Effects of gastro-intestinal and lungworm nematode infections on ewe productivity in farm flocks under variable rainfall conditions in Syria

Ten farm flocks in north-west Syria were monitored over four years to deter mine the effect of gastro-intestinal and lungworm nematode infections on Aw assi ewe productivity. A group of ewes in each flock served as the control, while the other was treated with fenbendazole in the autumn and in spring. The flocks were visited each month to start with and every three months la ter in the trial to collect faecal samples, and recordings were made of ewe and lamb live weight, ewe body condition score, changes in flock inventory and supplementary feeding practices. Treatment with the anthelmintic had n o beneficial effect on ewe fertility, mortality and survival. But in spring treated ewes were heavier and generally had better body condition than unt reated ewes, and this was associated with heavier lambs at birth and at wea ning. Stepwise regression analysis suggested that better management, such a re more rigorous culling, resulted in higher ewe fertility and survival. Th e overall effect of treatment on annual ewe productivity was small, equival ent to 0.5-1.0 kg additional lamb weaned per ewe exposed to rams. This cove red the cost of the treatment. The trial demonstrated that useful studies o n nematode parasites can be conducted in farm flocks and this gives the res ults added Value for predicting the impact of treatment on other flocks in north-west Syria. (C) 2000 Elsevier Science B.V. All rights reserved.