The effect of the substitution of an antibiotic by different levels of spent mushroom substrate (SMS) of Agaricus blazei on the performance of broiler chicks from 1 to 42 days old was evaluated. Seven diets were evaluated, six with SMS addiction (0.0, 0.2, 0.4, 0.6, 0.8, and 1.0%) and one with antibiotic (avilamycin 10 ppm). A total of 588 one day old chicks was allotted to a complete randomized design, with six replications per diet (three per sex) and 14 birds per experimental unit. The birds fed diet with any additive showed the worst performance results. Levels of SMS above 0.4% caused gradual reduction in the performance. The level of 0.2% of SMS provided the highest value of weight gain and of 0.21% promoted the best feed conversion and the highest value of feed intake. With exception of chest and abdominal fat yield, no additive effect on carcass and cuts yield was observed. The spent mushroom substrate of Agaricus blazei can be used as additive alternative to the antibiotic at the level of 0.2% of the diet; therefore it did not harm the productive performance and carcass yields of the birds.
addictives; antibiotics; broilers; medicinal fungi; nutrition; performance
