The ‘built-up or deep’ litter system for housing poultry came into use in America during World War II, when labour and materials were restricted. It consists of recently used Utter, at least 6 in. in depth, containing micro-organisms which produce beneficial heating, synthesizing and sanitizing effects (Halbrook, Winter & Sutton, 1951; Kennard & Chamberlain, 1951). Four requirements have been laid down by Bott, Ferguson, Berkland & Winter (1952) for proper functioning of deep litter; they are:

(1) The depth of the litter must be greater than 6 in. to ensure the absorption of fresh dropping and for effective chemical and biological activities.

1. A co-ordinated trial has been carried out at 17 centres to compare the effects on performance and carcass quality of feeding growing pigs once or twice daily.

2. No significant differences were found between growth rate, efficiency of food conversion or length of pigs on the two treatments.

3. Killing out percentage was on average 0·92% worse for the pigs fed once daily, a significant effect, probably because the pigs on the two treatments received different amounts of food at the last feed before slaughter.

… In short, he used many learned arguments to persuade his audience out of their senses; and from stench made a transition to filth, which he affirmed was also a mistaken idea, in as much as objects so called, were no other than certain modifications of matter, consisting of the same principles that enter into the composition of all created essences, whatever they may be: that in the filthiest production of nature a philosopher considered nothing but the earth, water, salt and air of which it was compounded.…

1. In the winters of 1959–61 three randomized block experiments were carried out to study protein requirements of heifers of 800–1000 lb. live weight. 24 animals were used in each experiment. Half the animals were kept indoors; the remainder stayed out of doors except for 1 hr. per day when they came into covered yards to receive their concenrates ration.

2. Rations were based on straw, cereals and roots. The intake of crude protein was varied by replacing cereals by decorticated ground nut meal. The estimated level of energy intake varied from 7·2–8·2 lb. starch equivalent/day between experiments, but the level was constant for all treatments within an experiment.

3. At the end of each feeding trial the nitrogen balance was measured for 2 animals from each treatment. The results confirmed the estimated levels of digestible crude protein intakes upon which the experiments were based.

4. An increase in intake of digestible crude protein (as determined in the metabolism trials) from 0·35 lb./day to 0·72 lb./day gave a marked response of 0·45 lb./day in the rate of live-weight gain. Further increases in protein intake gave little response in live-weight gain. It was concluded that for heifers of 800–900 lb. live weight the protein requirement for maintenance and a live-weight gain of 1·2 lb./day was 0·70 lb. digestible crude protein/day.

5. Comparison of the estimated starch equivalent intakes in the three experiments showed that in heifers receiving 0·52 lb. digestible crude protein per day the rate of gain increased from 0·25 to 0·90 lb./day as the level of energy intake increased from 0·78 lb. starch equivalent/100 lb. live weight per day to 1·01 lb./100 lb. live weight.

6. Biological value of the dietary nitrogen decreased as level of protein intake increased. The values for individual animals ranged from 61·3 to 82·4. The mean value was 69·5.

7. The weather during these experiments was typical of winters in south-east England with mean minimum ground temperatures about 30° F. and mean maximum and minimum air temperatures of about 50° F. and 35° F., respectively. Snow fell occasionally only; 3½–5½ in. of rain fell in the period 1 January to 31 March. In 2 years out of 3 the outdoor group grew slightly faster than the indoor groups. In the third year this trend was reversed.

The L-threonine requirement of the weanling pig is 0·45% of the air-dry food. This level supports as good growth and economy of food conversion and promotes as good retention of nitrogen as higher amounts.

It is unlikely, when pigs are fed normal rations, that L-threonine will be the limiting essential amino acid.

A comparison in the period 120–180 lb. live weight between diets supplying 0·47 and 0·87% L-lysine, respectively, showed no benefit from feeding the higher amount. It seems uneconomic to feed animal-protein to supply lysine after 1201b. live weight. The requirement can be met at less cost from vegetable sources.

In conclusion, the author desires to express his indebtedness to Messrs V. Thurlbourn and R. D. Willis for taking charge of the experimental animals during the N-balance trial. Also to Mr E. A. Porter for his care of the pigs during the growth trial.

1. The effect of shelter from winter conditions was studied in terms of body-weight change of dry sheep individually fed a maintenance ration. In 2 years, one a mild and the other a hard winter, the exposed group lost weight relative to the sheltered group.

2. Within the treatments attempts were made to relate individual weight loss to a variety of fleece components. These results were not conclusive, but they suggest that such components as depth of wool and weight or volume of wool per unit area of skin have some effect in reducing weight loss under climatic stress conditions.

3. A method of measuring the insulation provided by the fleece in dry environmental conditions was developed. It was shown that exposure to moderate winds increased the heat flow by between three and five times. The results again suggested that significant differences in insulation could be found between sheep within a breed. It was not possible to demonstrate the overwhelming importance of any single fleece component.

1. A field experiment on an acid soil long in arable cropping at Rothamsted measured residual effects of superphosphate, applied at several rates, and Gafsa rock phosphate applied at a single rate. Residues were valued after 1 year with barley, and after 2 years with rye-grass. In each year, the value of the residues was related to yields from fresh superphosphate dressings taken as standards. ‘Percentage fresh superphosphate equivalents’ of the residues were determined using yields and P uptakes of both crops. An isotope dilution method with 32P was also used with barley. The experiment was continued for 2 further years without applying phosphate fertilizers, to measure yields and P uptakes from the residues and yields and P uptakes from rock phosphate relative to superphosphate.

