Ten yearling red deer stags (Cervus elaphus) and ten yearling Coopworth wether sheep were housed in individual pens and offered ryegrass-white clover silage, containing 9–10 mg Cu, 1·4–1·7 mg Mo and 2·4 g S/kg D.M., in amounts close to maintenance energy requirement. For six animals of each species the diet was enhanced with 4·8 mg Mo and 3 g S/kg D.M. Liver biopsy samples were obtained during weeks 1, 6 and 12. The animals were then re-randomized and five of each species offered the basal diet and the remainder the basal diet supplemented with 4 mg Cu/kg D.M. Liver biopsy samples were obtained after a further 4½ weeks. Plasma samples for estimation of total and trichloroacetic acid-soluble Cu were taken weekly.

The mean liver Cu concentration in sheep was 11-fold greater than in deer. Both diets induced liver Cu depletion, though there was a trend for a greater rate of depletion on the Mo- and S-enhanced silage. The rate of depletion (mg Cu/kg liver D.M./day) was 7-fold greater in sheep than in deer, although it was not possible to determine whether this reflected a species-, as opposed to a Cu status-induced effect. In both species highly significant linear relationships were observed between initial liver Cu concentration and rate of liver Cu depletion. This was interpreted to indicate that endogenous loss was directly proportional to liver Cu content in both species. Individual estimates for the minimum rate of endogenous loss of Cu (μg/kg W/day) ranged from 0·2 to 2·71, mean 1·43, and from 2·83 to 14·75, mean 8·35 in deer and sheep, respectively.

During repletion the rate of increase of liver Cu in supplemented groups tended to be greater in sheep than in deer and calculated minimum values for availability of Cu were 0·061 and 0·037, respectively.

Liver Cu concentrations of less than 20 mg/kg D.M. were maintained in deer for several weeks without apparent symptoms of deficiency.

The effect of oestradiol-17β on the response to fishmeal supplementation of grass silage was studied in young growing cattle. Voluntary intake and live-weight gain were recorded over 63 days with 36 British Friesian male castrates (initial live weight (LW) 119 kg) offered silage alone (C) or with 50 (FM1), 100 (FM2), or 150 (FM3) g fishmeal/kg silage dry matter. Twelve calves were allocated to each of treatments C and FM3 and six to treatments FM1 and FM2. Half of the calves on each treatment were ear-implanted with oestradiol-17β (Compudose 365) at the start of the experiment. The calves on treatments C and FM3 were slaughtered after 75 days and chemical analysis conducted on half of each carcass. The silage had an organic-matter digestibility in vivo of 0·794 and was well-fermented, with a pH of 3·7. Intake averaged 24·2±0·42 g D.M./kg LW over all the treatments and live-weight gain was 0·77 kg/day on the silage alone. There was a significant (P < 0·05) interaction between fishmeal and oestradiol-17β, such that response to the hormone was observed only in the presence of fishmeal at 100 or 150 g/kg silage D.M. A similar interaction was apparent between fishmeal at 150 g/kg silage D.M. and oestradiol-17β in the final weights of empty body and carcass. This level of fishmeal also increased protein gain from 96 to 147 g/day and this was further increased to 179 g/day in the implanted animals receiving fishmeal. However, the overall effect of oestradiol-17β on protein gain was not significant. Gross efficiency of energy utilization was significantly (P < 0·01) increased by fishmeal supplementation suggesting an improved balance of nutrients compared with the silage alone diet.

In a 3-year plot experiment on a perennial ryegrass plus white clover sward the pH of the soil on the main plots was adjusted to, and maintained as nearly as possible at, target levels of 5·25, 6·00 and 6·75 by applying either sulphur or lime. Within the main plots the effects on herbage yield, clover content and crude-protein content of applying four fertilizers were compared at nitrogen rates of 225 and 450 kg/ha annually. The fertilizers were liquid manure (urine plus water), prilled urea, a urea solution and an ammonium-nitrate fertilizer. The applications of the urea and the ammonium-nitrate fertilizers were accompanied by dressings of a potassium fertilizer which supplied the same weights of potassium as in the liquid manure. On average the smallest yields of dry matter and crude protein were associated with the lowest soil pH with no significant interactions between pH and fertilizer treatment. The liquid manure gave slightly smaller total yields of mixed herbage dry matter than the other fertilizers, particularly at the low nitrogen rate. The herbage from the liquid manure treatment had a higher clover content and produced a greater total yield of clover dry matter. The effects of the liquid manure on the clover agree with those noted in previous experiments, but no evidence was found that these effects resulted from the liquid manure increasing the pH of the soil and improving the conditions for clover growth. Similarly, no proof was obtained that the clover effects were due to the nitrogen in the liquid manure being wholly in the ammonium form. However, the value of liquid manure as a fertilizer for grassland was demonstrated clearly.

