The tissue copper concentrations of Black Najdi sheep at the Hofuf Agricultural Research Centre (HARC) are reported. Lambs suffering from a delayed neonatal ataxia had low concentrations of copper in blood, liver and kidney, consistent with a diagnosis of copper deficiency, which was supported by histological examination of their brains and spinal cords.

Low concentrations of copper and high concentrations of molybdenum and sulphate in forages produced at the HARC appear to contribute to the high incidence of neonatal ataxia observed there.

The parenteral administration of 40 mg of copper to pregnant ewes improved the viability and weight increases of lambs over lambs born to untreated control ewes, even though all lambs had received an injection of 20 mg of copper soon after birth.

The provision of supplementary barley to the lambs running with their mothers and with access to lucerne hay increased their growth and blood copper concentrations over animals restricted to the hay diet.

The blood copper, haemoglobin and packed cell volumes of lambs born to ewes maintained on Rhodes grass were significantly lower than lambs born to ewes given lucerne, all ewes having received copper during pregnancy. This effect was attributed to the low copper and high molybdenum and sulphate content of Rhodes grass (Chloris gayana).

Visible symptoms of copper deficiency in cereals have been observed in several parts of Britain and described by Caldwell (1971) and others. However, several cases have also been reported where yield increases of up to 20% or more have been obtained in response to copper treatment in several types of crops which did not show any symptoms of deficiency. These subclinical deficiencies are frequently not recognized under ordinary farming conditions where poor yields can often be ascribed to other causes, such as water stress. Copper applied as a foliar spray has powerful fungicidal properties but the yield responses discussed here were only due to the nutritional effects of the element. In trials with foliar applications of copper, Reith (1968) reported yield increases averaging 20% in oats and barley at different sites in Scotland on sandy soils formed on glacial drift.

Thirty-six Friesian and Friesian cross-bred cattle about 11 months old were fed to grow at the rates of 0·50 (low) and 1·08 (high) kg/day in a 12-week winter feeding period and then turned out on high quality pasture. For 12 weeks after turning out the ‘low’ and ‘high’ animals gained weight at 1·17 and 0·90 kg/day respectively. There was a negative correlation (– 0·57, P < 0·01) between winter and grazing live-weight gain.

On two occasions herbage intake was estimated. Average intake of ‘low’ animals was 12% higher than of ‘high’ animals although herbage digestibility, estimated from faecal N, was similar for the two treatments. Differences in live-weight gain on pasture between treatments were largely accounted for by differences in intake.

The low rate of winter growth did not have any significant effects on age at slaughter, carcass weights or grades attained by the restricted animals.

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.

Beverage tea is produced from the immature shoots manually harvested from the perennial shrub Camellia sinensis (L.) O. Kuntze. Fresh green leaf is mechanically comminuted and converted to the black tea of commerce by a series of partially controlled biochemical oxidation reactions (Sanderson, 1972). The final, unrefined dried product represents some 20% of the initial fresh weight of crop, the actual dry-matter content of the harvested shoots determining the percentage made-tea return (Keegel, 1955). Dry-matter content, hence, influences yield in terms of black tea produced. Although theeffectsof environmental, agronomic and cultural factors on green leaf yield have been studied intensively, little work has been done on the influence of such factors on dry-matter content. The present study examines the effects of nitrogen application rates on dry-matter content in four genetically diverse clonal populations throughout the main production season and during the first period of the Central African off-season.

Much attention has been given to the use of urea in ruminant feeds since the demonstration by Hart et al. (1939) that non-protein nitrogen (NPN) compounds could be a substitute for protein in ruminant rations. However, the high activity of urease in the rumen decreases the efficiency of urea utilization, because the rate of ammonia release from urea is much faster than the rate of its assimilation by rumen microbes for the synthesis of amino acids (Bloomfield, Garner & Muhrer, 1960). Moreover, if the concentration of ammonia exceeds a certain limit, it causes toxicity to the animals (Froslie, 1977). The efficiency of urea utilization can be increased if the rate of ammonia production is similar to the rate of its assimilation by rumen micro-organisms. This could be achieved either by decreasing the activity of the rumen urease or by modifications of urea in products which result in slow release of ammonia (Helmer & Bartley, 1971). Attempts have been made to increase the efficiency of urea utilization by complexing urea with carbohydrates (Daniels et al. 1971; Muhrer, Harris & Bloomfield, 1968; Shultz, Shultz & Chicco, 1972), sodium bentonite (Britton, Cooling & Klopfenstein, 1978) and carboxy resin (Huston, Scherton & Breuer, 1974). Formaldehyde is known to protect proteins from rumen degradation by its reaction with terminal amino groups (NH2), the e-amino groups of lysine and a number of other side-chain groups of proteins (Barry, 1976; Van Dooren, 1972). Urea contains two amino groups for undergoing chemical reaction with HCHO to give different complexes. Previous work in our laboratory has shown that urea could be complexed with HCHO (Lall et al. 1980; Pal & Negi, 1977). However, in those studies excesses of urea and HCHO were not removed and this produced an artefact in the evaluation of the ureaformaldehyde complexes (UFCs). Moreover, whole rumen fluid was used for in vitro ammonia formation from these complexes. No studies have been made so far in a well-defined system on the biochemical basis of the ammonia-releasing property of the UFCs. We report here the formation and isolation of UFCs, free from urea and HCHO and their hydrolysis with purified rumen urease (EC. 3·5.1.5). Evidence is adduced that UFCs are substrates for rumen urease and can act as slow ammonia-releasing compounds.

