Abstract
The effects of supplementation with chelating agents on the growth performance of chickens fed high calcium diets were investigated in 2 experiments.
In experiment 1, increasing dietary calcium to 25.2 g/kg significantly reduced body weight gain and feed efficiency. The addition of phytic acid (10 g/kg) tended to improve body weight gain of chickens fed high calcium diets; however, the gain was not significantly different from that of birds fed the high calcium diet. The addition of either Na2EDTA (1 g/kg) or proline (10 g/kg) to a high calcium diet did not affect body weight gain or feed efficiency of chickens.
In experiment 2, increasing dietary calcium to 26 g/kg significantly reduced body weight gain and feed efficiency and increased plasma total calcium concentration. The addition of cellulose significantly (P < 0.01) reduced plasma calcium and tibia calcium concentrations; however, the performance of chickens fed high calcium diets was not affected by the addition of cellulose.
It was concluded that chelating agents differ in their ability to eliminate the toxic effects of high calcium diets, and that the addition of phytic acid at 1% was most successful in eliminating the growth depressing effect of high dietary calcium.