Biannual anthelmintic treatments in village Djallonke sheep in The Gambia: effects on productivity and profitability.

An on-farm deworming trial was conducted between 1991 and 1995 on traditionally managed Djallonke sheep in The Gambia to assess the impact on productivity and profitability of prophylactic biannual anthelmintic treatments- Fifteen private flocks with an average of 25 animals per flock participated in the experiment. Half of each flock was dewormed twice a year while the other half served as the control group. The two productivity traits that were significantly improved by the treatment scheme tested were the number of lambs per lambing which increased from 1.11 +/- 0.31 (Mean +/- S.D.) to 1.19 +/- 0.39 and the number of lambings per year which improved from 1.04 +/- 0.53 to 1.22 +/- 0.47. The mortality and weight at 12 months were not significantly affected by the treatment. Monitoring of sheep sales in the flocks and on surrounding markets allowed the calculation of a rate of return to the treatment scheme tested of 246%. Despite large variations in returns. The scheme studied is recommended as over 90% of the adopting farmers would yield positive returns to their investment.