Recently it has become evident that the estimates of crop losses by biotic and abiotic agents are not adequate for present-day requirements. With the increasing awareness of the need for more accurate and reliable crop loss estimates within both administrative and scientific disciplines, there has been an enhanced interest in the precision of disease measurement.

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 extent to which proteins fed to ruminants are degraded in the rumen is determined by their rate of degradation and retention time in the rumen. It is known that retention times in the rumen are much longer for poor quality than for good quality roughages. Thus, it is possible that protein supplements may be more extensively degraded when fed with poor than when fed with good quality roughages. The present experiment was designed to determine the relationship between retention times of roughages and a protein supplement fed with them.

It appears that in ruminant animals one of the important effects of rumination is to decrease the particle size of the diet (Pearce & Moir, 1964; Gordon, 1968; Welch & Smith, 1969). This thesis is borne out by Gordon (1958) who showed that grinding a dried-grass diet markedly reduced rumination. Therefore, it is fair to assume that rumination behaviour is, at least in part, concerned with changing the physical properties of food, especially roughage, so that digestion and utilization are improved. Fujihara (1980) observed more efficient rumination in fresh-grass feeding than with hay in sheep given either fresh grass or hay alone, diets clearly differing in physical properties.

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).

The Indian subcontinent has witnessed a spectacular improvement in yield of wheat during the past decade (Rao, 1978). This is reflected in the improvement of the average national yields as well as of those regions where wheat is grown as an irrigated crop (Sinha & Aggarwal, 1981). However, after the release of the double dwarf variety Kalyansona, only marginal improvement in yield has occurred in recent years. Despite this, the semi-dwarf character continues to be considered a major factor for improvement of wheat. Asana & Chattopadhyay (1970), Konar & Asana (1975), and Wattal & Asana (1976) observed no significant difference in yield between tall and semi-dwarf (medium tall) varieties in pot culture experiments where lodging was prevented and competition was partly reduced. They ascribed prevention from lodging and improvement in the ratio of grain to total above-ground dry matter as major advantages in the modern varieties. Somewhat similar conclusions have recently been drawn by Austin et al. (1980). However, a detailed comparison of various physiological and biochemical characters lias not been made to determine whether any advance has occurred in basic processes such as photosynthesis and nitrogen assimilation. The present study was an effort in this direction.

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.

Field experiments with chick peas (Rawat & Sanoria, 1977) and peas (Sanoria & Ram, 1979) showed a synergistic effect of a particular Rhizobium and Azotobacter on yield and quality of seed. Isolates of R. leguminosarum revealed differences in the yield and quality of lentil grown in pots and in the field (Mallik & Sanoria, 1980). As there is no evidence in the literature regarding the simultaneous use of Rhizobium and Azotobacter on lentil (Lens esculenta), this study was undertaken to assess their effect on the yield and quality of lentil in field.

Current means of improving the efficiency of beef production in the United Kingdom include the use of hormonal anabolic compounds and the feed additive monensin sodium (monensin, ‘Romensin’, Elanco). Results from studies conducted mainly in the United States have shown that monensin may improve food conversion efficiency (e.g. Broome, 1980) which occurs as a result of variable reductions in food intake with or without increases in growth rate. These effects have been associated with alterations in the production of volatile fatty acids and methane in the rumen. Other studies have suggested that protein metabolism may also be affected (e.g. Pendlum, Boling & Bradley, 1980).

Zinc deficiency is widespread in Indian soils (Kanwar & Randhawa, 1974). The critical limit of Zn varies for different soils and crops (Katyal, 1978). There is no information on the critical value of Zn in calcareous soils of Bihar for maize, a major food crop of this region, and the present study was planned to determine this so that responses to applied Zn could be predicted.