1. Extremity skin temperature changes in British and Zebu cross cattle examined in moderate thermal environments followed a thermoregulatory pattern similar to that describedby Whittow (1962). At low environmental temperatures, ear and lower leg skin temperatures were usually only slightly above air temperature. At a variable time after air temperatures began to rise or the animals were fed, extremity skin temperatures increased suddenly to near trunk skin temperature.

2. In eight of the ten pairs of animals studied in rising ambient temperatures and during feeding after fasting for 36–72 hr, increases in ear temperature were measured in the British animal before similar changes occurred in its Zebu counterpart. Changes in lower leg skin temperature followed a similar pattern.

Trunk skin temperatures and respiratory frequencies were significant higher in British cross animals than in Zebu cross animals of similar thermal history. The mean rectal temperature of both British and Zebu cattle was 38·5 °C.

The histology of the skin follicles of a small group of Herdwick ewes was examined in midwinter and again in midsummer. In the primary follicles which remained active (about 9 % of the total follicle population) the ‘winter thinning’ in the fibre was accompanied by a thickening of the Huxley layer in the inner root sheath. In heterotype fibres (from primary follicles) a poorly defined crimp and a bilaterally differentiated cortex were present only in the thin length of fibre grown in winter.

The author is grateful to Dr. Marca Burns for permission to sample her Herdwick flock, and to Dr K. M. Rudall for helpful advice. This work was carried out while the author held a grant from the Agricultural Research Council.

1. Fifty-one experiments on the nitrogen, phosphate and potash requirements of maincrop potatoes were carried out in Great Britain in 1956–62. Each experiment tested four rates of each nutrient in all combinations and both total and riddled yields and quality data were obtained.

2. Nitrogen requirement was influenced by previous cropping and the rainfall during the preceding winter. 50–80 lb/acre of N are recommended in mixed farming rotations depending on winter rainfall, and 120–150 lb/acre of N in arable rotations.

3. Yield increases from phosphate were usually larger on soils with low citric-soluble phosphate. Nevertheless, irrespective of soil phosphate status, optimum rates of application were at least 120 lb/acre of P2O5 which was the highest rate tested in most of the experiments.

1. Nine successive trials with three adult desert rams were carried out, with the aim of using ruminal ammonia or blood urea concentration as an index of the nutritive value of the proteins in the various types of forage grown in irrigated parts of the northern Sudan.

The change in the ruminal ammonia and blood urea concentration were considerably higher 3 h after feeding on leguminous forages than on the non-legumes. Among legumes, lubia and lubia hay produced the highest concentrations of both rumen ammonia and blood urea. Feeding the rams on berseem hay reduced the concentrations of ruminal ammonia and blood urea to levels below those given by feeding on fresh berseem.

3. Most of the nitrogen excretion from leguminous forages was in the form of urinary nitrogen whereas for grasses faecal nitrogen made up the bulk of the nitrogen excreted. Berseem hay gave the highest nitrogen retention, followed by the butterfly pea and fresh berseem. Lubia and lubia hay gave the lowest nitrogen retention. The desert grasses produced a negative nitrogen balance when offered to the desert rams.

1. The growth of lambs grazing tall fescue pastures, receiving high and low levels of nitrogen fertilizer, was studied.

2. fertilizer, was studied. final body composition was estimated. Rumen liquor samples were collected three times and herbage intake estimated five times during the 88-day experiment.

3. On clipped herbage samples, O.M. digestibility was estimated in vitro, and chemical composition was determined.

4. Live-weight gain, final body composition and D.o.m. intake did not differ significantly between treatments. Molar proportions of acetic acid were higher and n-butyric acid lower on the high nitrogen treatment.

The effect upon the onset of reproductive activity of exposure of ewe lambs of three British breeds (Border Leicester, Southdown, Suffolk) to constant long daylight hours (16 h light/8 h dark) was studied.

