Simazine and prometryne applied to the soil surface in pots at 1·6 and 3·2 kg/ha. 2 days after sowing, did not affect germination or early seedling growth of chickpea. Reductions were noticed under all treatments in the leaf dry weight after 28 days and in the length of the main stem after 42 days. Dry-matter accumulation in the shoot was drastically reduced with simazine but not with prometryne. All treatments retarded dry-matter accumulation in the roots with time. Prometryne reduced chlorophyll content during early growth stages and simazine during later stages.

Growth of the rhizobial culture was reduced with increasing concentrations (1–20 mg/1) of both simazine and prometryne. Root nodule initiation was not affected by either of the herbicides but the later production of new nodules and growth of the nodules were reduced in different degrees by various treatments. Overall nodulation was drastically reduced with simazine. Reductions in nodulation with simazine and prometryne appeared to be primarily a case of general root growth reduction. The pink pigment, leghaemoglobin, did not develop at all in the nodules of simazinetreated plants and its concentration was not affected in the nodules of prometrynetreated plants. The N2-fixing efficiency (acetylene reduction) of the nodules was more in the case of prometryne-treated plants and was nil in the case of simazine-treated ones.

A grazing study, comparing a naturalized and a sown pasture at three stocking rates, was conducted under a uniform stand of 65-year-old coconuts on a fertile soil in the Russell Islands. In a plot trial on this site there was no significant response to application of up to 400 kg N/ha/year over 2 years to Brachiaria decumbens. Average daily transmission of photosynthetically active radiation through the coconut canopy was 60% of full sunlight. The sown pasture consisted initially of para (Brachiaria mutica), signal (B. decumbens) and koronivia (B. humidicola) with the legumes Centrosema pubescens, Pueraria phaseoloides and Stylosanthes guianensis. The main species in the naturalized pasture were Axonopus compressus, Mimosa pudica, C. pubescens and Colopogonium mucunoides. Pastures were set stocked in two replicates over 3 years at 1·5, 2·5 and 3·5 animals/ha. There was no significant difference in live-weight gain between pastures in any year. Live-weight gain per head declined linearly with increasing stocking rate. Highest live-weight gain was 437 kg/ha/year in the 1st year at 3·5 animals/ha. The planted grasses declined from 60% at the start of grazing to 6% 8 months later. A. compressus increased from 2 to 24% over 3 years in the sown pasture, and from 12 to 34% of yield in the natural pasture. M. pudica increased from 27 to 44% in the sown, and remained approximately constant at 37% in the natural pasture. G. pubescens increased at 2·5 animals/ha, but was replaced by P. phaseoloides at 1·5 animals/ha and by A. compressus and M. pudica at 3·5 animals/ha. There were no significant effects of pasture treatments or stocking rate on copra yields. Where there is a cover of naturalized grasses and legumes under coconuts, cultivation and planting of exotic species cannot be recommended. Major improvement will come from thorough weed control and maintaining stocking rates between 1·5 and 2·5 animals/ha.

The results are reported of two experiments made on a silt loam soil over chalk on downland in southern England. Three primary tillage treatments (ploughing, deep or shallow tine cultivation) were compared with direct drilling for their effects on the growth of spring barley during the years 1969–74 and winter wheat during 1974–8.

No significant differences in barley population density or early growth were recorded. In the first 2 years more grain was produced on the shallow tined and direct-drilled plots than on those that were ploughed, but the differences did not persist into subsequent years. The mean yield of each treatment over the 4 years did not differ.

Significant differences in population density and winter mortality of wheat occurred but these were not consistently associated with differences in yield. In this crop also the mean yields of the cultivation treatments over the 4 years were not significantly different.

It is concluded that choice of primary tillage system on this chalk downland soil was not a significant factor in the production of either spring barley or winter wheat.

The effects of variety, plant density and time of N application on the yield and yield components of winter wheat were investigated in factorial experiments during 1977–8 and 1978–9, at Sutton Bonington. Armada produced substantially fewer vegetative tillers/m2 but the number of ears/m2, from anthesis onwards, was similar to that of Maris Huntsman. The effects of the time of N application on tiller production and survival differed between the 2 years and may have been related to the amount of residual N in the soil. A linear relationship was found between the number of tillers/m2 which died and the maximum number of tillers/m2.

