Deer farming commenced in New Zealand (NZ) in 1969, and since then the number of farmed deer has progressively increased, to reach 1·3 million in 1993 (Game Industry Board (GIB), personal communication). These comprise 85% European red deer (Cervus elaphus), with the remainder being composed of elk (Cervus elaphus canadensis), elk/red deer crossbreds, fallow deer (Dama dama) and small numbers of other species. Initially, deer were obtained from the capture of feral animals, introduced to NZ over 100 years ago, but in the last 10 years the increase has come from breeding on deer farms. The industry has a strategic marketing plan to coordinate all sectors in order to maintain profitability. This plan has been implemented and financed by the GIB, through the collection of compulsory levies on venison and velvet sales. With the formation of the GIB in 1984, the NZ Deer industry has been strongly export market-led, and thus differs from the NZ sheep and cattle industries, which developed with a production driven philosophy. Key aspects of the market-led approach have been to produce and market venison which is consistently tender and of low fat content, and at the carcass weight range and times required by the markets.

The effects of root and shoot characteristics on the lodging resistance of four cultivars of winter wheat were investigated by combining results from a field trial (set up at Manchester University's Experimental Grounds, Jodrell Bank, in mid-September 1991) with morphological and mechanical measurements on their stems and anchorage systems. Cultivars showed contrasting lodging resistance: Widgeon was most susceptible, followed by Galahad, Riband and Hereward which, alone, did not lodge. Lodging resistance was not related to the strength and stiffness of the stems, which were usually adequate to withstand the forces to which they were subjected. Most plants instead failed in their root system which rotated through the soil. Resistance was associated with short and light stems (and hence on the force applied to the plants by wind and gravity) and with high values of the anchorage strength of the root system (and hence on the force resisting lodging). Lodging occurred during grain filling when the ears were heaviest and when the soil was wet. The anchorage strength of a plant depended on two characteristics of the root system: the bending strength and the angle of spread of the basal coronal roots. Plants with stronger, more widely spread coronal roots produced larger soil cones during anchorage failure and resisted larger forces. Future breeding for lodging resistance, therefore, should continue to select for plants with shorter stems and with stiffer, more widely spread, coronal roots.

Two cereal cropping systems are described which, through the introduction of a leguminous intercrop, increased productivity, nitrogen output and ground cover of the systems in the absence of added nitrogen fertilizer. Nitrogen-fixing legumes were cultivated between rows of wheat or barley grown at low levels of soil nitrogen, and mostly under rainfed conditions, in Mexico between 1989 and 1992. None of the legumes tested reduced yields of the cereal crop in comparison to controls where cereal yields were in the range of 1–4 t/ha, while the extra total biomass from legumes in some cases more than doubled productivity. Different legume crops were tested to demonstrate the adaptability of the system to the varying needs of farmers. The intercropped legumes achieved dry biomass yields as high as 6·5 t/ha in the case of a sequentially cropped forage crop of hairy vetch, or 1·4 t/ha of dry beans plus 3·5 t/ha of green residue in the case of Vicia faba. Total biomass in the intercropped situation gave land equivalent ratios as high as 1·54. Light measurements inside the crop canopies indicated that the intercropped systems intercepted a higher proportion of the incident solar radiation than the cereal monocrop, presumably accounting for the large differences in total biomass produced. In addition, with leaf nitrogen levels of 3·8%, it is assumed that the intercropped legumes fixed considerably more nitrogen than was removed by the wheat crop. The potential of the system to stabilize erodible soils by increasing ground cover as well as by raising inputs of soil organic matteris discussed.

