Studies on 59 first four completed lactations of 37 imported Jersey cattle in Western Nigeria showed that their mean lactation length (248·4 days) and average milk yield (1257·4 kg) were inferior to those of their counterparts in other tropical countries. Lactation length following the birth of female calves was longer and milk production greater than those subsequent to male births but the differences were small (P > 0·05). Peak milk production was reached at the third lactation. Influence of season of calving on lactation length was slight; mean milk yield was significantly highest (P < 0·05) among October-December calvers, while the July-December period appeared to be more propitious for milk production. The regression coefficients of lactation length and milk yield on age of dam at calving were negative and unimpressive (P > 0·05), being −2·108 ± 2·661 and −19·106 ± 17·130 respectively. Analysis of variance for weight of milk with lactation length as a covariate revealed that although lactation length was a major (P < 0·001) determinant of milk production, both the period of calving and lactation number had recognizable bearing on milk yield. All interaction effects were trivial (P > 0·05). The period of study was 1968–74.

Grain yields of 14 spring oat varieties grown at two levels of nitrogen in three seasons at two locations were compared. A genotype × environment analysis demonstrated that the more recent varieties not only had higher yields but also were better adapted to high-yielding environments. Modern varieties demonstrated a yield improvement of 30% over the older varieties. Examination of components of yield by a series of simple correlations indicated that improvement in varieties by breeding has been associated with shortened straw and higher harvest indices. Within varieties, 1000-grain weight was the most stable character and harvest index the character which varied most consistently with variations in grain yield.

Using continuous infusion techniques the entry rate of linoleic acid and its contribution to carbon dioxide production has been studied in fed and fasted sheep. The entry rate of linoleic acid in fasted sheep (0·052 mg/min/kg) was considerably less than that of stearic acid (0·432 mg/min/kg), and the percentage of total carbon dioxide production derived from the oxidation of linoleic acid (0·4%) was also markedly less than that from stearic acid (10·13%).

On starvation there was a preferential mobilization of palmitic, stearic and oleic acids relative to linoleic acid.

The infused 14C-labelled linoleic acid was initially incorporated into plasma phospholipids, with maximal radioactivity at about 1 day post-infusion, and subsequently into plasma cholesteryl esters with a maximum at 2 days post-infusion. The incorporation of 14C-labelled stearic acid into plasma phospholipids was only 25–30% that of linoleic acid, with negligible incorporation into cholesteryl esters.

Possible explanations for ruminant animals being able to exist on a very low intake of linoleic acid are discussed. In essence, there is a discrimination against the use of linoleic acid as an energy source, but the mechanisms involved do not appear to be unique to ruminant animals.

Ruminants have extremely low concentrations of polyunsaturated acids in their adipose tissue as a result of hydrogenation of dietary lipids by microbes in the rumen. The possible association between intake of ruminant products high in ‘saturated’ lipids and the incidence of atherosclerosis in man has stimulated research on procedures for altering the fatty acid composition of ruminant tissue lipids. Vegetable oils, emulsified with a protein, spray-dried, and treated with formaldehyde, have been found to be protected from hydrolysis and hydrogenation in the rumen (Cook et al. 1970; Scott, Cook & Mills, 1971). Their subsequent digestion in the small intestine, and absorption of the fatty acids by the animal, results in tissue lipids high in linoleic acid (Faichney et al. 1972; Faichney, Scott & Cook, 1973; Cook et al. 1972; Garrett et al. 1976).

Experiments were made to assess the nutritive value of expeller-proeessed mustard cake (MS) for egg-type and meat-type chicks. Eight samples of MS on average contained 37·2% crude protein, 27·5% true protein, 12·6% available carbohydrate and 2·09 % tannins. The average metabolizable energy content (ME) of eight samples of MS for egg-type and meat-type chicks were 2350 and 2300 kcal/kg respectively. MS in the diet replacing groundnut cake (GN) which formed 30–32 % of the control diets was found to have no effect on growth rate of the chicks of either breed although there was thyroid enlargement. MS was also found not to affect the body composition of the chicks.

Two methods of storing pollen of the dihaploid-inducing Dutch (Wageningen) Solatum phureja clone, IVP 48, are described. Pollination results showed that the functional fertility of one type of stored pollen is similar to that of fresh pollen when used in dihaploid induction crosses on tetraploid potatoes. No obvious relationship was found between the in vitro germination of the pollen samples and their functional fertilities in dihaploid induction crosses.

Sugar beet bolting in the root crop was studied during nine growing seasons, under the extreme climatic conditions in which the autumn-sown crop grows in Southern Spain.

