Quasi-absence of trichostrongylid reinfection in Gambian livestock during the dry season

Abstract

Five Ndama bulls aged between 1.5 and 2 years and 20 Djallonke rams aged between 6 to 18 months were dewormed as follows: the bulls were dewormed in November (beginning of the dry season), the sheep were divided into four groups dewormed in November, January, March and May respectively. The animals were kept on naturally infected pastures prior to and throughout the experiment. Gastro- intestinal nematode egg excretion was measured weekly after starting the treatment. Egg excretion stayed practically nil for all animals except for the series of sheep treated in May which started excreting eggs on month after the first rain. The bulls were slaughtered in June and the sheep were slaughtered nine weeks after they had been initially dewormed. A complete parasitological post mortem examination confirmed the absence of any pathologically consequent reinfection by gastro-intestinal nematodes of Gambian cattle during the dry season. This confirms the strategic importance of the application of a dewormer also efficient against immature trichostrongylids at the beginning of the dry season and renders complementary deworming between November and May superfluous.