Increasing Dietary Phosphorus Retention and Decreasing Fecal Phosphate Excretion in Modern Commercial Broilers

[摘要] Phosphorus is a potential environmental pollutant.The objectives were to minimize fecal phosphorus (P) by optimizing the efficiency of utilization of dietary available phosphorus (aP) for carcass and skeletal growth.In two experiments, Arbor Acres X Arbor Acres male broiler chicks were fed from 0-3 weeks of age a diet adequate in vitamin D, calcium (Ca) and P (National Research Council (NRC) 1994).Experiment 1A assessed body weight gain and whole dry skeletal weight at 2,4,6,and 8 wks of age. Experiment 1B used a central composite, rotatable experimental design with dietary Ca from 0.55% to 0.85% and aP from 0.15% to 0.45% from 4 to 7 wks of age.Decreasing the dietary Ca:aP produced a statistically significant (P<.05) increase in %P retention and a decrease in % fecal total P.Experiment 2 used a dietary Ca:aP = 2.0.In 2A, aP varied from 0.25% to 0.4% for age 3-6 wks and 0.25% to 0.35% for age 6-7 wks.There were no effects on body weight or bone ash. Experiment 2B was a P retention, depletion/repletion study from 28 to 45days (d) of age.The 7 treatments varied in dietary aP from 0.25% to 0.40% for age 28-40 d and from 0.30 to 0.45% for age 40-45 d. Measurements were taken from 41 to 45 d of age.Retention of total P and phytate P were significantly increased and total fecal P and fecal phytate P were significantly reduced compared to the NRC-based control treatments when the broilers were fed a P-adequate diet from 40-45 d of age after having been fed a low P diet from 28-40 d of age.Body weight and bone ash were not affected.In conclusion, subsequent experimental designs should evaluate treatments in which dietary Ca and aP would bracket the following values: (1) dietary Ca:aP =2.22, aP=.45% for 1-20 d of age; Ca:aP=2.0, aP=.35% for 20-30 d of age; Ca:aP=1.7, aP=.35% for 30-40 d of age.Repletion would utilize Ca:aP=2.0, aP=.35 until market age.

[发布机构] University:North Carolina State University

[效力级别] Phosphorus

[关键词] Retention;Phosphorus;Phosphate;Excretion;Broilers