ABSTRACT
Screening of 600 sheep for gastro-intestinal helminths revealed that 395 were harbouring nematodes eggs with an overall incidence of 65.83 percent. Lambs aged 3-12 month were more susceptible for parasitic infestation [71.74%] followed by animals over 2 years old [63.15%]. The highest rate of infection was noticed during autumn and winter while moderate drop was observed during spring and summer seasons. Haemonchus contortus, Tri-chostronylus spp., Ostertagia spp, Bunstomum spp., Chabertia ovina, Stronyloides papillosus, Nematodirus spp. Oesophogostomum spp. and Trichuris ovis were identified through faecal culture. The antihelmintic efficacies of ivermectin, fenbendazole, oxfendazole and thiabendazole were tried. All durgs were being effective as reducing the faecal egg counts of trichostro-ngylus spp. from nil to 7 days after medication. Thiabendazole failed to remove Trichuris ovis burdens while a cure rate of 100 percent was obtained by ivermectin injection. Strongyloides papillosus infection was reduced by 100% and 90.63% with ivermectin and fenbendazole respectively. Significant decrease [P < 0.05] of erythrocytic count, haemoglobin content, packed cell volume percent, serum total proteins and serum albumin and significant increase [P < 0.05] of total leucocytes, eosinophils, neutrophils, immature neutrophils, monocytes and serum globulins were the noticeable changes in sheep naturally infected with gastrointestinal nematodes. These changes were more or less normalized after the end of treatment depending upon the type and severity of infection and the efficacy of antihelminthic used. Significant decrease of RBCs, Hb content, serum total proteins, serum albumin as well as leucocytosis were the noticeable changes in sheep naturally infected with gastro intestinal nematodes