Effect of different levels of vitamin premix on performance, immune system status, toe bone characteristics and oxidation in thigh of broiler chickens

This experiment was conducted to evaluate the effects of different levels of vitamin premix (VP) at the last three weeks of rearing period (22 to 42 days) on performance, immune system status, toe bone characteristics and oxidation in thigh of broilers with four hundred male birds (Ross-308) in a completely randomized design with ten treatments and four replicates. The dietary treatments were: T1 without VP during 22 to 42, treatments 2, 3 and 4 with 33.33% VP, treatments 5, 6 and 7 with 66.66% VP and treatments 8, 9 and 10 with 100% VP that treatments 2, 5 and 8 only from 22 to 28, treatments 3, 6 and 9 only from 22 to 35 and treatments 4, 7 and 10 only from 22 to 42 days of age received diets containing VP. The results indicated that reduction and withdrawal vitamin premix from 22 to 42 days of age did not impair performance and toe bone characteristics. The results of thigh oxidation at three month after slaughter, did not show significant different among treatments, but after 6 month of freezing observed significant different among treatments with 66.66, 100% VP and T1 without VP (P< 0.05). The results of this study demonstrated that it is possible to reduce VP (33.33%) in the last three weeks of rearing period without any negative effects on performance, bone characteristics and meat quality.