Two Rhizobium strains and five lentil genotypes were most salt-tolerant under various salt stress conditions and strain LC 6 was the most sensitive. Salt-tolerant strains were more antibiotic-resistant and showed higher relative rates of oxidation of carbohydrates and tricarboxilic acid intermediates. The content and concentrations of root exudates of lentil genotypes were different and found to be attractants for the Rhizobium strains. Under salt stress, significant interactions between salt-tolerant strains and genotypes resulted in different responses of nodulation and host plant growth measurements.

The development and proportions of muscle, fat and bone were studied in 341 entire male and female Iron Age (European Wild Pig × Tamworth), Pietrain and Large White pigs ranging in live weight from 12 to 370 kg. The number of pigs was: Large White, 138 entire males and 112 females; Pietrain, 41 entire males and 31 females; Iron Age, eight entire males and 11 females. The breeds and sexes were compared in terms of the allometric growth coefficients of tissues (b) and of tissue weights at constant side weight and constant weight of total side bone.

At the geometric mean for side weight (26·5 kg), Pietrain carcasses had the most muscle (16 kg), followed by Large White (15kg) and Iron Age (11 kg), but the least fat (6 kg). Large White and Iron Age carcasses had 7 and 12 kg of fat, respectively. Relative to side weight, the earliest maturing tissue, bone, was particularly slow growing in Iron Age pigs (b = 0·627) and relatively fast growing in Large Whites (b = 0·801). The opposite was true for fat, the latest maturing tissue, and consequently Iron Age (b = 1·345) and Large White (b = 1·164) pigs were identified as early and late maturing, respectively. Pietrains had a higher growth coefficient for fat relative to side weight (b = 1·249) and lower growth coefficient for bone (b = 0·713) than Large Whites. The difference in percentage fat between Pietrains and Large Whites decreased slightly between 65 and 120 kg live weight. In terms of tissue growth patterns, Pietrains therefore demonstrated early maturing characteristics compared with Large Whites, and it is possible that a low voluntary feed intake under ad libitum feeding conditions prevents them from expressing these characteristics in terms of percentage of fat in the side. Pietrains had a particularly high muscle:bone ratio (6·2 at the mean side weight) compared with Large White (5·2) and Iron Age pigs (5·3).

The difference in carcass composition between entire males and females was breeddependent. Entire male carcasses were slightly leaner overall and had a lower muscle: bone ratio than those of females, but tissue allometric growth patterns were similar in the two sexes.

This management-oriented study of range, livestock and Maasai ecology in the wildlife conservation and pastoralist land use Ngorongoro Conservation Area (NCA) quantifies spatial and temporal variation in range resources for three main study sites over a 2-year period. Livestock response is analysed in terms of biomass densities, habitat and pasture utilization, activity, herd size, composition and dynamics. Milk production is investigated together with the main ecological factors influencing yields. A household survey of the Maasai food system suggests that pastoral products now provide an annual average of 40% dietary energy intake, the remainder being supplied by grain. These findings form the basis of our analysis of the growing friction between the Conservation Authority and the pastoralists. Pastoralist livestock closely resemble wild ungulate utilization of NCA range resources. A combination of disease interactions and administrative restrictions allow wildlife to establish preferential access to critical grazing resources. Our results in the context of other work suggest that contrary to popular opinion pastoralist land use is an ecologically appropriate and efficient form of livestock management. There is no adverse impact on the conservation values of NCA. Despite average fertility and mortality levels pastoralist herds show progressive decline due to offtake for grain purchase. Imposed policies restrict grazing, ban cultivation and maintain poor conditions for livestock trade and grain supply. Possible interventions and their potential impacts are considered and management compromises which could benefit both pastoralists and wildlife are proposed.