Sixteen common bean (Phaseolus vulgaris L.) cultivars with different life cycles and growth habits were intercropped with four maize cultivars, to evaluate the competitive ability of each yield component, following a methodology similar to that used for diallel crosses. The experiments were done in 1991 at two sites in Brazil. The intercropping combinations were evaluated using an 8 × 8 quadratic lattice design with three replications. Two other experiments were done on monocultures, using a randomized complete block design with three replications. The variable considered was ‘maize equivalent yield’, obtained by adjusting for the price difference between the species. The method used showed that the differences in performance of the many intercropped combinations can be explained by ‘general complementing ability’ (gĉa) of each cultivar, since there was no significant effect of ‘specific complementing ability’ (sĉa). The best maize cultivars to be intercropped with common bean (indicated by high gĉa values) were BR–201 and C–525, which produced high grain yields when intercropped without detrimental effects on legume yields. FT–84–292, Carioca 300V and ESAL506 were the common bean cultivars with the highest yields when intercropped, which was also reflected in their good performance in monoculture. Significant cultivar × location interactions occurred only in monocultures, supporting the belief that intercropping is a more stable cropping system.

Maize (Zea mays L.) and common bean (Phaseolus vulgaris L.) were each sown at four plant densities, including zero, in a bivariate factorial design at Kiboko Rangeland Research Station, Kenya during the long and short rains of 1990. The design gave nine intercrops with different proportions of maize and beans, and six sole crops, three of maize and three of beans. Seed yields in both the sole crops were not significantly affected by plant density, so the mean yield was used to calculate the Land Equivalent Ratio (LER), which averaged 1·09 in the long rains but only 0·87 in the short rains. These low values were apparently due to the fact that beans failed to nodulate and fix nitrogen in the study area. The difference in LER between seasons was probably caused by differences in the amount and distribution of rain in relation to crop growth. Maize was more competitive than bean, each maize plant being equivalent to between 0·7 and 3·4 bean plants depending upon the treatment and the season.

A model was developed to assess the suitability of land in England and Wales for growing newly developed genotypes of autumn-sown determinate white lupins. The model used soil pH, the number of degree-days accumulated for mainstem leaf production before the apical meristem of the mainstem became floral, and the number of machinery work days in autumn. Interactions between these three components were used to set thresholds to determine land suitability within 5 × 5 km grid squares of the National Soil Map.

Of the potential 13·75 Mha of arable land in England and Wales, a total of 7·54 Mha are well or moderately suited to growing these lupin genotypes. This is equivalent to c. 2 Mha of land within the arable rotation each year. It was estimated that, because of low soil pH, lupins would be the preferred legume on 0·3 Mha out of this 2 Mha. The model was also used to assess the risk of soil acidification and nitrate leaching following mineralization of lupin residues. This exercise indicated that there was little risk of either on much of the land suited to lupins.

In 12 field experiments in England (1985, 1991 and 1992), on soils infested with potato pale cystnematode (Globodera pallida), oxamyl increased yields of susceptible and partially-resistant potatoes and lessened nematode multiplication at some sites but not others. Attempts to explain these site differences were unsuccessful. In a heavily infested peaty loam, large amounts of aldicarb or oxamyl, smaller amounts of both conjointly or 6·8 kg oxamyl/ha incorporated in the top 10 cm of the soil were needed to prevent G. pallida multiplication on susceptible Wilja potatoes. In three experiments, 1,3-dichloropropene at 250 or 225 1/ha increased tuber yields more than oxamyl did but had little or no effect on G. pallida multiplication. Ethoprophos at 11 kg/ha or fosthiezate at 4 kg/ha lessened G. pallida multiplication on Désirée potatoes in a silt loam soil but not in a peaty loam soil.

The multiplication of G. pallida was reliably controlled in ten experiments by partially-resistant Morag or Santé potatoes. Soil population densities of G. pallida were greatly decreased by one or two crops of Cara potatoes uprooted when the first female nematodes were visible on the roots.

It is concluded that granular nematicides and 1,3-dichloropropene are best employed to lessen injury to susceptible and partially-resistant potatoes and that G. pallida increase is best controlled by partially-resistant potatoes protected by a nematicide. Soil infestation levels can be decreased rapidly by soil fumigation or trap cropping with Cara potatoes.

