The effect of citric acid on the calcium and phosphorus requirements of chicks fed corn-soybean meal diets

Data previously reported from our laboratory indicated that supplementation of a corn-soybean meal diet with citric acid improves P utilization in chi cks. The four experiments reported herein were conducted to further evaluat e the effects of citric acid on Ca and P utilization for chicks fed a corn- soybean meal diet. Diets in all experiments were fed to chicks from 8 to 21 or 22 d of age. The first experiment evaluated the effect of 6% citric aci d on the Ca requirement of chicks. A Ca-deficient basal diet [23% CP, 0.54% Ca, 0.45% available P (AP)] containing 0 to 0.7% supplemental Ca in 0.1% i ncrements was fed with or without 6% citric acid. The results indicated tha t citric acid did not significantly affect the Ca requirement. A second exp eriment evaluated different levels of citric acid (0, 2, 4, or 6%) on P uti lization, and results indicated that 4 and 6% citric acid produced the larg est responses in growth and tibia ash. Experiments 3 and 4 were then conduc ted to determine whether 4 or 6% citric acid would reduce the level of supp lemental P required. Dietary treatments were a P-deficient basal diet (23% CP, 1.0 or 1.3% Ca, 0.20% AP) supplemented with 0 to 0.25% inorganic P with or without 4 or 6% citric acid. When diets contained citric acid, weight g ain and tibia ash were maximized at lower AP levels than when diets contain ed no citric acid. The results of this study indicate that citric acid incr eases P utilization in corn-soybean meal diets and reduces the AP requireme nt by approximately 0.10% of the diet.