Bolting is positively correlated with the number of days with minimum air temperatures ranging from 2 to 8 °C or with the number of days with mean temperatures between 8 °C and 13 °C.

The occurrence of bolting is also affected by rainfall distribution in so far as it determines the date of seedling emergence.

When high rates of fertilizer N are applied to grass in an area of low rainfall, considerable amounts may be lost to drainage in the subsequent winter if the N is not fully utilized owing to dry soil conditions during the growing season (Garwood & Tyson, 1973). The data now presented were obtained from the lysimeters described in that paper. The soil is a sandy loam, overlying chalk. The swards of perennial ryegrass (Lolium perenne cv. S. 23) were cut four times each year. Two rates of N were applied as ammonium nitrate (Nitrana), 250 kg (LN) and 500 kg N/ha per year (HN). Two-fifths of this N were applied in March and one-fifth after each of the first three cuts.

All flowers were removed daily on soya-bean plants (cv. Hampton) for 1, 2, or 3 weeks and all pods developed on the plant were removed after 1, 2 or 3 weeks of pod development, in two field trials, in order to evaluate the effects of removing flowers or pods on the growth, development and yield of the cultivar. Removal of flowers or pods led to less dry-matter accumulation, longer leaf area duration and delayed maturity of the plants and these became more pronounced with the severity of the removal.

Number of mature pods per plant, number of seeds per plant, pod yield per plant and seed yield both per plant and per hectare, were significantly reduced when flowers were removed for 1 week or pods removed after 2 or 3 weeks of development in the early season crop. Yield was reduced by 27%, 35% and 40% respectively both per plant and per hectare. In the late season crop, removing flowers for 3 weeks or removing pods after 3 weeks of development led to significant reduction in number of mature pods per plant, number of seeds per plant, number of seeds per pod, pod yield per plant and seed yield both per plant and per hectare. The magnitudes of yield reduction were 40% and 49% respectively.

The ability of the variety of soya bean used in this study to prevent significant reduction in seed yield by compensatory development, following flower or pod removal, depends on the severity of the removal vis-d-vis the stage of development of the plant and its vigour.

Two systemic fungicides, benomyl and thiabendazole, were more active than the non-systemic fungicide Drazoxolon in inhibiting fungal growth in vitro. A similar pattern was obtained in glasshouse trials with benomyl and thiabendazole giving adequate protection at low concentrations while Drazoxolon was ineffective unless applied at 50% the commercial product concentration. A field trial using thiabendazole, Drazoxolon and a mixture of benomyl and thiram confirmed the glasshouse results.

Some phytotoxicity was noticed with high concentrations of both benomyl and thiabendazole, but satisfactory disease control was achieved using fungicide concentrations which did not induce phytotoxicity.

This paper presents the results of analyses of yield variability in more than 500 trials of varieties of spring oats, spring wheat, spring barley and winter wheat. A table of critical percentage yield differences has been constructed for guidance in planning future series of trials.

The evaluation of the genetic potential of cereal varieties in variety trials will be accurate only if compensation can be made for all the variables known to influence the results, or if those variables are controlled. The influence of one such variable, seed size, on subsequent performance of crop plants, is well documented (wheat, Kittock & Law, 1968; beans, Ries, 1971; barley, McDaniel, 1969). McFadden (1963), working with barley, felt that seed size was such an important determinant of subsequent plant performance that he suggested that seed used in comparative testing systems should all be processed to the same seed range.

Previous work has shown that the technique of laparoscopy in anaesthetized ewes is a practical and reasonably accurate method for the diagnosis of pregnancy between 17 and 28 days after conception and for estimating numbers of foetuses (Phillippo et al. 1972). This method in common with other reported endoscopic techniques for sheep positions the animal on its back, necessitating the use of either general anaesthesia (Roberts, 1968; Boyd & Ducker, 1973) or tranquillization and local anaesthesia (Kelly & Allison, 1976). These methods have the disadvantages of the necessity to withhold food and water for up to 24 h prior to surgery and the risk associated with general anaesthesia and the positioning of the animal. A new procedure with the sheep standing was therefore developed from the method used in cows (Mariana, 1969; Wishart & Snowball, 1973).

Whole barley grains were soaked in dilute sodium hydroxide solutions or sprayed with concentrated solutions, then incubated in bags in the rumen of sheep. Rate of digestion was increased by the alkali, and spraying with 35 g NaOH/kg was concluded to be the optimum treatment. Whole barley treated in this way was as well consumed and digested by cattle as rolled barley, and better digested than untreated whole grain, but promoted a rumen pH one unit higher. Oats, wheat and maize were also treated successfully, as judged by digestion in bags. Urea added with NaOH remained stable; treated grain could be stored at 19% moisture without deterioration.