Soil NO3-N and NH4-N were measured to 90 cm depth in autumn and again in spring, under several sets of winter wheat experiments, on contrasting sites. Crop samples were taken throughout the growing season, both before and after the fertilizer N was applied, to measure N uptake. The amount of NO3-N in soil at the outset of growth in autumn was related to the uptake of N by wheat not given any fertilizer N until April.

The effect of sowing date (September v. October) on both crop and soil N was compared, as also was the effect of soil type (retentive of NO3-N v. readily leached) and previous crop (potatoes v. oats and wheat v. beans).

The amounts of NO3-N in the soils in autumn related well with previous crop and declined gradually during winter on the heavier soils, but rapidly on the sandy soil, in the latter case as a consequence of leaching. On the heavier soils, where little leaching occurred, the decline in soil NO3-N related well with the amount of N taken up by September-sown wheat during autumn and winter, but not with that taken up by October-sown wheat, where NO3-N accumulated in the soil during winter, because uptake was so small. Hence delayed sowing enhanced the likelihood of losses of NO3-N by leaching or by denitrification. On the sandy soil at Woburn, whilst the September-sown wheat removed more N than the October-sown, losses of NO3-N by leaching were severe, so that late winter growth was restricted by shortage of N in soil, and the amount of N taken up was far smaller than at Rothamsted.

The soil measurements distinguished between the NO3-N residues remaining after beans or wheat in the same field and between residues after oats or potatoes on soils of the same soil series, but in different fields on the same farm.

The amount of NO3-N in soil and the N taken up by wheat in February-March were together used to adjust the amount of fertilizer N applied in April, using a balance sheet approach to meet a specific yield objective. Some of the N uptake data from these experiments are presented. This should aid the calculation of N requirement during specific growth periods and thus help improve the prediction of fertilizer N dressings in spring.

Forty-eight sows were partially hysterectomized on day 10 (day 0 = 1st day of oestrus) of the oestrous cycle such that the isolated-contralateral ovary received either an ovarian or an ovarian and uterine blood supply. These two treatments were examined for their ability to affect corpora lutea (CL) function when 10, 20, 40 and 80 cm (12 sows/group) of the ipsilateral uterine horn remained intact. Sows with only 10 cm of uterine tissue failed to return to oestrus when observed until day 40. When 80 cm of uterine tissue remained, all the sows recycled between days 20 and 24. As the length of uterine horn increased from 10 to 80 cm the contralateral ovary became susceptible to luteolysis. At these lengths (20–40 cm), increased blood supply to the contralateral ovary afforded the luteal cells resistance to luteolysis (uterine length × blood supply interaction, P < 0·05). An additional four sows received 125I-labelled microspheres for purposes of determining CL blood flow following these alterations of blood supply to the isolated ovary. Blood flow to the CL was increased in three of the four sows when the isolated ovary received an additional uterine blood supply. Results from these experiments support the concept of an involvement of blood flow in the regulation of CL function.

The proportions of cross-bred and selfed seed were estimated in up to four consecutive generations of Throws MS winter beans on three farms where farm-saved seed was regularly used.

Within one stock the percentage of cross-breds rose a significant amount from 31 to 46, whilst in another stock no change was detected over four consecutive generations. On the third farm a change of stock mid-way through the period of the survey was associated with a highly significant increase in proportion of cross-breds.

In general a rise in outcrossing was not followed by a significant fall as would be expected if cross-breds have a greater tendency than inbreds to self pollinate, but the possible role of a regulatory mechanism is discussed as are implications of the range in outcrossing within stocks for variety trials and commercial production of winter beans.

Estimates of outcrossing frequency made in two crops in 1983 were slightly lower than some obtained in 1974–6 but no lower than those reported in 1951 thus providing no evidence of any long-term change in levels of natural cross-breeding in field beans in England.

