The physiological effects of feeding warfarin poultry

A 20 week study using layer and broiler strain chicks of both sexes was undertaken to determine whether poultry were susceptible to warfarin-induced granulomatous endocardial lesions. Birds were fed a corn-soybean meal basal diet with no added vitamin K, supplemented with either 0, 25, 50, or 100 ppm of warfarin or vitamin K at .6 mg/kg of diet. Broiler chicks showed a higher incidence of hemorrhages, more mortality, and longer prothrombin times than did the layer strain fed the same diets. Regardless of the breed, female chicks fed the highest warfarin level had significantly longer prothrombin times than the male chicks. However, there were no sex differences associated with mortality or incidence of hemorrhages among birds fed the experimental diets. Growth was most significantly reduced for chicks fed the highest warfarin level and to a lesser degree for birds fed 50 ppm of warfarin. In contrast to the first 10 weeks of the study, there was a sharp decline in mortality, incidence of hemorrhages, and prothrombin times during the last 10 weeks of the study. Layer and broiler strains of chickens fed warfarin for 20 weeks showed no evidence of granulomatous endocardial lesions as was reported for swine (Oshiro and Brooks, 1975).