2. ‘Percentage fresh superphosphate equivalents’ of residues of superphosphate for barley varied with the growth of the crop and with the method used to calculate them. They were 21–24%6 weeks after sowing, measured from yield, P uptake or isotope dilution. At harvest, they were 26% from yield, 43% from P uptake and 49% by isotope dilution. ‘Percentage fresh superphosphate equivalents’ 6 weeks after sowing increased with the rate of superphosphate but at harvest were independent of rate. ‘Percentage superphosphate equivalents’ of Gafsa rock phosphate were much smaller; they increased from 2–3% 6 weeks after sowing to 7–12% at harvest.

3. With rye-grass ‘percentage fresh superphosphate equivalents’ of residues of superphosphate applied either 1 or 2 years previously also varied with growth. All methods of valuation showed that residues were about twice as effective after 1 year as after 2 years in the soil. ‘Percentage fresh superphosphate equivalents’ derived from P uptake remained constant during growth and were 37–38% for superphosphate applied 1 year before and 18–20% for superphosphate applied 2 years before. Values derived from rye-grass yields decreased during growth from 76 to 45% (1-year residues) and from 38 to 21% (2-year residues).

4. After cropping with barley for 2 more years, there was little difference between yields or P uptakes from equal amounts of superphosphate whether applied 3 or 4 years previously. Residues from rock phosphate were almost equivalent to those from superphosphate after 3–4 years.

5. Apparent recoveries of superphosphate, as percentages of the amount applied, decreased with rate. The apparent recovery of P by crops in 5 years was about 21% from superphosphate and about 10% from rock phosphate when both were applied at 3·0 owt. P2O5 per acre.

1. When Merinos of varying wool lengths were exposed at constant air temperature of 36° C. (c. 97° F.) to infra-red radiation of energy equivalent to that which they might receive from the sun, the following responses were noted:

(a) A very highly significant (P < 0·001) inverse relationship between respiration rate and wool length.

(b) A non-significant inverse relationship between rectal temperature and wool length.

(c) A very highly significant (P < 0·001) quadratic relationship between back wool-tip temperature and wool length.

(d) A very highly significant (P < 0·001) inverse relationship between back-skin temperature and wool length.

Thus, the length of wool determines to a large extent the degree of protection given to the sheep against radiant heat.

2. The rate of conduction of heat per unit area through the back wool in different sheep was hyperbolically related to wool length. Below 1 cm. woollength heat was taken up very rapidly; beyond 4 cm., increasing wool length afforded negligible additional protection.

The errors of 454 cereal experiments organized by the National Institute for Agricultural Botany between 1956 and 1960 are examined in relation to block size. All the experiments used long, narrow plots and were harvested by combine. The most important conclusion is that the gain in efficiency by using small blocks in cereal experiments is as great now as it was before combine-harvesting and long, narrow plots were introduced. An empirical rule is that the variance per plot is roughly proportional to n½, where n is the number of plots per block.

1. Analyses and a greenhouse experiment on soils taken from a field experiment to estimate residual values of phosphates were used to show changes in the amount and distribution of residual phosphate in the soil.

2. Total and NaHCO2-soluble P were large in the top 0–3 in. of soil after applying superphosphate. Total P was large, but NaHCO3-soluble P much less, where rock phosphate had been applied in the field. Ploughing distributed total and NaHCO3-soluble P more uniformly through the 0–6 in. layer of soil.

3. Soil analysis and crop yields in the greenhouse showed that the residual value of equal amounts of P2O5 as rock phosphate and superphosphate, three years after application, were very similar.

4. At the end of the field experiment the sand fraction of the soil (2000–75 μ) contained about 80% of the phosphate that was applied as rock phosphate in this particle-size range.

Projects carried out in the Lake Province of Tanganyika for breeding Upland cotton resistant to bacterial blight are described.

A programme in which Albar 51 was used as resistant parent was more successful than one in which an attempt was made to transfer the major gene B6m to breeding stocks.

Backcrossing was found to be of limited value as a breeding technique with rain-grown cotton, line breeding in segregating stocks being preferred.

It is demonstrated that resistant types can be synthesized by the systematic exploitation of residual genetic variability in locally adapted populations.

Correlations between stem, boll andleaf resistance are discussed and some deviations attributable to environmental effects described. It is inferred that there is a basic resistance mechanism in all tissues which is under the same genetic control but that results may be confused by genotype-environment interactions and by other factors operating in particular tissues.

The approach to resistance breeding is discussed in relation to the evolution of resistance in African Upland cotton. It is concluded that improvement by straight selection should be given equal emphasis with improvement by hybridization in resistance breeding programmes.

1. Records are presented of observations of the sexual behaviour of indigenous Uganda cattle and the fertility to artificial insemination.

2. The mean cycle length found was 20·9 days,s.d.1·38 days. Mean length of oestrus was 2 hr. 14 min.

3. Marked pro-oestrus and metoestrus periods occurred averaging 14 hr. and 11 hr. 7 min., respectively. The mean total length of time that cows remained attractive to the bulls was 26 hr. 21 min.

4. The number of services and attempts to serve by three bulls was recorded and frequent small grunts were noted to be an important expression of excitement by the bulls.

5. The highest percentage of animals conceived to artificial insemination when inseminated between 15 and 25 hr. after commencement of pro-oestrus.