Early-weaned lambs were penned indoors for 6 weeks and individually fed to appetite on cold-stored ryegrass (Lolium perenne) or indigenous Agrostis-Festuca herbage of differing maturity. In another experiment similar lambs grazed for 12 weeks on swards of perennial ryegrass or Agrostis-Festuca. Live-weight gain (LWG), herbage organic-matter intake (OMI) and digestibility (OMD) were measured. In the indoor experiment ryegrass was 4–6 percentage units higher in OMD than was Agrostis-Festuca;first harvests were superior to later harvests by the same amount. The intake of ryegrass was 22% greater than that of Agrostis-Festuca. The correlation between OMI/W'73 and herbage cell-wall constituents was —0·80, and that between OMI/W'3 and OMD was 0·78. OMI/W0·73 increased progressively up to about 13 weeks of age.

LWG was higher on ryegrass than on Agrostis-Festuca; and LWG on the early harvests of each herbage type exceeded those on the later harvests. LWG was significantly correlated with the intake of digested organic matter (DOMI) (r = 0·85).

In the grazing experiment, OMD, OMI and LWG were all lower than in the indoor experiment. LWG on ryegrass was again superior to that on Agrostis-Festuca, and the difference was partly explained by the relationship between DOMI and LWG which had been established indoors.

These results suggest that the increase in the growth rates of hill lambs consequent on the improvement of indigenous Agrostis-Festucaswards would be less than that due to the provision of sown pastures of perennial ryegrass.

The total body water (TBW), its distribution and water turnover were measured in native fat-tailed Awassi sheep, a breed well adapted to desert conditions, and in imported German Mutton Merino (GMM) sheep, a breed that evolved in a temperate climate, under semi-arid conditions.

TBW (tritiated water space;TOH space), extracellular fluid volume (SCN-space) and plasma volume (T·1824 space) were measured during the summer while these sheep grazed natural pasture that remained as dried stem-cured hay and in the winter while they grazed lush natural pasture. No differences were found between the breeds in any of the measurements in both seasons. Within both breeds, the percentage TOH and SCN-spaces were larger in the summer whereas the percentage T·1824 space remained the same.

TBW and water turnover were measured in these breeds in eight trials while the sheep grazed native pasture in the autumn, winter and spring, shrubs in the winter and legumes in the summer. Water and shade were freely and easily accessible throughout the grazing period. The TBW was found to be consistently lower in the Awassi, indicating a higher energy reserve. The water turnover in 1/24 h/kg wt.0·82 was found to be higher in the GMM in all trials; the differences ranged between 3 and 28%. However, in only two out of the eight trials were the differences significant. Thus, the water turnoverwas only slightly lower in the Awassi although this breed evolved under Middle Eastern arid and semi-arid regions.

The total body water (TBW) and water turnover of fat-tailed Awassi ewes, a dairy breed well adapted to desert conditions, and of German Mutton Merino (GMM) ewes, a mutton breed that evolved in a temperate climate, were measured during the 3rd, 4th and 5th months of pregnancy and during the 1st month of lactation. Measurements were taken under grazing conditions with unrestricted water in a semi-arid region.

Both breeds of sheep lost weight during this period. The percentage of TBW increased, especially during the 5th month of pregnancy when the GMM increased their TBW by 5·2% and the Awassi by 1·0%. It was concluded that the nutritive intake was not sufficient to supply the increased energy demands and that the ewes were mobilizing body solids, the GMM at a faster rate.

The GMM ewes turned over about 20% more water per kg wt.0·82 during pregnancy and lactation than did the Awassi ewes. There was little difference in water turnover between the control and pregnant sheep within either breed during gestation. During lactation the experimental Awassi increased their water turnover by 29% over the control Awassi and the experimental GMM increased their water turnover by 26% over the control GMM. In both breeds the increase in water turnover during lactation was smaller than that found in other lactating semi-arid ruminants and the increase in water turnover during pregnancy and lactation was smaller than that recommended by the Agricultural Research Council (1965).

Three herbicides, Treflan, Basagran and Avadex BW and three pesticides, Metasystox 55, Nicotine and Hostathion stimulated the growth of Fusarium solanif. sp. phaseoli in culture and increased the virulence of this pathogen on Phaseolus vulgaris. The implications of these results to the chemical treatment of this crop are discussed.

A small-plot experiment was made to assess the influence on dry-matter output from grass of a wide range of fertilizer nitrogen and defoliation interval treatments. There were five defoliation treatments, 22, 28, 45, 75 and 112-day regrowth intervalsroughout the growing season each at six levels of nitrogen application, ranging by 300 kg increments from 0 to 1500 kg/ha/year.

There was a marked interaction effect between treatments; a positive dry-matter response was maintained to a higher level of applied nitrogen with more frequent defoliation. In 2 years out of 3 maximum dry-matter yield was produced under a 75·day defoliation interval although the mean yield advantage over a 45-day defoliation system was only 11%. Mean yield of digestible dry matter appeared to reach a maximum under a 45·day defoliation interval at 600 kg N/ha but at the lower levels of N the maximum yield was reached at the longest growth interval.

Seasonal response to nitrogen under the 22–day and 28–day defoliation systems measured as the increase in yield resulting from increased N at each cutting date reached its peak in July–August. Application for these short growth periods early and late in the growing season appeared to be a relatively inefficient use of nitrogen.

The less frequently the sward was harvested and the higher the nitrogen application the greater was the reduction in ground cover as estimated by eye at the end of the growing season, this reached an estimated 25% reduction under 112·day defoliation at 300 kg N/ha/year.

In relation to published figures nitrate content of herbage did not reach dangerous levels until nitrogen application reached levels beyond those at which maximum dry·matter yield was achieved.

A simple device for recording seedling emergence force was developed. In this device, the relationship between the bending moment and displacement of the free end of a cantilever beam is used to compute seedling emergence force. The growing seedling is forced to push the free end of the beam upwards and the displacement of the free end is recorded with a pointer on smoked paper tightly wrapped on a revolving clock drum.

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.

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.

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.

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 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.

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.