Boran cattle maintained by chemoprophylaxis under trypanosomiasis risk

Abstract

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.

Susceptibility of a Trypanosoma congolense Isolate of Water-Buffalo Origin to Diminazene Aceturate and Isometamidium Chloride

“…were used continuously to treat cattle in tsetse infested areas of East Africa for 3 years without development of drug resistance (Wiesenhutter, 1967;Wilson et al, 1975b). Indeed, recent work at Mkwaja ranch in Tanzania has demonstrated that under proper management of Samorin, cattle may be maintained for decades in tsetse-infested areas without problems of drug resistance arising (Trail et al, 1985). These data led Wilson et al (1975b) to conclude that resistance to the two drugs should not arise if used properly.…”

“…For example, production of animal protein from livestock per 1000 ha is 542 kg in Africa compared with 4113 and 38,083 kg for Latin America and Europe respectively (FAO, 1975). Trypanosomiasis transmitted by tsetse which occupy 7 of 10 M km 2 of Africa, suitable for livestock and mixed agriculture is one of the major factors thwarting livestock production (Trail et al, 1985). The increasing human population and diminishing food production has forced livestock production to be expanded into parasite and disease prevalent areas (Odhiambo, 1967;Wilson et al, 1975a, b).…”

“…The increasing human population and diminishing food production has forced livestock production to be expanded into parasite and disease prevalent areas (Odhiambo, 1967;Wilson et al, 1975a, b). Attempts to maintain livestock profitably in areas of high tsetse challenge with use of trypanocides has met with more failures than success (Trail et al, 1985). Failures have been associated with •Present Address: ILCA, P.O.…”

Trypanotolerance in cattle and prospects for the control of trypanosomiasis by selective breeding

“…Thus, some 12,000 Boran are maintained in Mkwaja Ranch in Tanzania in an area where Boran cattle rapidly succumb to trypanosomiasis if left untreated. As a result of the strategic use of isometamidium chloride (a prophylactic trypanocidal drug) in combination with diminazene aceturate (a therapeutic trypanocidal drug), the level of productivity achieved was close to that of Boran reared in tsetse-free conditions on ranches in Kenya considered among the best in the world (55). At the same time, a similar drug strategy was implemented in East African Zebu cattle (700 head) under village management in Kenya and resulted in a 20% increase in performance (32).…”

Tsetse Flies in Africa: Bane or Boon?

“…Routine veterinary care, involving carefully monitored use of curative and prophylactic drugs, will protect zebus even in tsetse areas. Under ranching systems in Tanzania there are no signs of drug resistance even after 20 years of continuous protection in high tsetse challenge areas (Trail et al 1985).…”