Oestrus, ovulation and conception were depressed but not inhibited; however, only the incidence of conception was significantly less than in the control group. Athough the treatment retarded the onset of oestrous activity, the age at first oestrus was still within the normal age range for puberty.

During the last ten years or so, the management of sheep for intensive lamb production has been studied on a considerable scale, and a variety of grazing systems have been investigated (Dickson, 1959; Cooper, 1959; Spedding & Large, 1959; Boaz, 1959). It is still too soon to specify precisely the place that any of these systems should occupy in sheep-production processes, in relation to breed, lambing percentage, weight of lamb at slaughter, stocking rate, botanical composition of the pasture, size of ewe and level of her milk yield. Quite apart from these biological considerations, the full economic implications are by no means clear. What has emerged most clearly, however, is that much higher stocking rates can be tolerated than had generally been regarded as safe and that, at these stocking rates, productivity can be extremely high.

1. The heat tolerance and walking performance of bulls, steers and heifers exposed to moderate heat stress have been compared, following the method of Yeates & Murray (1966). Hereford cattle aged 14–16 months were used in the experiment. Two speeds of walking were employed and the effect of clipping the coats of both exercised and stationary cattle was studied.

2. In the undipped state, at both speeds of exercise (1⅔ and 2⅔ m.p.h.), the heifers performed best followed by the steers and bulls in that order, judged by their ability to preserve normal body temperature.

1. In a 2×3×3 factorial experiment a total of seventy-two female or castrated pure Friesian, Charolais × Friesian and Welsh Black × Friesian cattle were fed individually and ad libitum on three diets from 200 lb to slaughter at 800 or 900 lb, depending on sex. The diets were ground barley (87%) and protein-mineral-vitamin supplement (13%) given with or without 1 lb of hay per animal daily, or ground maize (87%) and supplement (13%) given with 1 lb of hay daily.

2. The three breed-types differed significantly in growth rate and feed conversion efficiency. Gaining at 2·66 lb/day and converting 4·56 lb of meal into 1 lb live-weight gain, the Charolais crosses grew 7·7 % faster than pure Friesians and consumed 14·1% less meal per unit gain. Welsh Black crosses made 9·3% less rapid gains and required 7·7 % more meal per unit gain than pure Friesians. The disparity between the three breedtypes increased with increasing liveweight.

In a series of five irrigated cotton sowings (T2, T7, T9, T11, T14) evapotranspiration (Et) was determined for the period between October 1961 and October 1962 by observing frequently the changes in soil moisture storage, calculating through drainage, and solving for evapotranspiration in the water balance equation. Thus a water balance was obtained for each sowing extending over the entire crop.

The average evapotranspiration in wet season sowings was of the order of 6·5 mm day−1 and in dry season sowings of the order of 4·5 mm day−1. The highest evapotranspiration values ranged between 10 and 12 mm day−1 in T2, T7 and T9 and between 7 and 9·5 mm day−1 in T11 and T14.

1. The effect of seed rate on yield of grain and its components in four contrasting oat cultivars, Maldwyn, Milford, Victory and Marvellous, was investigated over 3 years. At the high (206 lb/acre) and medium (137 lb/acre) seed rates, the final grain yield was similar within each of the three seasons. The low seed rate (69 lb/acre) gave significantly lower yields than the medium or high rates in 1955 and 1957, and in the latter year there was a significant cultivar × seed rate interaction.

The growth and development of five winterwheat varieties and of random selections from hybrids between them were compared. Successive sampling demonstrated varietal differences in orthogonal polynomial regression coefficients fitted to data for tiller number, shoot weight and leaf area. The correlation coefficients between these parameters and yield were statistically significant, but when polynomial regression equations of yield on them were determined, only the terms relating to shoot weight and leaf area duration after anthesis were significant.