The response of late-sown mustard (Brassica juncea L.) to four rates of irrigation (ratio of irrigation depth to cumulative pan evaporation, ID:CPE = 0·2, 0·4, 0·6 and 0·8) and nitrogen (0, 30, 60 and 90 kg/ha) was investigated at Haryana Agricultural University, India, in the winter seasons of 1986/87 and 1987/88. Increases in the amounts of water and N fertilizer applied increased leaf water potential, stomatal conductance, light absorption, leaf area index, seed yield and evapotranspiration and decreased canopy temperature. Water-use efficiency was highest for the 0·4 ID:CPE irrigation treatment in both seasons, and for the 60 kg N/ha N treatment in 1986/87 and the 90 kg N/ha treatment in 1987/88. The combination of 0·6 ID:CPE with 60 kg N/ha gave a significantly higher seed yield than lower rates and equalled that from the highest irrigation and N treatment combinations. The amount of water used by the mustard crop decreased with increasing soil depth irrespective of treatment. In the deeper soil layers, the percentage of total moisture use was greater under less irrigated than under more frequently irrigated plots. Leaf area index showed a significant positive linear relationship with evapotranspiration and light absorption and a negative linear relationship with canopy temperature. Seed yield was linearly related to leaf area index and light absorption coefficient.

The effects of inoculation by Ascochyta fabae Speg. on growth and light interception in field bean (Vicia faba L.) were studied. Measurements were made in a field trial using cv. Ticol, a cultivar vulnerable to this disease during early vegetative growth and at the beginning of the flowering stage. Infection reduced leaf area duration, light interception and dry matter yield of energy (light use efficiency) and, consequently, the dry matter production of the crop. Reductions in seed yield ranged from 12 to 30% compared with a prophylactic fungicide treatment.

An experiment was conducted to investigate the effects of planting pigeonpea in May, June or July at Mokwa and June or July at Shika and Kano, Nigeria at population densities of 18·5×103, 27·8×103, 55·5×103, 111×103, 222×103 and 444×103 plants/ha on dry matter (DM) and seed yields of cultivars Local, UQ50, 3D8103, 3D8104, 3D8111 and 3D8112 in the 1974/75 season. Planting in May had no above-ground DM yield advantage over planting in June at Mokwa. Planting in June gave higher yields than planting in July irrespective of site, except for the short, early maturing, soya-type cultivar 3D8103 at Shika. Cultivar responses to density were inconsistent between sites and also between dates at Shika and Kano. Cultivars Local, UQ50 and 3D8104 showed the highest DM yield at all sites. Leaf DM yield tended to decline as planting was delayed but was highest at densities of 111×103 or 222×103 plants/ha for May and June-planted cultivars Local, UQ50, 3D8104 and 3D8112, which showed potential as feed supplements for poultry. Reasons were advanced for the variability in pod yield responses to planting date and density between the different pigeonpea cultivars. Root DM yields were proportional to above-ground DM yield but, over all cultivars, root yield was unaffected by planting date at Shika.

Seed yield was highest from the June sowing, cv. 3D8104 was the most productive and the optimum densities were 27·8×103 plants/ha for the larger-sized cultivars Local and UQ50, 55·5×103 plants/ha for the medium-sized cultivars 3D8104, 3D8111 and 3D8112, and 444×10 3 for cv. 3D8103. A complementary study over 13 years showed that the seed yield of intermediate and late maturing pigeonpeas was strongly and linearly related to total annual rainfall.

Ferrous iron is oxidized and precipitated as iron ochre in field drains. In drainage waters taken from an ochre-producing site near Aberdeen, Scotland in 1987, iron deposition was inhibited by the addition of humic and fulvic acids, which form complexes with Fe(II). The inhibition was dependent on the concentrations of soluble humic materials and the proportion of Fe complexed. Iron deposition in the presence of humic substances is discussed in relation to the amount of the cation which is complexed and its oxidation state.

