The dietary effects of digestible lysine and chelate zinc for male broiler chickens from 22 to 42 days of age were evaluated in two experimental assays. A complete randomized block experimental design in a 5 × 2 factorial, with five lysine levels (0.841, 0.876, 0.997, 1.022 and 1.030%) and two levels of zinc (43 and 243 ppm) was used. In the first assay, it was used 900 birds with initial average weight 957.4 g distributed in experimental units with 30 birds and three replications and in the second assay, 180 broilers with initial average weight 866.22g split in plots with 3 birds and six replications were used. The characteristics evaluated were performance, cut yield and body composition (1st assay), nitrogen balance and apparent digestibility of diets (2nd assay). There was an interaction among levels of lysine and zinc for weight gain, feed conversion, ingested dry matter and energy balance. Yields of breast, thigh and drumstick had linear increases in response to increments in the level of digestible lysine in the diet. The best performance was obtained for level 0.997% of digestive lysine (or 1.134% total lysine) and level of 43 ppm zinc. For higher cut yields, the recommended level of digestible lysine has to be at least 1.002% (or 1.139% total lysine), regardless to the levels of chelate zinc. Greater inclusion of zinc in diets for broiler from 22 to 42 days of age does not improve the utilization of dietary lysine and increases body fat deposition.
lipid deposition; performance; protein deposition; retained nitrogen