In 1984 and 1985 a field experiment on a grass ley on a light sandy soil at Woburn Experimental Farm, Bedfordshire, tested injected aqueous urea and broadcast prilled urea, applied alone or with a nitrification or urease inhibitor. Aqueous urea, prilled urea and ‘Nitro-Chalk’ were applied as a single 375 kg N/ha dressing, and prilled urea and ‘Nitro-Chalk’ also as three 125 kg N/ha dressings. The nitrification inhibitor nitrapyrin or a mixture of sodium trithiocarbonate (STC) plus potassium ethyl xanthate (KEtX) was injected with aqueous urea. The nitrification inhibitor dicyandiamide (DCD) or the urease inhibitor phenyl-phosphorodiamidate (PPDA) was broadcast with prilled urea.

The nitrification inhibitors significantly retarded nitrification of both aqueous and prilled urea. PPDA reduced ammonia volatilization from 375 kg N/ha broadcast as urea, and hence losses to the atmosphere, which otherwise ranged from 13 to 33 kg N/ha.

Nitrapyrin or STC and KEtX increased yield and nitrogen uptake in both years when urea was injected in January. Nitrapyrin also increased yield and nitrogen uptake in 1985, but not in 1984, when urea was injected in March, whereas the STC and KEtX mixture was then either detrimental or ineffective. DCD increased yield and nitrogen uptake from a single dressing of broadoast urea only in 1985. PPDA increased yield and nitrogen uptake from a single broadcast dressing of urea in both years, but had little effect when applied with divided dressings.

In 1984 a divided broadcast dressing of ‘Nitro-Chalk’ gave the largest yield and nitrogen uptake, but in 1985 aqueous urea injected with nitrapyrin in January or without or with a nitrification inhibitor in Maroh and prilled urea broadcast as a divided dressing all gave a larger yield. Similarly, a single application was generally more effective as ‘Nitro-Chalk’ in 1984, but as urea in 1985.

A 28-month trial was carried out under extensive grazing conditions to examine the effects of giving water to Boran cattle once daily, once every 2 days, and once every 3 days, with cattle having ad libitum access to water serving as the control. In the dry season, the weight and condition of lactating cows given water every 3 days declined more rapidly than that of cows given water daily. Calving rates and birth weights were unaffected by treatments although when compared with cows given water ad libitum, birth weights were depressed by 2·5 kg in all treatments. Thirty steers showed no treatment differences in 28-month weights despite a depression in dry-matter intake in the dry season by animals given water every 3rd day. In contrast, 210-day weaning weights were significantly depressed by 9 kg when cattle drank water every 2 days and 14 kg when they drank every 3 days compared with calves given water daily. Total water consumed was depressed in all classes of stock by 5–10% under the 2-day regime and by 25–34% under the 3-day regime when compared with cattle given water daily. The results show that giving water every 3 days can be carried out indefinitely with all classes of stock with only minor effects on cattle productivity under the climatic conditions in which the trial was held. The management implications of giving water every 2 or 3 days to cattle under extensive, pastoralist and ranching conditions are discussed.

Sodium chlorite increased the degradability of fibre from a range of mature grass forages inoluding barley straw by 40–50 digestibility units when comparisons were made using ground (1 mm sieve) material incubated either in vitro with cellulase or in nylon bags in the rumen. However, when fed to sheep, chlorite-treated barley straw was digested to a similar degree to untreated straw (49 and 57% respectively), but intake was significantly reduced (385 and 790 g/day respectively). The poor in vivo utilization of chlorite-treated straw coincided with high proportions of propionic to acetic acid in the rumen (0·85, cf. 0·28 with untreated feed) and absence of rumen fungi. Rumen pH and ammonia concentrations were not significantly different between diets. When incubated in nylon bags in the rumen of animals fed the corresponding diet, both untreated and treated straw (< 1 mm) were well colonized with micro-organisms, as measured by cystine accumulation which showed peaks on the fibres after 24 and 72 h. While large numbers of fungal sporangia were observed after 24 h incubation on digesta from untreated forage, no fungi could be detected on the chlorite-treated material. Cystine accumulation on the untreated straw after 72 h was not associated with a secondary growth of fungi.

Although barley straw chaff, ground (< 1 mm) after treatment with chlorite, was highly degraded in nylon bags in the rumen and with cellulase in vitro, larger particles (1 cm) suspended in nylon bags in an animal fed chlorite-treated straw actually gained weight, probably due in part to the degree of microbial colonization.

