Citric acid does not improve phosphorus utilization in laying hens fed a corn-soybean meal diet

Data previously obtained from our laboratory have indicated that citric acid was very effective at improving phytate-P utilization in chicks fed a P-deficient corn-soybean meal (SBM) diet. The objective of the current study was to determine if citric acid would have similar effects in a commercial strain of Single Comb White Leghorn laying hens (n = 432) fed a corn-SBM diet containing 0.10% available P (AP). Dietary treatments were a corn-SBM basal diet (0.10% AP, 3.8% Ca, and 17% CP) supplemented with 0, 1, 2, 3, or 4% citric acid and a positive control diet containing 0.45% AP. Each of the six dietary treatments were fed to six replicate groups of 12 hens from 22 to 40 wk of age. No significant differences in performance were observed among treatments during the first 4 wk of the experiment. Hen-day egg production, feed consumption, feed efficiency, and egg yield were subsequently depressed in hens fed 0, 1, 2, 3, or 4% citric acid compared with hens fed 0.45% AP. The results of this study-indicate that citric acid does not improve the utilization of dietary P in laying hens fed a corn-SBM diet containing 3.8% Ca.