The ability of subjectively assessed body condition scores, direct measurements of backfat depth, and an objective body condition index (based on the size/weight relationship), to predict the proportion of chemical fat in the body of the live sheep was investigated in three groups of Merino ewes. All three techniques possessed a similar, and practically acceptable ability to predict the proportion of chemical fat in the fleece-free empty body. However, both live weight and fleece-free empty body weight possessed similar predictive powers, and the method of choice in any particular situation could thus be determined by the availability of weighing facilities and the need for speed, objectivity and for minimizing interference with the experimental animals.

Macro-organic matter (roots and partially decomposed plant debris retained on a 0·25 mm mesh sieve) was measured in soils under various swards. Under a grazed perennial ryegrass/white clover sward, sown on arable land, macro-organic matter in the top 15 cm of soil rose steadily in the first 8 years to 15·8 t/ha, but subsequently declined. Under arable cropping there was great variation with crop and season. Under grass, most of the macro-organic matter accumulated in the top 2 cm of soil, particularly during the first 3 or 4 years. More macro-organic matter was found under perennial ryegrass/white clover than under cocksfoot/white clover swards.

After 3 years under grass macro-organic matter accounted for 10% of the total soil carbon, and represented about half the increase in soil carbon.

Half, or less, of the nitrogen which accumulated in soil under grass was in the macroorganic matter fraction. The differences between swards which received no N fertilizer and those which received 940 kg/ha over 3 years was small, 16–40 kg N/ha respectively for cut and frequently grazed swards. The ratio of C:N in macro-organic matter under different swards averaged 22:1.

The mean yield of grain of untreated spring field beans was 2750 kg/ha. By the use of differential defoliation, upper and lower limits were set for the photosynthetic contributions of four zones to this yield:

(i) stems and pods 0–300 kg;

(ii) leaves below first flowering node 280–1150 kg;

(iii) leaves on first nine flowering nodes 720–2100 kg;

(iv) leaves above first nine flowering nodes 260–1150 kg.

The evidence suggested that all zones functioned below their full photosynthetic efficiency when other zones were present and that competition between zones for sites to store carbohydrate was a greater limiting factor than mutual shading.

Soils and plants can absorb more S than is brought down in rain (Johansson, 1960). Much of the S absorbed from the air by light sandy soils (Mann, 1955) during the autumn, winter and spring is lost by leaching and only that absorbed by soil during crop growth can be used. The crop can also absorb atmospheric S directly through the leaves; the amounts may be larger than soils supply when crops have a leaf-area index larger than 1 (Olsen, 1957; Spedding, 1969).

For phase I of a rotational grazing experiment (three grazing cycles; May–July) a group of nine cows (group S) were ‘conditioned’ to eat fouled herbage by being allowed to graze only on slurry-treated pasture (area 1), and two further groups of nine (groups H and C) grazed on an adjacent area (2) of untreated pasture. One-third of area 2 was harrowed after each grazing. During phase II (the fourth grazing cycle; August) group H grazed on the harrowed part and groups S and C grazed on the remainder of area 2. The herbage allowance was 15 kg dry matter per cow per day in phase I and 12 kg in phase II.

In phase I, group S cows ate significantly less than groups C and H combined (9·2 v. 10·5 kg organic matter per day), and lost weight (– 0·37 v. + 0–03 kg/day), but their milk yields were not significantly lower (16·1 v.16–6 kg/day). In phase II neither intake nor milk yield differed significantly between the three groups, but group S cows gained weight while the other two groups lost weight.

It was concluded that neither conditioning the cows nor harrowing the pasture was an effective means of avoiding rejection of fouled pasture.

Oestrous cycle and phenomena accompanying oestrus were studied in the local fattailed Awassi ewe. By heat detections at 4 h intervals, the average period of oestrous was found to be 35·5 h and the mean duration of the oestrous cycle, 17·5 days. The repeatability of length of oestrus and of cycle length was 0·60 and 0·41, respectively. The appearance of a transparent or cloudy fluid secretion indicated that the ewe was still at least in the first half of the oestrous period, while that of a viscous creamy secretion indicated the approaching end of oestrus as well as the approaching ovulation; the latter events generally coincided. The onset of oestrus was not centred around any particular time of day.

Severe clinical copper deficiency has been recognized for some years on a number of farms within an area of 10 square miles in North Staffordshire. Response to injected copper is good and supplementation is now regular practice. One of the causes would appear to be a dietary excess of molybdenum, confirmed in soil and pasture.

Geochemical reconnaissance in 1965 delineated areas totalling 60 square miles, including the above area, in which molybdenum occurs in above normal concentrations in stream sediments, rocks, soils and pasture. The source of the molybdenum was found to be black marine shales of Carboniferous age. Within the areas the presence of molybdeniferous soils and pasture is related to local variation in geology and parent material and is in particular affected by drift cover.

Blood copper analysis on 350 cattle from 26 herds, excluding those herds in which deficiency was previously recognized, indicated hypocupraemia in 64% within the geochemically denned molybdeniferous area compared to 35 % in nearby control areas. Excluding animals fed minerals, the results were 77 and 37%, respectively. On the whole, deficient animals showed no marked clinical symptoms of hypocuprosis, though unthriftiness and poor fertility are common in the area.

Eight experiments investigated how different sowing and harvest dates, plant populations and fertilizers affect yield, germination and size of seed from hybrid monogerm sugar-beet seed crops, grown in situ when raised under barley cover in Lincolnshire, or open sown in Oxfordshire. Weather at seed harvest was wetter than average in 1968, average in 1969, and drier in 1970. Most seed of good quality came from plant populations of 300000 plants/ha sown in early July, given ample P and K fertilizer in the seed bed and 150–200 kg/ha of N in the spring of the second year in Oxfordshire or 200–250 kg/ha N in Lincolnshire. Harvesting in early September on average yielded most seed. Methods used to grow multigerm seed proved suitable also for monogerm seed but the percentage germination was lower for monogerm than multigerm seed.

Copper supplementation within the molybdenum-rich areas, on an exploratory basis in 1967 and in controlled trials in 1968, showed mean live-weight responses of 10–70% in dairy followers representing mean herd increases due to copper of 30–70 lb per animal over a 6-month grazing period. With few exceptions control stock showed no clinical symptoms of hypocuprosis.

Two methods of determining body composition in live cattle have been compared with the composition of the cattle as determined by chemical analysis. Total body water (TBW) was estimated from tritiated water (TOH) dilution, and circulating redcell volume (RCV) estimated from measurements of plasma volume and haematocrit. TBW was very closely related to fat-free weight and fat weight as a percentage of live weight (LW) in eight cattle ranging from 3 to 34% fat. TOH space was more precise than RCV in the estimation of the various chemical fractions of the live animal.

TOH injected intravenously equilibrated with ruminal water in 8–10 h; one could be confident that equilibration had occurred 10 h after injection, and equilibration time was not affected by previous restriction of feed and water. The mean biological half life of TOH was 4·2 ± 0·4 days. Equations are presented for the practical determination of the various compartments.

Yield, critical LAI and apparent photosynthetic rate per unit leaf area were measured in four families selected from L. perenne S. 321. Differences in yield were attributable to differences in canopy structure producing differing critical LAI. The most productive family, which was 33% more productive than the base population, produced the largest critical LAI but had the lowest photosynthetic rate.