Kador produced a lower grain yield than Armada or Maris Huntsman, owing to a combination of lower ratio of grain D.M. to total above-ground D.M. (harvest index) and lower total dry-matter production. Armada produced a higher grain yield than Maris Huntsman in response to earlier application of N. Grain yield was less variable when final plant densities were greater than 200/m2.

Grain yield was not particularly well related to individual yield components but showed a good linear relationship with number of grains/m2. Grain yield was also linearly related to total dry-matter production, with treatment effects on harvest index being relatively small. The results indicate that factors which influenced crop growth during grain site development were relatively more important than the factors affecting subsequent grain filling.

Thirteen defoliation treatments were applied to a grass-white clover sward for 2 years to study some effects on the sward of cattle grazing compared with sheep grazing compared with various cutting treatments and to study the effect of height of defoliation.

Sheep actively sought out the clover in preference to grass whereas the cattle did not. The response of the clover to sheep grazing was a large reduction in the amount of stolon, shorter internodes, petioles and leaflets, and thinner stolon closer to the ground. Reducing the height of defoliation from 8 to 4 cm above ground level also reduced the dimensions of white clover. The clover, however, appeared to recover quickly and completely from the effects both of sheep grazing and of reducing the height of defoliation when these treatments were discontinued. In plots cut for hay the clover disappeared from the sward suddenly and completely in dry conditions following the 2nd-year hay cut. The effect of cattle grazing on white clover was similar to the effect of comparable cutting treatments. Cattle grazing, however, reduced the number of tillers of grass andincreased the proportion of bare ground, compared with cutting or sheep grazing. Grazing rather than cutting tended to encourage perennial ryegrass and to discourage Holcus. Cutting for hay encouraged Bromus mollis. Reducing the height of defoliation reduced leaf sheath and blade length and the rate of production of new blade per tiller in perennial ryegrass, but increased the numbers of tillers of grasses.

Analyses of data on first peak yields of 1346 Holstein Friesian (HF) × Sahiwal crossbred cows belonging to four Indian military dairy farms were carried out. There were highly significant differences amongst different grades. The < ⅛ HF had the minimum (9·35 kg) and £ HF had the maximum (12·77 kg) peak yield during first lactation. Half-breds appeared to be most suited for peak production. Genetic grades, farms and periods of calving had highly significant, and season of calving had significant, influences on peak yield in cross-bred cows. Heritability of peak yield was 0·405±+ 0·023. Peak yield had highly significant and positive genetic and phenotypic correlations with total lactation yield, 300-day milk yield, milk yield per day of first calving intervaland milk yield per day of age at second calving. Interval, in days, between the dates of first and second calvings was considered the first calving interval. Age, in days, at the time of second calving was considered age at second calving. The high heritabilities and desirable correlations indicate the possibility of satisfactory correlated response in thesetraits, if selection is based on peak yield.

Soil samples were taken from four field experiments on the growth of cereals in direct-drilled and in mouldboard-ploughed soil. When sampled, one of the experiments had run for 5 years, one for 6, one for 8 and one for 10 years. Sampling was to just below plough depth and was done on an ‘equivalent depth’ basis, i.e. the more compact direct-drilled plots were sampled more shallowly than the ploughed plots in such a way that both samples represented the same weight of soil per unit area. No significant differences in total nitrogen or in total organic carbon were observed between cultivation treatments at any of the four sites.

In three of the four sites, there was no significant difference in microbial biomass carbon, adenosine 5'-triphosphate (ATP), or mineralizable nitrogen between directdrilled and ploughed soils. In the fourth, which contained more clay than the others, there was slightly more biomass carbon and ATP in the direct-drilled soil. As microbial biomass carbon (or ATP, which is closely correlated with microbial biomass carbon) responds more rapidly to changes in management than do total carbon and nitrogen, a change in biomass carbon should provide early warning of changes in soil organic matter, long before changes in total carbon and nitrogen become measurable. That no such change was observed, with one partial exception, is evidence that a change from traditional methods of cultivation to direct drilling has little effect on soil organic matter other than altering its distribution in the soil profile.