Fourteen cow peas were tested for susceptibility to infestation and damage by Callosobruchus maculatus (F.) in the laboratory. IT81D-897 and Popse showed the lowest damage over a 3-month test period. 100-seed weight was not significantly correlated with seed damage.

The developmental period of G. maculatus was significantly longer in IT81D-897 and Popse than in other cow peas tested. Percentage adult emergence and fecundity of females were also lowest in these two cow peas.

Dissection data from 341 carcasses collected over a period of 7 years at the Institute of Food Research, Bristol (Large White, 138 entire males and 112 females; Pietrain, 41 entire males and 31 females; Iron Age (European Wild Pig × Tamworth), 8 entire males and 11 females) were used to examine the growth of muscle, fat and bone in joints relative to the corresponding total tissue in the side, and the growth of the fat depots relative to total side fat.

The musculature of Iron Age pigs was early maturing, as indicated by a particularly slow growth of pelvic limb and fast growth of neck and thorax muscles relative to total side muscle. As a consequence, Iron Age pigs had a lower percentage of pelvic limb and a higher percentage of neck and thorax muscles than the other breeds. Pietrains had proportionately the heaviest pelvic limb muscles, a result which was apparently independent of the overriding effect of maturity. However, considering the large difference in body shape (conformation) between Pietrain and Iron Age pigs, the differences in muscle weight distribution were small. Entire males had faster growing and heavier neck and thorax muscles than females. This was considered to be due to the effects of sex hormones. Entire males had proportionately less muscle in the pelvic limb.

Within carcass fat, the order of increasing growth rate relative to total side fat was intermuscular fat <; subcutaneous fat <; perirenal-retroperitoneal fat. Pietrain and Iron Age pigs had higher relative growth rates for subcutaneous fat and lower relative growth rates for intermuscular fat than Large Whites, an indication of earlier maturity in carcass fat development. This was reflected in Iron Age pigs, but not Pietrains, in a particularly heavy weight of subcutaneous fat and light weight of intermuscular fat. Within the subcutaneous and intermuscular fat depots, the highest allometric growth coefficients were generally observed in the forequarter. There were no consistent breed effects on the distribution of subcutaneous fat whereas, in the intermuscular fat depot, Iron Age pigs had less fat in the earlier-maturing thoracic limb, and lumbar and abdominal joint. At the same weight of total side fat (8·80 kg), entire male Pietrains and Large Whites had more intermuscular and less subcutaneous fat than females. There was no sex difference in fat partition in Iron Age pigs.

In all breeds, bone in the pelvic limb had the slowest relative growth. Similarly, the femur and the tibia-fibula were the two slowest growing bones of the four major limb bones examined. Otherwise, there was no consistent pattern of relative growth throughout the skeleton. Breed effects on relative growth within the skeleton and on bone distribution were small and considered to be of little commercial significance. Pietrains had the highest muscle: bone ratio in each of the four anatomical joints. Entire males and females had a similar relative growth and distribution of bones. Females had consistently higher muscle:bone ratios.

The precision of the capacitance probe in detecting herbage mass differences between treatments has been assessed on a cross section of field trials in Otago-Southland, New Zealand. Used thoughtfully, the probe appears at least as good as any other alternative. Corrected meter readings from the probe may be used directly for relative ranking of treatments although calibration is desirable for interpretation purposes, and becomes essential when swards of widely differing composition are to be related. Considerable overall time savings, especially in the laboratory, are possible in comparison with other methods.

Five experiments were carried out in two seasons which studied the effects of seed weight, seed rate and date of harvesting on yield of seed crops of Record (four experiments) and Maris Piper (one experiment) in Scotland. Small seed (35 g) produced more above-ground stems and tubers and higher seed yields at equal seed rates than large seed (105 g). Increasing seed rate with both seed weights increased yield of seed-size tubers. The value of the seed crop was measured as the number of ware hectares which could be replanted from the yield of 20–55 mm tubers and calculated using recommended seed rates (Ministry of Agriculture, Fisheries and Food, 1982). Small seed produced more replantable hectares than large seed at equal seed rates in all experiments with Record and increasing seed rate increased the number of replantable hectares. However, when seed retained for replanting at the same seed rate was taken into account, small seed produced more replantable hectares only when total yield reached approximately 40 t/ha. Seed yield was much higher in Maris Piper than in Record and effects of seed weight were small. Increasing seed rate increased the number of replantable ware hectares but the effect was much reduced after retention of seed for replanting.

