Demonstrated effects of S 6 -

s of papers 35 142 Citric acid improves phytate phosphorus utilization in two breeds of chicks fed a corn-soybean meal diet. K. A. Rafacz*, C. Martinez, J. L. Snow, D. H. Baker, and C. M. Parsons, University of Illinois. Previous research in our laboratory has shown that citric acid improves phytate phosphorus utilization in crossbred chicks (New Hampshire x Columbian) fed a P-deficient corn-soybean meal diet. The current study was conducted to determine if citric acid is also effective in commercial broiler chicks (Ross x Ross). In two experiments, four replicate groups of five male crossbred chicks and male commercial chicks were fed cornsoybean meal diets varying in citric acid (CA) and nonphytate phosphorus (NPP) from 8-21 days of age. In Experiment 1, a 2x2x2 factorial design was utilized to evaluate the effect of two levels of CA (0 and 3%) and NPP (0.13 and 0.28%) in crossbred chicks and commercial chicks. The commercial chicks, but not the crossbred chicks, fed the 0.13% NPP diet were removed from the experiment after 3 to 5 days due to very poor growth and severe leg problems. Chick weight gain and tibia ash were significantly increased (P<0.05) by CA in crossbred chicks fed 0.13% or 0.28% NPP and in commercial chicks fed 0.28% NPP. In Experiment 2, the same 2x2x2 factorial design was again used except that the NPP levels were increased to 0.18% and 0.33%. Once again, tibia ash was increased significantly (P<0.05) with the addition of CA in both breeds of chicks, and the response was greater at 0.18% NPP than at 0.33% NPP. These results indicate that CA improves phytate phosphorous utilization in both crossbred (New Hampshire x Columbian) and commercial broiler chicks (Ross x Ross).