Prophylactic Efficacy of Nifursol Against Different Levels of Exposure to Histomoniasis in Turkeys 4 to 9 Weeks of Age ,

Abstract

Three experiments were conducted with B. B. Bronze and B. B. White turkeys, four to nine weeks of age. Poults were fed 12.5, 25, 37.5, 50 or 75 p.p.m. (or 0.00125, 0.0025, 0.00375, 0.0050, and 0.0075%) of nifursol and given graded levels of exposure to histomoniasis. The exposure levels consisted of graded doses of infective material (embryonated Heterakis gallinae ova) administered orally. Histomoniasis mortality was recorded during post-exposure periods of 27–35 days; dead birds were examined for hepatic and cecal lesions typical for histomoniasis. Birds which survived the post-exposure period were sacrificed and examined for hepatic and cecal lesions.Graded doses of infective material caused graded levels of mortality and morbidity only in poults fed the unmedicated diet in two experiments. Dietary levels of 37.5, 50, 75 and 100 p.p.m. of nifursol were equally effective in preventing histomoniasis mortality and morbidity. In one experiment, both 12.5 and 25 p.p.m. of nifursol completely prevented mortality and morbidity among poults given graded doses of infective material. However, 20.8 percent mortality and 27.1 percent morbidity occurred among poults fed 12.5 p.p.m. of nifursol in another experiment. The minimum effective level of nifursol in feed for prevention of histomoniasis mortality and morbidity was between 25 and 50 p.p.m. Level of exposure or dose of infective material given poults had very little influence on the efficacy of nifursol treatments.