Two experiments, with 288 and 192 birds, half males and half females, respectively, were carried out to determine the zinc (Zn) requirements for broilers in the growing (from 22 to 42 days) and finishing (from 43 to 54 days) phases. Two basal diets were formulated to meet the birds´ nutritional requirements, except for Zn, that was deficient at the levels of 13.0 and 12.0 ppm, respectively. In both experiments it was evaluated Zn supplementation levels, from a commercial Zn oxide, resulting in a total of 13.0, 38.0, 63.0, 88.0, 113.0 and 138.0 ppm Zn in the diet for the growing phase and 12.0, 37.0, 62.0, 87.0, 112.0 and 137.0 ppm Zn in the finishing phase. Weight gain, feed intake, feed:gain ratio and Zn concentration in the bone, liver and serum were the evaluated variables. There was no significant effect of the Zn levels on the performance traits. There was effect of the Zn levels on the Zn concentration in the serum and in the bone in the growth phase. Sex effect and interaction between sex and levels of Zn in the diet were observed on Zn concentration in the bone. In the finishing phase, there was effect of the Zn levels in the diet on the Zn concentration in the liver and there was sex effect with males presented greater Zn deposition in the bone and in the liver. The Zn requirements for broilers in the growth phase, considering the variable Zn in the bone, is 82.20 ppm for the males and 85.70 ppm for the females. In the finishing phase, levels from 25 to 30 ppm, considered normal for corn and soybean meal diets, were sufficient for adequate bird performance.
bone; liver; mineral; requirement; serum
