Studies on duck nutrition. II. Calcium and phosphorus requirements of mule ducklings

Experiments were conducted to determine calcium and phosphorus requirements of mule ducklings. Two-day-old, straight-run mule ducklings were fed diets containing graded levels of calcium or phosphorus for three weeks. Weight gain, feed consumption, tibia ash content, and levels of serum calcium and phosphorus were used as criteria for the determination of the optimum dietary calcium and phosphorus levels required by the ducklings. The minimum calcium requirements were .48% and .58%, respectively, for maximum growth and optimum tibia ash content as determined by regression analysis of body weight gain and tibia ash content against calcium level in the diet. The minimum available phosphorus requirements were .26% and .34%, respectively, for maximum body weight gain and optimum tibia ash content as determined by the same method.