RELATIONSHIP OF DIETARY ALUMINUM, PHOSPHORUS, AND CALCIUM TO PHOSPHORUS AND CALCIUM-METABOLISM AND GROWTH-PERFORMANCE OF BROILER CHICKS

Dietary treatments providing three levels of added Al (0, .196, or .392%) as aluminum sulfate and of available phosphorus (Pav) .45, .68, or .78%) in a factorial arrangement were administered to day-old chicks in Experiment 1. Plasma inorganic phosphorus (Pi) was significantly (P less than .05) elevated by increasing Pav and was decreased by Al. Body weight gain, feed intake, and the gain:feed ratio at Day 21 were significantly decreased by increased concentrations of Al, but were unaffected by the Pav concentrations. Decreases of 39 and 73% in weight gain and of 34 and 66% in feed intake resulted from feeding .196 and .392% Al, respectively. In Experiment 2, day-old chicks were fed diets supplemented with 0 or .392% Al in combination with .9% Ca plus .45% Pav, .9% Ca plus .78% Pav, 1.8% Ca plus .45% Pav, or 1.8% Ca plus .9% Pav. After 21 days, the supplemental Al resulted in: 1) significantly poorer growth performance; 2) decreased plasma Pi, total Ca, Zn, and Mg; and 3) decreased tibia weight and breaking strength. Elevating Pav improved growth performance, plasma Pi, and tibia weight and strength, and decreased plasma total Ca. Increasing dietary Ca significantly decreased plasma Pi and increased plasma total Ca without affecting other parameters. Increasing Pav alleviated the negative effect of Al on plasma Pi without correcting the negative effect of Al on growth performance.