The effect of pricing policy for seed and ware on returns to the seed grower was also established. The sale of seed (and ware tubers) at fixed prices per tonne produced lower returns than selling seed at varying prices per tonne in relation to tuber size and equivalent to a fixed ware cost per hectare planted especially where seed yields were high. Delaying harvesting increased sale value but crops reached 85–90% of the final value before many oversize tubers (> 55 mm) were found and large yields of such tubers from low seed rates produced lower returns than from increased seed rates.

The number of ware hectares produced per seed hectare (even net of seed retained for replanting) was high especially in Maris Piper. The results show that the area devoted to seed potato production in U.K. is much too high for the ware area and the significance for the future of seed production is discussed.

Soya bean variety Semmes failed to nodulate with a number of R.japonicum strains. Some of these were applied to the seed in a carrier based on Nile silt.

A three-strain composite in peat gave good nodulation and reasonable N fixation. Inoculation significantly outyielded 100 kg N/ha added as urea in three equal portions at sowing, 1 and 2 months after sowing. Plant dry matter, nodule dry matter, yield, yield components and seed protein were also significantly enhanced by inoculation.

Phosphorus applied at 50 and 100 kg P2O5/ha in combination with a starter dose of nitrogen (10 kg/ha) with inoculation both gave erratic and inconclusive results.

The effect of previous rotations maintained for 21 years on wheat and potatoes grown after 5 years of uniform cropping are described and discussed. Effects of length of ley in the rotation were detected in soil organic carbon, yield of wheat and yield of potatoes 6, 6 and 7 years respectively after the last ley was ploughed up. The effect of grazing the leys compared with mowing was detected in soil organic carbon and in yield of potatoes, and that of applying dung was detected in soil organic carbon and in yield of potatoes 12 and 13 years, respectively, after the last application.

The effects of drilling date (18 August–22 September) on the growth and yield of oil-seed rape (Brassica napus) was studied in a series of five experiments over three seasons. Autumn and winter growth of the crop, as measured by dry weight of tops and leaf area, was severely reduced by delayed drilling, especially if it was later than 10 September. However, during the spring and early summer the differences in crop weight due to drilling date declined and in four of the five experiments there were no detectable differences in seed yield between early- and late-sown crops. The yield decline in the fifth trial was small. Measurements of components of yield showed that later-sown crops had fewer pods per plant and slightly smaller seeds but apparently more seeds per pod. The practical significance and reasons for the recovery of late drilled crops from early poorer growth are discussed.

Cell walls from mature stems of three tropical grass species (Digitaria decumbens (pangola), Setaria anceps (cv. Kazangula) and sugar cane), and temperate barley straw, were analysed for lignin, carbohydrate, and the maj or acyl groups ferulate, ρ-coumarate and acetate. Samples were incubated in nylon bags in the rumen of sheep in a 4 x 4 latin-square design, and rates of disappearance of cellulose, hemicellulose, xylose, arabinose, ferulate, ρ-coumarate and acetate were determined during 60 h incubation. Interspecies differences in cell-wall chemistry appeared largely in the variable degree of acylation with p-coumaric acid (1·0–3·3%) and acetate (0·5–3·6%), and the high glucose concentration in the hemicellulose from pangola (17%) and Setaria (9%). Barley had much lower concentrations of these components than the tropical species. After 24 h incubation, losses of cellulose and acyl groups were greatest from pangola, whereas hemicellulose and its major components xylose and arabinose were degraded to the greatest degree from barley straw. Setaria cell-wall components were generally more resistant to degradation than the other species. No relationship was found between the concentration of any cell-wall constituent and degradability measurements. Nor were changes in microbial population, indicated by measuring the accumulation of cystine on the fibres, related to the rate or degree of degradation of any of the measured cell-wall constituents. Lignin was fractionated with alkali into insoluble and soluble fractions. The latter (25–50% of original lignin) gave high interspecies correlations with the degradability of total hemicellulose and its component monosaccharides. It was concluded that variability in the biodegradability of the cell walls was more likely due to in situ structural features, such as cross-linking between polymers, than to the concentration of any particular cell-wall constituent.