In field drainage waters, Fe(II) can be oxidized to Fe(III), which is precipitated as iron ochre. At a farm near Aberdeen, Scotland, ochre is precipitated both chemically and biologically. The precipitation was delayed using the antibiotic D-threo-chloramphenicol and Cu(II) ions. Iron deposition was delayed on glass slides coated with copper filings. It is suggested that the incorporation and slow release of substances which inhibit ochre formation, from drainage pipe material, would be a valuable method of controlling the ochre problem.

In three separate experiments, groups of four, three and six mature, rumen-cannulated Simmental cows were fed diets designed to supply different quantities of energy (E) and nitrogen (N) to the rumen microbes. Experiment 1 (straw plus concentrate plus urea) had balanced E and N supplies; Expt 2 (hay and four levels of soyabean meal) had different sub-optimum N levels at the same intake as Expt 1; and Expt 3 (hay plus maize plus two levels of urea) reproduced the N shortage in Expt 2 at a higher level of intake.

The amount of total N excreted in the urine (TUN) was 574 mg/kg LW0·75 in Expt 1 and 420 mg/kg LW0·75 of this N was excreted as total purine nitrogen (TPN). In Expt 2, TUN increased significantly (P < 0·05) with increasing soyabean levels; TPN also increased, reaching the level observed in Expt 1 when soyabean meal supplementation was highest. In Expt 3, TUN and TPN increased with increasing dietary urea concentrations; TUN and TPN were always higher than in Expts 1 and 2.

Estimated microbial nitrogen supply (EMNS, based on TPN) was always considerably lower than estimates based on fermentable non-protein OM and crude protein (EMNR-EN) or an assumed yield of microbial N per kg OM apparently digested in the rumen (EMNR-OM). Regression analyses of EMNS on EMNR-EN, EMNR-OM or OM intake had moderate r2 values (0·76, 0·65 and 0·62 respectively) but the constant terms were significantly different from zero. The regressions of EMNR-EN and EMNR-OM on TPN gave angular coefficients of 15·81 and 11·47 respectively.

The correlation between rumen liquid parameters (total count, bacterial DM, ATP and nitrogen) and OM intake, EMNS or EMNR increased with sampling time (from 09.00 to 16.00 h). The EMNR-OM produced correlation coefficients similar to those obtained with OM intake; these correlations were numerically higher than those obtained with EMNS or EMNR-EN.

This study was conducted in the central highlands of Ethiopia during 1990–92 to examine the effects of diet and partial suckling on lactation and reproductive performance of Boran (Bos indicus) cows. Primiparous Boran cows were allocated to dietary supplementation or no supplementation with either milking or partial suckling based on body weight at calving. All cows received grass hay ad libitum and the supplemented groups were provided with additional concentrate feed which supplied 222 g/kg DM crude protein and 10 MJ/kg DM energy. Calves were weaned at 8 weeks of age. Mean (±S.E.) dam calving and calf birth weights were 314±11·4 and 25±0·6 kg. Body weights at first postpartum oestrus and at conception were not affected by suckling. Supplemented cows however, were heavier at first oestrus (P = 0·06) and at conception (P < 0·01) than non-supplemented cows. Lactation length was longer (P < 0·01) and mean daily milk yield higher (P < 0·001) in suckled than in milked cows. Diet, however, did not influence either lactation length or daily milk yield. In suckled cows, mean daily milk yield declined sharply after weaning (week 9) and was lower by 38 and 43% of week 8 production in the supplemented and non-supplemented groups, respectively. The overall mean lactation yield was 212·4±64·6 litres; with a significant (P < 0·05) diet × suckling interaction effect. Concentrations of milk fat, total protein and total solids were not affected by either diet or suckling treatment. The postpartum anoestrus interval was longer (P < 0·01) in non-supplemented than in supplemented cows, but did not differ between suckled and milked cows. The percentage of cows cycling by 150 days postpartum was higher (P < 0·05) in supplemented than in nonsupplemented and in milked than in suckled (P > 0·05) cows. By this interval, a higher (P < 0·05) percentage of supplemented-milked (90%) cows cycled than in the other three treatment groups (48·5%). Pregnancy from the first insemination ranged from 45·5 to 63·6% in the four treatment groups. It was concluded that although partial suckling extended the postpartum anoestrus interval, lactation length and milk yield were improved. The negative effects of partial suckling on postpartum reproduction could be overcome with the appropriate dietary supplementation. The economic tradeoff between dietary supplementation, milk yield and reproduction has to be determined in partially suckled cows.

