Effect of microbial phytase on nitrogen and amino acid digestibility and nitrogen retention of turkey poults fed corn-soybean meal diets.
The effect of microbial phytase on N and amino acid (AA) digestibility and N retention was investigated in a 29-d trial using 480 Nicholas Large White Turkey female poults fed corn-soybean meal diets. A 2 x 2 x 2 factorial arrangement of treatments was used with 0.45 and 0.60% nonphytate P (nP), 22.5 and 28.0% CP, and 0 and 750 U of microbial phytase/kg of diet. At 0.45% nP, adding phytase to either 22.5 or 28.0% CP diets increased BW gain (P < 0.01), and percentage (P < 0.01) and weight (P < 0.10) of toe ash; at 0.60% nP, the magnitude of the effect of phytase was less (P > 0.10) than observed for 0.45% nP and inconsistent. Apparent and true ileal digestibility of N and AA was estimated by using chromic oxide as an indicator at Day 24. At 0.45% nP, adding phytase to 22.5% CP diets tended to improve the apparent and true ileal digestibility of N and AA, except cysteine or methionine; adding phytase to 28.0% CP diets increased the digestibility of N and most of the AA (P < 0.001 to 0.10). At 0.60% nP, adding phytase to 22.5% CP diets increased the apparent and true ileal digestibility of N and all the AA (P < 0.001 to 0.10), but did not change digestibilities at 28.0% CP diets. Adding phytase also increased (P < 0.001 to 0.10) apparent ileal digestibility of DM and P at 0.45% nP for both CP diets, but only for 22.5% CP diets at 0.60% nP. The total excreta were collected at Day 27 to 29. Adding phytase to 0.45% nP diets increased apparent utilization of DM (P < 0.01 to 0.10) and retention of N (P < 0.05 to 0.10) at both CP levels; retention of P was only increased (P < 0.10) at 22.5% CP. At 0.60% nP, adding phytase increased utilization of DM (P < 0.05) and retention of N (P < 0.10) only at 22.5% CP; P retention was not affected. In summary, microbial phytase enhanced growth performance, toe ash, ileal N and AA digestibility, and apparent N and P retention.
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Department of Animal and Poultry Sciences, Virginia Polytechnic Institute and State University, Blacksburg 24061-0306, USA.
Kornegay
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Denbow
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DM
D010832:6-Phytase / Q000494:pharmacology*; D000596:Amino Acids / Q000378:metabolism*; D000601:Amino Acids, Essential / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000378:metabolism; D004032:Diet / Q000662:veterinary*; D004063:Digestion / Q000187:drug effects* / Q000502:physiology; D005260:Female; D007082:Ileum / Q000378:metabolism / Q000502:physiology; D009584:Nitrogen / Q000378:metabolism*; D010758:Phosphorus / Q000378:metabolism; D011897:Random Allocation; D013025:Glycine max / Q000378:metabolism*; D014422:Turkeys / Q000378:metabolism* / Q000502:physiology; D003313:Zea mays / Q000378:metabolism*
D000596:Amino Acids; D000601:Amino Acids, Essential; D010758:Phosphorus; D010832:6-Phytase; D009584:Nitrogen; D002118:Calcium