Forty-eight approximately 18-month-old Scottish Blackface ewes were used to study the effects of two levels of nutrition during mid-pregnancy (30–98 days of gestation) on the birth weight of lambs from ewes varying in weight, size and condition at first mating. The mean live weight (42–4 kg), size index (31–9) and condition score (2–4) at mating of the 26 ewes from flock A were all less than those of the 22 ewes from flock B (54–5, 39–4 and 2–9 respectively). Mean intakes of the low and high nutritional treatment ewes during mid-pregnancy were 10–6 and 22–0 g/kg/day respectively of a pelleted diet supplying 8–81 MJ metabolizable energy and 125–5 g crude protein/kg. These intakes produced estimated changes in net maternal weight of approximately – 5 and 0 kg respectively.

Mean lamb birth weights from ewes on the low and high nutritional treatments were:flock A, 3–32 and 3–83 kg; flock B, 4–96 and 4–23 kg respectively. Analyses showed intake during mid-pregnancy to have a positive effect on lamb birth weight in the flock A ewes, and a negative effect in flock B ewes. Mating weight accounted for 78% of the variance in birth weight in the low nutritional treatment ewes but had little effect in those on the higher level of feeding.

The practical implications of the results are discussed in relation to levels of juvenile nutrition.

The feasibility of enhancing cotton (Gossypium hirsutum L.) growth and nutrient uptake with Temik aldicarb was investigated using sand culture with a continuous flow of 1/5 strength of Hoagland solution. Aldicarb was incorporated in the nutrient solution at different rates, and was applied to the plants when they were 30 days old for a period of 1, 3, 5, or 7 days. The cation exchange capacity of the fresh roots of treated plants as well as the ionic permeability of the untreated plants as influenced by aldicarb application were also studied. Low rate of aldicarb provided a stimulus effect on the plant and enabled it to grow faster and to take up more N, P, K, Ca, Mg, and Na than the control. This suggested a direct effect of aldicarb on mineral metabolism especially those processes involving N and P. Maximum dry-matter yield and nutrient uptake occurred at the 5 mg aldicarb rate for all times of treatments. At a rate of 7middot;5 mg aldicarb, growth and nutrient uptake were inhibited, suggesting a toxicity of assimilatory processes within the plant which might have reduced its ability to take up and assimilate nutrients. Aldicarb facilitated the transfer of Na to the stem and leaves resulting in a more uniform distribution of Na throughout the treated plants compared with the control.

On the cool semi-arid highlands of Kenya (1400–2500m) Boran cattle (Bos indicus) with dark coats predominate over white ones in pastoralist herds. Natural selection appears to favour dark-coated Boran cattle in these areas because significantly fewer black than white cattle die during drought and black cattle recover weight faster in wet seasons (Finch & Western, 1977). To investigate why cattle with dark coats are favoured, an experiment was designed to test whether the thermal effects of black coats in a cool climate interacted advantageously with the animal's metabolic economy. To date, interest in the metabolic significance of colour in cool climates has been confined largely to laboratory experiments (De Jong, 1976; Hamilton & Heppner, 1967; 0ritsland, 1971). The present experiment was different in that the thermal effect of coat colour on metabolic rate of cattle was investigated in the natural conditions in which they live.

The organic matter (OM) intakes of grazing ruminants can be calculated from the digestibility of the OM and faecal OM outputs which in turn are determined indirectly by administering known amounts of indigestible markers such as Cr2O3 (Langlands, 1975). The possibility that the C19–C32 fatty acids in fresh herbage could be suitable as an indigestible marker for determining intakes of grazing animals was examined. An early report had shown that when ‘Grasslands Ruanui’ perennial ryegrass (Lolium perenne L.) was fed fresh to sheep the C19–C32 fatty acids appeared not to be absorbed because their concentration increased from 7·2% of the total dietary fatty acids to 23·9% of the total faecal fatty acids (Body & Hansen, 1978).

Birth weight in goats is of prime importance as it provides a base for further physical and physiological development. Growth and subsequent production and reproduction traits are closely related to birth weight.

Very little work has been reported on Osmanabadi goats. The present investigation considers birth weights and growth rates of Osmanabadi goat kids.