The oil content of a number of introduced and local varieties was determined using three nuclear magnetic resonance oil analysers at different centres and compared with results from conventional solvent extraction. Differences were evident between the three centres and between the techniques but in both cases the rankings were similar.

Twenty cultivars of P. vulgaris differing in growth habit, and inoculated with an efficient strain of R. phaseoli, were sampled weekly in the period 22—99 days after planting. Acetylene reduction and specific nodule activity were similar to or better than those reported for other grain legumes, and were higher than achieved by a soya-bean cultivar. Though the period of active fixation was limited, nitrogen gains estimated at 25—30 kg/ha/growing cycle were obtained. Climbing beans were superior to bush beans in acetylene reduction and specific nodule activity, but differed little in nodule development. Two varieties, Cargamanto and Sangretoro, were outstanding in fixation. Differences between varieties in nodule to root ratio, and in rate of N accumulation in the leaves were shown. Both groups of plants stored appreciable starch in the stem after flowering. The results are related to the need for N fertilization in Latin America.

Differences between sites accounted for a large proportion of the variation in the oil percentage of cotton seed from variety and agronomic trials conducted in Northern Nigeria but were not consistent between seasons. Reduced oil percentages from the drier areas of the north and from later sowings suggested that length of season is an important factor but insect attack and differences in the amounts of nitrogen, potash and boron applied to the soil also contributed to the variation. Application of insecticide, potash and boron increased and nitrogen decreased oil percentages. The latter effect usually resulted from an increase in seed size without a corresponding increase in oil content. The variation in the oil percentages of commercial varieties derived from the same Nigerian Allen stock and the relatively small interactions between varieties and environments suggested that this character might be improved by selection.

Heat-tolerance tests and observations on coat shedding were made on Santa Gertrudis and Hereford heifers of similar age in the warm humid climate of Fiji.

Coat shedding (which is influenced by day length) was normal in the locally bred, smooth-coated Santa Gertrudis whose heat-tolerance was good. However, the Herefords, which had come from New Zealand and had very woolly coats failed to shed properly and suffered serious heat stress.

Clipping and the use of a close-fitting jute rug demonstrated the specially high heatretaining properties of a thick natural coat of cattle hair; also the special need to select animals of low coat score for the very humid tropics.

Setts of white yam (cv. Ogojo) each weighing 225 g were planted in mid·February. They were double-harvested, first in early August, early September or early October, and second in early November. The control was single-harvested in early November. The later the time of the first harvest, the greater the first-harvest yield and the higher the percentage of mature and marketable tubers. Delaying the first harvest, however, led to decreasing yields from the second harvest. Double harvesting never gave a significantly higher yield than that obtained from a single harvest. When the first harvest was taken in September, the combined yield from double harvesting was significantly lower than that of the single November harvest. In a study of the effect of sowing date on yield, late planting (April) resulted in lower first harvest and total yields than early (February) planting, but the second-harvest yield was the same. Supplementary watering of early yam plantings did not markedly accelerate emergence or increase yield.

Two gene markers were observed among cowpea breeding lines in Ibadan, Nigeria. One is the swollen stem base which is due to a larger quantity of phloem parenchyma in the bottom part of the stem below the first primary leaf than in the normal stem. It is inherited as a simple dominant trait and the symbol Sw is suggested. The other is the hastate-leaf which is expressed as extremely narrow trifoliate compared with the normal. It is inherited as a simple dominant trait and the symbol Ha is suggested. Dominance may not be complete in both cases as variable expressions of the marker genes were observed in F2. The effects of the marker genes on yield and other characters are currently being investigated.

Cassia acutifolia Del., known in the Sudan as ‘Senna Makka’ and in commerce as ‘Alexandrian Senna’ (Tothill, 1948), is indigenous to the Sudan and grows wild in the Northern and Central Provinces. It is used locally as a laxative and itsactive ingredient senoside is extracted for pharmaceutical purposes in England, U.S.A. and Germany. The Sudan has been exporting pods and leaves of Senna for many years and the crop has been steadily growing in economic importance. The exported produce is obtained from wild or cultivated Senna plants. Recently a breeding programme has been initiated to provide improved varieties that can both meet the growers’ need for high yield and satisfy the market's demand for uniform high quality produce. Before a proper plant breeding programme can be established, the mode of reproduction must be known since crop breeding procedures are largely determined by the reproductive system. This paper reports on studies made to determine the breeding system in Alexandrian Senna.

An experiment is described in which plots of a silt loam soil and a clay soil were compacted by ploughing when the soil was ‘wet’ or ‘dry’. Further plots were thoroughly loosened by hand digging. These treatments resulted in a wider range of soil physical conditions than had been obtained in a previous experiment.

A 2-year ley of Italian ryegrass was grown on the plots and was harvested twice in each year. Marked effects on crop yield were found at the first harvest but relative effects at subsequent harvests were much smaller. Yield responses to differences in soil physical conditions depended on stage of crop, levels of applied nitrogen fertilizer, inherent chemical fertility of the soil and distribution of rainfall during the growing season.

