1. A study has been made of some of the factors influencing the role of clover in grass-clover swards fertilized with nitrogen at different rates.

2. From 1955 to 1957 inclusive three nitrogen treatments, 0, 4 and 10 cwt. ‘Nitro-Chalk’ (15·5% N)/acre/season, were applied to twentyone grass-clover mixtures sown in the spring of 1954. The mixtures contained either S 184, S100 or Kersey white clover alone or in association with one of the following grasses, S 23 or S 24 perennial ryegrass, S143 or S37 cocksfoot, S48 timothy or S53 meadow fescue.

1. A brief description is given of an experiment in which some of the factors influencing the role of clover in grass—clover swards fertilized with nitrogen at different rates were studied.

2. Reference is made to a previous paper detailing the experimental methods and reporting the results pertaining to the effects of the grass varieties included in the seeds mixture on the yields of mixed herbage and of clover. The effects of the clover varieties on these yields are discussed in the present paper.

1. Ten experiments are reported in which the effect of high-level copper supplementation of pig rations on growth rate and food conversion was observed. In three of the experiments the study included observations on carcass quality.

2. In nine of the ten experiments a positive increase in the growth rate of the pigs receiving copper was recorded but the magnitude of this increase was markedly variable.

Semen characteristics and libido were observed for 34 months in German Merino, Persian Blackhead and indigenous ‘Native’ rams maintained on Rhodesian highveld. Birth rate from controlled service was determined during 23 of these months.

1. Breeding ability, as judged by semen production and libido, was continuous in all rams. A fluctuation in birth rate from controlled service was due more likely to seasonal variation in female fertility than in seminal fertilizing capacity.

2. Monthly changes occurred in all seminal characteristics but only those in sperm concentration were consistent between years. In all breeds spermatogenic activity was high in spring and mid-summer, low in late summer and autumn.

German Merino, Persian Blackhead and indigenous Native rams were exposed to gradually increasing day-length simulated by use of electric light in the night pen. Between February and June experimental day-length increased from 14 hr. 35 min. to 17 hr. whereas natural day-length fell from 13 hr. 50 min. to 12 hr. An additional trial was superimposed on the main experiment to determine the effect of vitamin A injections on reproductive function and on ability to respond to photoperiodic stimuli.

The effect of age on attainment of puberty and on seminal characteristics in yearling and mature rams was studied in German Merino, Persian Blackhead and indigenous Native rams living on Rhodesian highveld.

1. Puberty occurred at age and live weight proportional to mature live weight. Well-grown Native lambs ejaculated first at 169 days of age and 46 lb. live weight; Merino lambs when 250 days old and 79 lb. live weight and Persians were intermediate. Onset of sexual maturity was related more closely to live weight than to age, since runts ejaculated first at live weights close to those of well-grown lambs.

The effect of various diluents and different dilution rates on the maintenance of motility of ram sperm during storage at 4° C. was tested. Their efficiency was determined by half-life periods and total survival times of the sperm.

A yolk-glycine-citrate diluent maintained sperm motility for a longer period than did yolk—fructose—phosphate, yolk-citrate, cow's milk and ewe's milk, with or without yolk. This diluent has the advantage that the sperm is clearly visible under the microscope, and no sedimentation of any component occurs.

A modified IVT diluent prolonged the total life span of the sperm, but caused a faster motility decline in the first part of the storage period.

The daily intake of dry matter by zebu steers between 400 and 600 lb. live weight when fed hay and hay-concentrate mixture was investigated and found to be 2·0–2·2% of body weight.

Preliminary results of the nutritional values of Rhodes grass and Star grass hays are discussed and these suggest that the local zebu cattle require less starch equivalent for maintenance than do European cattle in temperate climates.

