the control, but appeared to exert an inhibitory action as compared with the lower salt level, and again there was no benefit gained from the addition of a protein supplement in the dry season. No reason can yet be given for this.

4. Additional evidence has been given to support the suggestion that the tropical indigenous animal possesses the capacity to stop growing during adverse nutritional conditions.

An investigation has been undertaken to study the apocrine gland population of the skin of the three indigenous breeds of cattle native to Northern Rhodesia, and a comparison made between them and the Africander.

It was found that the Angoni had the greatest density of glands/sq.cm. and that this density agreed closely with mean figures quoted for Bos indicus. The Barotse and the Tonga, both Sanga types, had significantly lower gland density, but were both significantly greater than the Africander which is a relict Zebu form.

Dowling's finding that the decrease in the density of the glands with age is due to the ‘spread’ of the constant number laid down at birth by the growth of the skin was confirmed.

A very close correlation between the density of the apocrine glands and the heat toleration coefficient was established.

From a consideration of previous work, it is concluded that the density of the apocrine gland population is only one of the factors concerned in the control of thermo-neutrality by cattle; in this there is some disagreement with the conclusions reached by Australian workers.

Groups of pigs were weaned at 8, 14 and 20 lb. live weight from each of seven litters. Each of the twenty-one groups was housed separately and selffed a 30% protein diet ‘A’ up to 25 lb. live weight.

From then until 56 days of age each group was selffed a 22% protein diet ‘B’.

Weight at weaning had no significant effect on age at 40 lb. live weight, but weights at 56 day old of 46·5, 50·2 and 47·7 lb. for pigs weaned at 8, 14 and 20 lb. respectively tended to favour weaning at 14 lb. (P < 0·10).

Pigs weaned at 8, 14 and 20 lb. each required 25, 16 and 6 lb. respectively of expensive diet ‘A’ to reach 25 lb. live weight. To grow from 25 to 40 lb. live weight they each required 30, 28 and 27 lb. of diet B, and this trend in favour of the pigs weaned at heavier weights was significant at P < 0·05.

These results are discussed in relation to the system of early weaning.

1. The main experiment described was a 4 × 2 factorial designed to test levels of 18, 21, 25 and 28% crude protein in diets fed from 25–50 lb. live weight and to compare an all-vegetable diet with one containing white fish meal for pigs of 50–100 lb. live weight.

Forty-eight pigs were used in the experiment. They were weaned at an average weight of 9 lb. and were fed a standard 29% protein diet until they each weighed 25 lb. Between 100 lb. and slaughter at 200 lb. they were fed a standard all-vegetable diet containing 14% protein.

Live weights and food-consumption figures for each pig were recorded throughout the experiment and carcass-quality measurements were taken.

2. Forpigs of 25–50 lb. there was no advantage in raising the level of crude protein above 18% in a diet based on white fish meal, dried skim milk, rolled oat groats, ground barley and fine millers' offals. Level of protein fed during this stage of the experiment did not affect performance at any subsequent stage, nor did it affect carcass quality.

3. For pigs of 50–100 lb. rates of live-weight increase and food-conversion efficiency were poorer by 13 and 14%, respectively, on an all-vegetable diet containing 17% crude protein than on a diet including 7·5% white fish meal and containing 15% crude protein. This difference was not affected by level of protein fed before 50 lb., and in its turn it did not affect either growth performance from 100–200 lb. or carcass quality measurements.

4. The following notes relate to the overall performance of early weaned pigs during this experiment: After being weaned at an average of 9 lb. when 10 days old, the pigs reached 25 lb. at 36 days old and 50 lb. at 58 days old. They each ate an average of 29 lb. of the 29% protein diet 1A and 59 lb. of the diets 2 A–D fed from 25–50 lb. Between 50 and 200 lb. food-conversion efficiencies were lower than is usual for individually fed pigs at the Rowett Institute, but rates of live-weight increase were satisfactory when considered in relation to the plane of feeding followed, and the average age at 200 lb. was 185 days. Of the carcasses 85% graded A.

5. In a pilot trial pigs were changed over from the 29% protein diet 1A to the 18% protein diet 2D at 13, 17, 21 or 25 lb. live weight.

There was a linear trend towards slower rates of live-weight increase as the weight at change-over was reduced, and pigs changed at 13 lb. took 7 days longer than those changed at 25 lb. to reach 40 lb. live weight. Overall food-conversion efficiency was best when the change was made at 25 lb., but because of the high cost of diet 1 A in relation to diet 2 D there was a linear trend for the total cost of food per pig to be lower as the weight at change-over was reduced.

6. The results of the pilot trial were discussed in relation to the effects on the lightest pigs in a group of changing to diet 2 D as the average weight per pig reached 25 lb.

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 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. 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.

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.

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.

1. An in vitro method is described whereby it is possible to obtain the digestibility coefficient of silage cellulose. The apparatus and techniques used are described in detail and the reproducibility of the results obtainable is stressed.

2. The results so obtained on twenty-seven samples of silage of diverse nature, with regard to composition and method of production, show a reasonable degree of correlation with the corresponding figures for the digestibility coefficients of crude fibre obtained by feeding trial.