The heritabilities of these parameters in each of 2 years were determined from measurements of genetic and environmental variance. The results obtained were compared each year with estimates of yield derived from parameters determined in the other year. The correlation between successive estimates of yield was found to be closer than that of of yield was found to be closer than that of yield with any of the growth parameters.

Separate analyses of crosses involving each of the parental varieties showed seasonal and varietal differences in the usefulness of the growth parameters for predicting yield.

The value of this approach to the choice of parents is discussed in view of these findings.

1. Plant nutrients, N, P and K, were applied to the soil surface or injected at a depth of 18 in. or 30 in. in perennial ryegrass swards, when the upper horizons of the soil profile were dry.

2. When the surface soil was dry and a soil water deficit of 2 in. existed there was no response to surface applied N but injection of N into moist soil at a depth of 18 in. produced a marked increase of growth. At this depth of injection there was a significant positive interaction between N and PK.

3. There was a substantial recovery in the herbage (59–80%) of the nitrogen applied to the subsoil, provided water was available in the soil horizon in which the nitrogen was applied.

4. Failure of a grass sward to regrow after cutting when the water available to the plant has been removed from the uppermost soil horizons is largely due to a deficiency of plant nutrients in the subsoil. The major deficiency is that of nitrogen.

Three tests—two winter and one summer—involving 134 growing-finishing pigs showed no response to germicidal ultraviolet radiation. The pigs received no direct sunlight and were irradiated nearly continuously for periods of 54–70 days. Lamps with a 2537 Å output of 5·2 W were provided at rates of one lamp per 11·1 m2 in two tests and one lamp per 3·35 m2 in one test.

1. The nitrogen content of an arable soil to 15 cm depth, sown to a ryegrass/white clover sward increased on average by 0·005 % N each year.

2. Under a grass sward without clover and without fertilizer nitrogen, there was an increase of 0·017 % N in 3 yeais in the top 7·5 cm of soil; an annual addition of about 70 kg N/ha.

3. Including white clover in grass swards not receiving nitrogen fertilizer resulted in an increase over 3 years of 0·026% N to 7·5 cm depth in one experiment, and 0·014% N to 15 cm depth in another, an annual increment of 100–110 kg N/ha.

4. The increase was greater under ryegrass/white clover swards than under cocksfoot/white clover swards. A similar difference was found both in accumulation of organic carbon and in clover content. In an experiment comparing many different grasses it was not possible to distinguish differences in the level of soil nitrogen, after 4 years under grass, which could be ascribed to species or strains.

There was no significant effect of nitrogen fertilizer applied at rates of up to 314 kg N/ha per year for 3 consecutive years.

Urea nitrate, urea phosphate, and a mixture of urea phosphate and urea were tested as nitrogen fertilizers to find whether the presence of the anion decreases the damage urea causes to germinating seeds and seedlings and increases the efficiency of urea by preventing loss of ammonia.

Urea nitrate was compared with ammonium sulphate for grass grown in pots in the glasshouse and with ammonium nitrate for permanent grassland in the field. In the glasshouse, a large dressing of urea nitrate damaged the early growth of grass in sandy-loam soil. On average of sandy-loam and clay-loam soils with a small dressing of fertilizers, grass recovered similar amounts of N from urea nitrate and ammonium sulphate; with the large dressing it recovered less from urea nitrate.

In the field, 100 and 200 lb N/acre were applied to permanent grassland which was cut twice. The herbage was ‘scorched’ by the urea nitrate because its solution is very acid. Urea nitrate at 200 lb N/acre produced less dry matter containing less nitrogen than did ammonium nitrate.

Urea nitrate, urea phosphate and urea phosphateurea mixture were compared with ammonium nitrate for barley and grass grown in clay-loam and sandyloam soils. Tests were made of 33, 67 and 100 lb N/acre for barley and 100, 200 and 300 lb N/acre for ryegrass; the fertilizers were applied immediately before sowing. On the light Woburn soil early growth of barley was least good with urea nitrate, which also damaged the early growth of grass.