Peat soils change gradually as a result of drainage and cultivation, losing depth through shrinkage, oxidation and blowing, changing in character through increases in mineral matter and ‘drumminess’, and changing in productivity and manurial requirements. The sequence of changes has been studied in the field and a number of stages distinguished which may be recognized quite simply from the texture of the ploughed layer. Texture is a field assessment of the type and condition of the peat and the proportion and nature of the mineral matter associated with it. The Fenland soils have been classified as follows: (1) peat soils, (2) peaty mineral soils, (3) organic mineral soils and (4) mineral soils. Further subdivision into textural classes depends on recognizing the mineral combinations or fractions as in texturing mineral soils

Analysis of samples of the ploughed layer in the laboratory has shown that organic matter or loss on ignition figures, expressed as a percentage of the oven-dried soil, can be used for recognizing the kind of soil; use is made of this in considering those earlier experiments for which organic matter figures could be calculated.

A fine soil separate gave the highest and most rapid seedling emergence. This was considered to be due to its better moisture supply characteristics and the lower mechanical impedance compared with coarser seed-beds. There was no evidence that natural seed clusters are any less responsive to soil aggregate size than processed beet seed clusters.

Consolidation slightly hastened emergence, though the mechanism of this is not clear. Sowing at ¾ in. was superior to deeper sowing (1½ in.), both in speed of emergence and in ultimate emergence. This was partly an effect of decreased mechanical impedance, and partly due to the shorter period over which the seedlings were susceptible to pathogens. Heavy dressings of soluble fertilizers were found to delay emergence, though without effect on the ultimate emergence.

1. The availability of iron in three herb species 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 grama 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 three herbs.

Corriedale ewes in New Zealand on a constant ration throughout the year were subjected to various light treatments and their monthly growth of wool compared with controls having normal daylight hours.

1. In the controls the peak of wool growth occurred during November–January with long daylight hours and the minimum during June–August with short daylight hours.

1. The effects of restricting the daily grazing hours of indigenous cattle have been studied on grazing behaviour and cattle weights. The cattle grazed on natural veld.

2. Three cattle-management treatments, i.e. free range, moderate kraaling (11 hr. grazing day) and severe kraaling (7 hr. grazing day), were compared during seasonal periods of low cattle-weight gains, large cattle-weight gains and large cattle-weight losses.

1. The longissimus dorsi muscles of cattle have been analysed for moisture, intramuscular fat (and its iodine number), nitrogen (total, myofibrillar, sarcoplasmic, soluble non-protein and stroma), myoglobin, total soluble phosphorus and ash; ultimate pH and buffering power were also determined.

2. At birth, in the region of the 4th, 5th and 6th lumbar vertebrae, total, myofibrillar, sarcoplasmic and soluble non-protein nitrogens have attained 87, 76, 71 and 25% of their mean adult values, respectively; the concentration of stroma nitrogen diminishes by 50%, between birth and maturity.

3. The mean adult values (fat-free basis) for sarcoplasmic (0·9%) and myofibrillar (1·9%) protein nitrogen, for total nitrogen (3·6%) and for moisture (76·8%) are atained at approximately 5 months, 7–10 months and 18 months of age, respectively; moisture on a whole tissue basis decreases fairly regularly as intramuscular fat increases.

It is shown that the available energy, T.d.n. or S.e., contained in the dry matter of Kenya pastures at all stages of growth is remarkably constant. Thus in the early stages of growth of such pastures when the available D.c.p. is present in amounts suitable for very high milk yields the available energy limits their attainment. During later growth, as the amount of C.p. in the pasture becomes increasingly diluted by carbohydrate there is a progressive decrease in amount of available D.c.p. and it in turn becomes inadequate to sustain the original limited level of productivity.

1. An investigation concerning the weights twenty-four beef steers (three breeds—Hereford, Dairy Shorthorn and Friesians—on four planes nutrition), their grades, weights of organs, carcasses, tissues, etc., together with the chemical composition of their muscular and fatty tissues has been carried out.

2. The resultant data have been used to calculate—mainly by an analysis of variance—the effect of breed and level of nutrition. Only statistically significant differences are dealt with in this summary.

1. Seventeen experiments in 1957–59 on the Lincolnshire Limestone soils tested the response of sugar beet to 2·5 cwt. potassium chloride per acre (as commercial muriate of potash, 60% K2O) and its chemical equivalent in sodium chloride: 1·8 cwt. per acre. Average response of sugar yield to sodium was higher than to potassium, especially in the wet summer of 1958. There was a negative interaction between sodium and potassium; in the presence of sodium it was uneconomic to apply potassium.