THE EFFECT OF DIETARY SUPPLEMENTATION WITH COPPER-SULFATE OR TRIBASICCOPPER CHLORIDE ON BROILER PERFORMANCE, RELATIVE COPPER BIOAVAILABILITY, AND DIETARY PROOXIDANT ACTIVITY

Three experiments were conducted to study Cu sulfate and tribasic Cu c hloride (TBCC) as sources of supplemental Cu for poultry. In Experimen t 1, 252 chicks were fed the basal corn-soybean meal diet (26 ppm Cu) supplemented with either 0, 150, 300, or 450 ppm Cu from Cu sulfate or TBCC for 21 d. Chicks fed 450 ppm Cu from sulfate had lower (P < 0.05 ) feed intake than those consuming other diets. Feeding Cu increased ( P < 0.0001) liver Cu linearly with increasing dietary Cu regardless of Cu source. The slopes of regression of log(10) Liver Cu on dietary Cu intake did not differ between sources (P > 0.10). Linear regression o ver nonzero dietary levels of log(10) transformed liver Cu concentrati on (parts per million of DM) on analyzed total Cu intake (micrograms) resulted in a slope ratio estimate of 106 +/- 19 for bioavailability o f Cu from TBCC compared to 100 for that in Cu sulfate. In Experiment 2 , a 42-6 floor pen study was conducted with 1,260 broiler chicks given the basal corn-soybean meal diet supplemented with 0, 200, 400, or 60 0 ppm Cu from either feed-grade Cu sulfate or TBCC. Body weight and fe ed conversion did not differ in birds fed up to 400 ppm Cu from either source. Birds given 600 ppm Cu from either source had lower feed inta ke, poorer growth, and feed conversion (P < 0.0001). Liver Cu increase d (P < 0.0001) linearly with increasing dietary Cu. Based on log(10) l iver Cu concentration, Cu in TBCC was 112% available compared to 100% for the standard Cu sulfate. In Experiment 3, Cu sources were added to broiler starter diets at concentrations of 25, 100, and 300 ppm Cu an d diets were stored at an elevated temperature to examine the effect o f particle size on oxidation. Diets were stored at 37 C for up to 20 d and samples were removed at 4-d intervals. At 300 ppm added Cu, oxida tion in TBCC diets was lower (P < 0.0001) than oxidation in diets fort ified with coarse Cu sulfate, even though TBCC modal diameter for part icle size was almost seven times smaller. Oxidation promotion by Cu su lfate was much greater with fine than in coarse sized particles for al l three fortification levels.