Evaluation of a preliminary title to protect zero-grazed dairy cattle with insecticide-treated mosquito netting in western Kenya.

The incidence of trypanosome infection was monitored in dairy cattle during a 6-month trial in Busia and Teso districts, western Kenya, to assess the efficacy of insecticide-treated netting for protection against tsetse flies. Frequently, the fragile netting did not last longer than 2 months because of destruction by strong wind or animal movements. Also, many farmers let their cattle graze freely outside the units during the day, despite technical advice, resulting in exposure of the free-ranging animals to habitats suitable for tsetse and thereby an increased risk of trypanosome infections. The trial groups thus comprised 34 animals from 11 dairy units that were continuously protected, and 153 animals from 46 dairy units that were partially protected. The control group consisted of 162 animals in 42 unprotected units. The phase-contrast buffy-coat technique was used for parasitological monitoring. The mean hazard rate for trypanosomes was significantly lower in protected cows, with a value of 0.007 as opposed to 0.02 for the control animals. Mean packed cell volumes (PCV) were significantly higher in protected cattle (29.7%) than in unprotected ones (27.6%). Farmers with protected animals also reported fewer nuisance flies and mosquitoes in their compounds.

Animal productivity in tsetse-infested area of South West Kenya

Since 1990; a baseline survey of cattle productivity has been carried out on the Olkiramatina Group Ranch; Kajiado District. The aim of this survey was to assess the impact of seasonally high tsetse challenge and the resulting trypanosome infections. Management strategies among the pastoralist farmers and the effects of traditional and introduced tsetse and trypanosomiasis control regimes were also assessed. Two traditionally managed herds (A and B) were monitored by monthly weighing and sampling for trypanosomiasis. Milk off take was recorded every two weeks and herd compositon and dynamics monitored weekly. The major constraint to productivity during the first year of the study was prolonged drought affecting traditional transhumance grazing practices. The trypanosomiasis incidence rate of a control herd was consistently higher than the trypanosomiasis prevelance rate in the survey herds. There was an increase in disease prevalence at the end of along dry season and during the short rain season. Mortality rates at this time also increased. During the period; two calving seasons were recorded; during May to June 1991 and between December 1990 and February 1991. Herd A recorded a 73.5 calving rate between November 1990 and November 1991; compared with 52 in Herd B. Differences in cattle grazing management and drug treatments between herds were recorded. Cattle performance was characterised by a large drop in the body weight of mature animals after calving; long periods of return to service and low calf growth rates. This study is on-going