A study was made of reproductive performance in 183 maiden and 218 mature ewes from a single Merino flock either with or without lupin grain supplement (Lupinus angustifolius cv. Uniwhite) at 500 g/head/day from 14 days prior to the introduction of the rams until 12 days post coitus. The ewes were grazed either on irrigated perennial pasture or hay fed on a fallow area. Ovulation rates increased (P < 0·01) in ewes which received the supplement. Insemination rates were not affected by the supplement, although embryo survival was reduced (P < 0·05). Feeding the lupin grain supplement did not increase the number of embryos present at days 28·31 post coitus. Ovulation rate and embryo survival were not influenced by diets of irrigated pasture or hay, although insemination rates of ewes tended to be lower when ewes grazed the irrigated pasture rather than hay.

The term game is applied to those wild animals which are pursued in the chase or kept for pleasure. When an animal has been domesticated it belongs to the family, lives in or near the habitations of man and is tame, not wild.

Wild African buffalo, eland, oryx and gazelle were caught by either dart-immobilization, chasing and roping, or driving into a corral. Weaned, sub-adult animals were preferred. The taming procedures started in small, dark, padded cells and progressed through a series of larger enclosures until the animals were grazing in a 40 ha paddock 7 weeks after capture. Gazelle was the only species which was not established as a domestic herd by this method, because of its liability to self-inflicted injuries.

The domestic game animals were grazed over thousands of hectares without fencing, but under supervision of herdsmen. They were subjected to standard domestic animal husbandry procedures including eartagging, dehorning and castration.

The conclusion is that some African game animals are easy to domesticate as has also been demonstrated in the prehistoric and recent past. The reason they have not displaced conventional livestock can be found in the history of domestication. The condition originated in the Middle East and spread mainly by the introduction of an alien culture and livestock to Africa. The time when sub-Saharan Africans had established a suitable way of life for domestication coincided with the arrival of cattle, sheep and goats forced south by the desiccating environment.

The potential of African game animals to domestic animal production will be evaluated in subsequent papers.

Grain yield and incidence of take-all were measured in barley grown continuously and in successive barleys after two crops (oats, beans) not susceptible to the take-all fungus. Without fertilizer N, first barley crops after beans yielded about 1 t/ha more than second barleys and 2 t/ha more than third; growing more barleys did not further lessen yield. With increasing amounts of fertilizer N yields of barleys after barley nearly equalled yields of barley after beans. Take-all increased to a maximum in third barleys and was decreased by N, but it was not possible to separate the effects of take-all andsoil and fertilizer N on yield.

Rumen fermentation, duodenal digesta flow and N balance were studied in three sheep fed diets which contained urea or fishmeal as nitrogen supplement and either barley straw, barley + corn starch or molassed wheat straw (60% molasses) as carbo-hydrate source.

The molar composition of rumen volatile fatty acids (VFA) with straw diets was high in acetate (64–68%), with barley diets high in propionate (32–36%) and with molasses diets high in butyrate (28–34%). Rumen ammonia concentrations (RAC) were low and constant with fishmeal diets (< 10 mM) but varied with carbohydrate source with urea diets. RAC was very high (24 mM) after feeding molasses + urea.

With barley and molasses diets 73–75% of digestible dry matter (DDM) was digested in the stomach, but only 54–59% with ground and pelleted straw diets. For all diets less N passed the duodenum than was eaten. The lowest daily duodenal N passage was with molasses + urea. Daily urinary N output was highest (P < 0·01) for this diet and nitrogen balance lowest.

Daily intakes of amino acids differed widely between diets but differences in duodenal passage were not so great. Molasses + urea provided the lowest values for daily duodenal amino acid flow. The amino acid content of duodenal N (mM amino acid/16 g N) was relatively constant despite broad variation between diets. Digesta alanine and valine (mM/16 g N) were higher for barley than for straw diets (P < 0·05). Digesta methionine (mM/16 g N) was lower for fishmeal than for urea diets (P < 0·01).

Very little sucrose reached the duodenum with any diet.

It was concluded that the form of energy-yielding nutrient inuflenced duodenal N flow by affecting ammonia-N capture in the rumen, but that the amino acid content of duodenal N was little affected. The interaction between molasses and urea was not beneficial to efficient use of urea-N in this work when molasses was the major carbohydrate component of the diet.

Sugar yield increases from irrigation in 19 experiments on a sandy-loam soil at Broom's Barn over an 11-year period were examined in relation to rainfall and to both potential and measured soil moisture deficit. Irrigation increased average yield from 7·6 to 8·3 t sugar/ha and in six of the years significantly increased yield by more than 1 t sugar/ha (15%). The experiments also tested plant density, nitrogen, harvest date and time and amount of irrigation. Without irrigation, maximum sugar yield was from a density of 74000 plants/ha but larger densities gave slightly more yield when irrigated. Irrigation affected the magnitude of response to nitrogen but 100 kg N/ha gave the most profitable yield increase, both with and without irrigation. Yield increases of about 1 t sugar/ha (15%) between early and late harvesting were also independent of irrigation. Early irrigation of 25 mm and 50 mm in June and July respectively increased yield in 4 of the 5 years but in all years applications in late summer did not increase sugar yield. The main factors controlling the yield response to irrigation were period and size of deficit. The soil type and summer rainfall at Broom's Barn were compared with those in 36 other experiments at five localities between 1947 and 1973; yield increases at Broom's Barn were smaller, probably because the others were on lighter soils.

A model which takes account of heterosis for total seed yield and autofertility was used to trace the evolution of the expected average inbreeding coefficient (F) of a synthetic variety of field beans under multiplication. In every case, the value of F rapidly approached an equilibrium value which depended largely on the amount of cross-fertilization and very little on the higher seed total set or amount of selfing on less inbred plants. There was no indication of any fluctuation in F from generation to generation when the proportion of cross-fertilization was constant. The possibility of reducing the coefficients of inbreeding of generations likely to be used on the farm (syn-4 and later) by hand pollination instead of open pollination of the parents and by promoting cross-pollination by artificial increases in numbers of bees or adjustment of environmental factors during multiplication were examined. Although the method of parental pollination had little effect, induced increases in bee activity led to significant reductions in F when the ambient frequency of bee pollinations was low. The generation at which this procedure gave the maximum effect was the final generation of seed increase (syn-3), but an alternative would be for farmers to use bees on the first commercial crop. In any case, only seed from crops with adequate bee pollination should be used to sow commercial crops.

As the breeding system was shown to be effectively very similar to one in which all plants are equally self-fertile, it should be possible to take account of the number (n) and coefficients of inbreeding (F0) and interrelationship (r0) of the parents, and to predict the yield of advanced generations using formulae given by Busbice (1969, 1970).

The effects of osmotic pretreatments were tested on the germination responses of oat and wheat grains. Temperature and duration of the pretreatment with polyethylene glycol (PEG) at two osmotic potentials (OP) were the experimental variables. The rate and synchronization of germination at 5–25 °C were significantly improved in both species by osmotic pretreatments compared with untreated controls. Maximum promotive effects were obtained after pretreatment periods of 6 and 4 days at – 10 bars at 5 and 10 °C respectively, and after 3 days at – 20 bars at 25 °C. Rapid and synchronized germination of seeds may be of advantage by minimizing their exposure to environmental hazards at early stages following imbibition and by allowing more favorable competition with other fast-germinating and growing species.

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).

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.