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

Abstract

Ten farm flocks in north-west Syria were monitored over four years to determine the effect of gastro-intestinal and lungworm nematode infections on Awassi 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 later 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 no beneficial effect on ewe fertility, mortality and survival. But in spring treated ewes were heavier and generally had better body condition than untreated ewes, and this was associated with heavier lambs at birth and at weaning. Stepwise regression analysis suggested that better management, such are more rigorous culling, resulted in higher ewe fertility and survival. The overall effect of treatment on annual ewe productivity was small, equivalent to 0.5–1.0 kg additional lamb weaned per ewe exposed to rams. This covered the cost of the treatment. The trial demonstrated that useful studies on nematode parasites can be conducted in farm flocks and this gives the results added value for predicting the impact of treatment on other flocks in north-west Syria.