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The effects of implementing a restricted suckling regime with crossbred dairy cows have been examined in the Ethiopian highlands. Calves were allowed to suckle their dams for two minutes before each milking until weaning and this system was compared with the common practice of rearing by bucket feeding. Restricted suckling significantly increased calf growth rate to weaning, from 0.31 to 0.53 kg/d (P less than 0.01). No differences in calf growth post-weaning occurred, so that the 20 kg difference in liveweight that had been achieved by the restricted suckled calves by the time of weaning persisted until the calves were nine months old, when observations ceased. Total milk offtake was not significantly affected by treatment, although that obtained from the partially-suckled animals over their whole lactation exceeded that from the other treatment by 15%. Partial suckling delayed return to oestrus post partum but this was offset to some degree by fewer services per conception, hence calving interval was not significantly increased. Voluntary feed consumption was similarly unaffected and it is concluded that restricted suckling offers tangible advantages for adoption by smallholders using crossbred cows in dairy production systems.

Reproductive performance, mortality, growth, and culling and replacement rates based on 20000 calving records were evaluated for grade Boran beef cattle maintained with trypanocidal drugs in an area of high trypanosomiasis risk in Tanzania. Under ranching conditions, over a 10-year period in this area of high Olossina morsitans morsitans, O. pallidipes and O. brevipalpis challenge, a calving interval of 15-9 months, pre-weaning mortality of 8%, annual cow mortality of 5-8% and 8-month weaning weight of 133-5 kg resulted in a herd productivity of 96 kg of weaner calf per cow per year. The proportion of heifers required as replacements (45%) and the generation interval (6-9 years) indicated scope for implementation of selection programmes on growth traits. The level of productivity achieved compared favourably with major data sets recently analysed from pure Boran cattle under trypanosomiasis-free ranching conditions in Kenya, and from trypanotolerant N'Dama cattle in West Africa. These results indicate the possibility of improving livestock production in tsetse-infested areas by the rational use of chemoprophylaxis as an integral part of management.Year, season, cow age, calf sex and location on ranch had significant effects on practically all the traits of calving interval, pre-weaning mortality and growth, and cow productivity. Superior performance where bush clearance and tsetse fly control had taken place suggests that economic evaluation of these interventions should be attempted. The season of calving had a major effect on productivity. Cows of 5-8 years of age were the most productive, as were animals producing male calves, features well recognized in beef cattle production.An average of 4-4 treatments with Samorin, a prophylactic, and 0-6 treatments with Berenil, a therapeutic, were required per year. The number of treatments varied from year to year and by area, being greater in the south of the ranch where the tsetse challenge was considered higher. However, the age and season of calving had little effect on the number of treatments required. Despite such extensive use of trypanocidal drugs, there was no indication that drug resistance had developed or evidence that repeated inoculation of Samorin had affected productivity.Grading-up of small East African Zebu cattle to Boran over an 8-year period allowed annual comparison of birth weights, pre-weaning growth and weaning weights of two groups of calves, one having a higher level of Boran genes (varying from 12 to 6% higher annually) than the other. Those with the higher level of Boran genes performed better by 3-3% for all attributes studied, but as the percentage difference in Boran genes decreased, so did this difference. In an environment improved through bush clearance and tsetse fly control, the calves with higher levels of Boran genes were superior, but this superiority was not expressed in the unimproved environment.

Data were obtained on 178 clutches of African Barn Owls in central Mali from four breeding seasons during 1979–1983. Significantly more clutches were laid in 1979–1980 and significantly fewer in 1980– 1981 than the average for the 4 years and there were significantly more clutches laid in the middle period of the annual breeding season. The egg volume was significantly smaller at the beginning of the breeding season and significantly larger in the middle than the overall mean with eggs of second clutches being larger than those of first clutches. The clutch size was 605 eggs of which 479 hatched. The number of young fledged per successful nest was 319 and was 1 83 for all nesting attempts. The month was the only variable shown to affect significantly the clutch size, eggs hatched and fledging rate, the highest success rates being associated with the middle of the breeding period. The average interval between the hatching of eggs was 2–31 days. Survival rates (47'1%) to fledging were significantly affected by year (1981–1982 being the least) and month (mid‐season birds the best). The order of hatching significantly affected age at death or disappearance, the first‐hatched birds surviving the longest. The year significantly affected age at fledging, the young from the year in which most clutches were laid leaving the nest at the youngest age and those associated with the year having the least number of clutches remaining in the nest the longest. The month of hatching also affected fledging age, birds at the extremes of the breeding season fledging at older ages. The discussion compares these data with those from elsewhere.