In group and individual feeding experiments of 98 days duration, a total of 96 Large White x Landrace 9-week-old pigs were fed diets (containing 0–09 mg selenium/kg) based on 85% of barley (containing 3 mg δ-α-tocopherol/kg), which had been stored aerobically for 1 year, with 0 (basal), 10, 20, 40, 80 or 160 mg/kg of synthetic δ-α-tocopherol added. In both experiments the tocopherol supplementation significantly improved growth rates over those obtained from the basal diet. Serum creatine phosphokinase and aspartate aminotransferase activities were not significantly affected.

The digestibility of protein of mixed whole rumen bacterial cells and Streptococcus bovis were determined in Bos bubalis and goats. The bacterial cells were labelled either with 35S or 14C in vitro incubation and were injected in a single dose into the rumen after protecting by formaldehyde treatment. Faeces were collected for 6 consecutive days and radioactivity excreted in the faeces was measured. The digestibility of bacterial protein ranged from 81·7 to 96·8% in both the species.

In a glasshouse experiment, fertilizer potassium and magnesium were applied in various amounts to 20 soils differing in the proportion of exchangeable potassium to the sum of the three exchangeable cations, potassium, calcium and magnesium. Maize, cv. Ganga-5, was grown as the test crop.

In soils where the exchangeable cation ratio (K/Σ (K + Mg + Ca), in equivalents) was less than 0·025, potassium fertilizer significantly increased the dry-matter yield of maize. In soils where this ratio was between 0·026 and 0·05, application of potassium fertilizer was beneficial only up to the intermediate amount of 11 mg K/kg soil. Beyond this amount of application, addition of magnesium was necessary to increase yields. In soils where this ratio exceeded 0·05, potassium fertilizer reduced yields.

An optimum ratio of exchangeable calcium, magnesium and potassium appears more important than their absolute amount. Magnesium application to high-potassium soils improved the cation equivalent ratio within the plant and the dry-matter yield.

In two experiments, 192 individually penned pigs were given diets containing 900 g barley/kg together with either 100 g dried microbial cells (DMC)/kg or 100 g white fish meal (WFM)/kg, and grown from 23 to 60 kg live weight. In Expt 1 rationing was by live weight and there was no difference between diets for feed used or live weight gained. In Expt 2, pigs were rationed by time and those fed diet DMC grew 15 g/day slower than those fed diet WFM, and their carcasses were of lower specific gravity.

Eight cultivars of peas (Pisum sativum L.) were evaluated for six traits in a diallel experiment using regression coefficients, correlations and combining ability estimates. Regression coefficient was high, indicating large additive effects for 100-grain weight. Yield was significantly and positively correlated with plant height, number of pods per plant and 100-grain weight, indicating that selection for either of these would result in higher yield. The best index of yield among the traits studied was number of pods per plant. Significant general combining ability (GCA) variances and specific combining ability (SCA) variances were observed. GCA variances were larger than SCA variances except for yield, suggesting predominance of additive gene effects.

Arginase (EC 3.5.3.1) catalyses the conversion of arginine to ornithine and urea, and is a key enzyme of the urea cycle. The enzyme is present in high activity in various mammalian red cells (Nishibe, 1973, 1974; Owczarczyk & Barej, 1975) and inherited arginase deficiencies have been found in two primate species (Shih et al. 1972; Terheggen, Lavinha & Colombo, 1972). The present paper describes an inherited arginase deficiency in the erythrocytes of certain sheep.

Few problems have been reported with the use of the isotope dilution technique for measuring volatile fatty acid (VFA) production in the rumen of sheep. However, early studies carried out in this laboratory, using a standard technique (Leng & Leonard, 1965) showed serious limitations associated with losses of activity from the infusates. Subsequent inquiries suggested that other laboratories had experienced similar problems (J. D. Sutton, National Institute for Research in Dairying, Shinfield, and D. E. Beever, Grassland Research Institute, Hurley, personal communication). When solutions of [U-14C]Na acetate, [l·14C]Na propionate and [l·14C]Na butyrate obtained from the Radiochemical Centre, Amersham, were each diluted with deionized water to provide 0·5 μtCi μtmol/ml (hereafter designated 14Ac, 14Pr and 14Bu respectively) and left to stand at room temperature for 6 h, losses of activity of C, 15 and 3% respectively were found.

The quantity of seed ingested and excreted by penned cattle from offerings of freshly cut kikuyu grass (Pennisetum clandestinum cv. Whittet) was measured during the autumn at Grafton, N.S.W. A mean 101·6 g of whole seed was ingested per head per day, of which 22·9% was excreted. During 18 weeks, seedlings emerged from every dung pat formed from collected faeces. The number of seedlings represented 3·45% of the whole seed ingested. The loss of covering structures from the seed during passage through the alimentary tract apparently reduced the 21–day germinability.