Effects of Azadirachta indica on Sheep Infected Naturally with Helminthes

The objective of this study was to evaluate the effects of neem (Azadirachta indica) on natural helminthes infection in lambs. Forty, four-month-old entire Santa Ines lambs were grazed on pasture, over a 20 week period. They were divided into 4 treatments: Without drenching (ND), 3 g A. indica/animal (A₃), 6 g A. indica/animal (A₆) and 9 g A. indica/animal (A₉) over 5 consecutive days, with an interval of 25 days between drenchings. Faeces were collected weekly and lamb weight and blood collection were carried out fortnightly. Four weeks after the last drenching all lambs were slaughtered, and worm burdens calculated. No significant differences were observed for lamb performance between treatments. Blood parameters highlighted the progress of the worm infections, with sheep on treatments A₆ and A₉ ending the experiment showing anemia. There was an increase in the total number of worms associated with increasing levels of neem, especially due to the increase in number of H. contortus in detriment to the number of T. colubriformis for highest levels of neem (A₆ and A₉). The increasing doses of neem did not improve the control of endoparasites in sheep naturally infected.