EFFECTS OF 3 NEMATODE ANTHELMINTIC TREATMENT REGIMES ON FLOCK PERFORMANCE OF SHEEP AND GOATS UNDER EXTENSIVE MANAGEMENT IN SEMIARID KENYA

A study was undertaken in a semi-arid area of Kenya between August 199 1 and June 1993 to evaluate the effects of anthelmintic treatment usin g ivermectin before or during the rains, on performance of mixed sheep and goat flocks, in comparison with an untreated flock. Performance p arameters measured included age and weight of dams at first parturitio n, parturition intervals, body weights of dams and offspring, and birt h weights, growth rates, and mortality rates of offspring. Among these parameters, birth weights and growth rates of offspring were found to be significantly improved by the treatment administered before the ra ins compared with the other two treatments. Mortality was lower in lam bs and kids with high birth weights. Treatment, either before or durin g the rains, significantly reduced the faecal egg output and improved body weight, packed cell volume and flock fertility. Liveweight was co nfirmed to be a better measure of sexual maturity than age. It was fur ther shown that lambs and kids, born of darns at their first lambing o r kidding, experienced higher mortality rates than lambs and kids born of dams in their second and subsequent parturitions. Overall, treatme nt with ivermectin before the onset of rains was equal to or better, i n terms of the performance parameters measured, than treatment during the rains, whilst treatment compared with no treatment increased perfo rmance in almost all of the parameters measured.