ASSESSMENT OF THE EFFECT OF TSETSE CONTROL ON LIVESTOCK PRODUCTIVITY - A CASE-STUDY IN NORTHERN COTE-DIVOIRE

In order to assess the effect of tsetse control on livestock productiv ity, 21 herds of cattle of N'Dama, Baoule and zebu cross breeds in the region of Boundiali, northern Cote d'Ivoire, were monitored monthly f or trypanosome prevalence, packed red cell volume (PCV), body weight a nd reproductive performance between January 1987 and December 1989. Me an calf growth rate over the wet season of 1987, prior to tsetse contr ol, was 243 +/- 48 (standard deviation among herds) g per day; mean co w body weight in 1987 was 223 +/- 15 kg; mean cow PCV, 29.8 +/- 2.5%; mean conception rate by 6 months postcalving, 28 +/- 22%; median month ly trypanosome prevalence was 21.4% (range 3.9-32.0%) in animals under 24 months of age and 12.6% (range 0.0-44.7%) in cows. A tsetse-contro l campaign using alpha-cypermethrin-impregnated traps was introduced i n December 1987 to control trypanosomosis. Regression analyses were us ed to relate changes in mean PCV, calf growth rate, and cow body weigh t and conception rate between 1987 and 1988/1989 (the period of tsetse control) to corresponding reductions in trypanosome prevalence. An av erage 13.6 percentage unit reduction in mean trypanosome prevalence in calves between 1987 and 1988/1989 was associated with an increase of 12.2 +/- 3.6 (standard error, SE) kg in calf liveweight gain over the 7-month wet season. In cows, a corresponding 8.7 percentage unit reduc tion in trypanosome prevalence was associated with a 4.9 +/- 2.3 (SE) kg increase in body weight and a 1.3 +/- 0.3 percentage unit increase in PCV. An 18.4 +/- 8.0 (approximate SE) percentage unit increase in t he number of cows conceiving within 6 months of calving resulted from a mean decrease of 6.8 percentage units in trypanosome prevalence from 1987 to 1988. The difficulties in obtaining estimates of effects of h ealth interventions on livestock productivity that are both precise an d unconfounded with other effects over time are discussed.