Nutritional evaluation of copper-lysine and zinc-lysine complexes for chicks

Three chick experiments were conducted to evaluate two mineral-Lys complexed products, Cu-Lys and Zn-Lys. Relative bioavailability of Lys, Cu, and Zn were assessed separately using diets specifically deficient in each of these nutrients and by employing criteria that respond in a straight-line fashion to supplementation with the nutrient in question. Common-intercept multiple linear regression (slope-ratio) of weight gain, bile Cu concentration, and total tibia Zn regressed on supplemental intake of Lys, Cu, and Zn, respectively, were used to assess bioavailability values relative to the standards (i.e., L-Lys.HCl, CuSO4.5H2O, and ZnSO4.H2O). Lysine bioavailability of Cu-Lys and Zn-Lys were estimated as 89 and 109%, respectively, which were not different (P > .05) from 100%. Relative bioavailability of Cu in Cu-Lys and Zn in Zn-Lys were estimated as 120 and 106%, respectively. These values were not different (P > .05) from the standards, i.e., CuSO4.5H2O for Cu and ZnSO4.H2O for Zn.