The aim of this work was to evaluate the effect of broiler breeders’ age and yeast wall (YW) levels on broilers’
performance and macrophage activitys. The experiment consisted in a completely randomized design and a 2 X 5
factorial arrangement and two controls of two broiler breeders age (34 and 57 weeks of age) and five YW levels
(zero, one, two, three or four kg of YW/ton of diet). They received sorghum diet compared to a control corn/soybean
meal diet. The age of the broiler breeders influenced the performance, but did not affect macrophage activity. At 34
weeks age broiler breeders’ progeny, all diets were similar considering the average weight. For 57 weeks age
broiler breeders’ progeny, at 21 days, only average weight of sorghum diet supplemented with 4 kg/ton was similar
to corn diet results. The optimum level of YW for maximal macrophage activity was 2.06 kg/ton of meal.