Experiments were carried out in 1992 with ten male calves, 4 weeks old initially, on a milk diet. Five calves received 80 mg/head virginiamycin (a feed antibiotic) daily for about 14 weeks. Virginiamycin significantly (P < 0·05) increased weight gains (122±2 kg ν. 114±2 kg), digestibility of ash, serum iron and haemoglobin. The feed intake per 1 kg of gain was non-significantly lowered in the virginiamycin group. The phagocytic activity of granulocytes in blood samples of treated calves was slightly increased with a concomitant decrease in the concentration of immunoglobulins. Meat of virginiamycin-fed calves tended to be somewhat darker, to contain more K, Na and Fe and to have a higher pH 24 h post mortem. There were no major differences in other qualitative characteristics of meat between the groups.

Over 5 years (1987–91), the progeny of rams selected for fast (Low T-half) or slow (High T-half) glucose clearance after an intravenous glucose tolerance test, differed significantly in glucose tolerance. In comparison with an unselected control, the line differences were mainly in the direction of Low T-half. They appear to have arisen during the establishment period, with little evidence of enhanced divergence over the four subsequent years of continued selection (heritability 0·10±0·03). The Low line had higher plasma insulin concentrations during the glucose tolerance test than the High line. Basal plasma concentrations of glucose were lower, and urea higher in the Low than the High line. In addition, carcasses of Low line ram progeny had more subcutaneous fat at the same carcass weight than High line carcasses (11% higher GR in the final year of the experiment). Selection of sheep for glucose clearance appeared to be associated with differential partitioning of nutrients into adipose tissue, the pooled genetic correlation between T-half and GR being −0·28±0·13.

Experiments were conducted to determine the effects of zinc (Zn) supplementation on the performance and mineral metabolism of lambs fed forage-based diets containing 15–23 mg Zn/kg. In Expt 1, 20 lambs were fed a good-quality orchardgrass (21·4 mg Zn/kg) or a low-quality tall fescue (14·7 mg Zn/kg) hay and supplemental Zn (as ZnO) at 0 or 30 mg/day in a 2 x 2 factorial arrangement of treatments. Forage was fed ad libitum and all lambs received 92 g dry matter/day of a corn-based supplement which served as the carrier of the supplemental Zn. Lambs fed orchardgrass hay had a greater (P < 0·01) dry matter intake and average daily gain for the 42-day study. Zinc supplementation did not affect performance of lambs fed tall fescue but tended to improve performance in those fed orchardgrass hay. At the end of the 42-day growth phase, lambs were placed in metabolism crates for a 7-day total collection of urine and faeces. Supplemental Zn increased intake (P <0·01) and faecal excretion (P <0·01) of Zn. Absorbed Zn was greater (P < 0·05) for lambs fed supplemental Zn. There was a tendency for a forage × Zn interaction (P < 0·10) for urinary Zn excretion and retention. Urinary Zn excretion was highest in lambs fed tall fescue hay supplemented with Zn. In Expt 2, 24 lambs were fed diets consisting of ad libitum chopped tall fescue hay (23 mg Zn/kg) and 176 g/day of a corn and mineral supplement which served as the carrier of the Zn treatments. Treatments were no supplemental Zn or 30 mg/day supplemental Zn as ZnO, ZnSO4 or Zn methionine. Zinc oxide and ZnSO4 supplementation increased average daily gain (P < 0·10) and decreased feed/gain (P < 0·10) for the 56-day study when compared to control and Zn methionine-supplemented lambs.