title: Improving phytate phosphorus availability in corn and soybean meal for broilers using microbial phytase and calculation of phosphorus equivalency values for phytase.
abstract: Two experiments were conducted to determine the effectiveness of Natuphos phytase for improving P availability of soybean meal-based semipurified diets (SP, Experiments 1 and 2) and corn-soybean meal-based diets (CS, Experiment 2) fed to broilers (1 to 21 d). There were 360 and 288 birds fed the SP diets in Experiments 1 and 2, respectively, and 288 birds were fed the CS diets in Experiment 2. Phosphorus equivalency values for phytase were calculated. The basal diets were formulated to contain 0.27% nonphytate P (nP); the SP basal diet contained 0.45% total P (tP) that included 0.17% P as defluorinated phosphate; the CS basal diet contained 0.51% tP that contained 0.12% P as defluorinated phosphate. Both basal diets were supplemented with defluorinated phosphate to provide 0.36, 0.45, of 0.54% nP or with 350, 700, or 1,050 U of phytase/kg diets. Supplementing defluorinated phosphate and phytase linearly increased BW gain (P < 0.001), feed intake (P < 0.001), and percentage ash of dried toes (P < 0.01). Phytase addition increased apparent retention of P (P < 0.02), Ca (P < 0.005 in Experiment 2), and N (P <0.06 in Experiment 2 for CS), increased apparent digestibility of DM (P < 0.04), and linearly decreased (P <0.005) P excretion. In comparison to the 0.45% np diet, P excretion was reduced 42 to 51% by addition of phytase. The addition of defluorinated phosphate linearly decreased apparent retention of P (P < 0.02) and Ca (P < 0.005 in Experiment 2), and increased P excretion (P < 0.007). The average of released P by phytase calculated by solving nonlinear or linear response equations of P and phytase levels for SP diets in Experiments 1 and 2 gave a P equivalency value 1 g P = 1,146 U of phytase. The P equivalency value for CS diets fed only in Experiment 2 was 785 U of phytase = 1 g P as defluorinated phosphate. These studies show that microbial phytase is effective for improving P availability and for decreasing P excretion. Added phytase can also increase Ca and N retention.
authors.affiliation: Department of Animal and Poultry Sciences, Virginia Polytechnic Institute and State University, Blacksburg 24061-0306, USA.
authors.forename: Z
authors.initials: Z
authors.lastname: Yi
authors.forename: E T
authors.initials: ET
authors.lastname: Kornegay
authors.forename: V
authors.initials: V
authors.lastname: Ravindran
authors.forename: D M
authors.initials: DM
authors.lastname: Denbow
mesh_terms: D010832:6-Phytase / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000032:analysis / Q000378:metabolism / Q000493:pharmacokinetics; D002645:Chickens / Q000254:growth & development / Q000378:metabolism* / Q000502:physiology; D004032:Diet / Q000592:standards / Q000662:veterinary; D004063:Digestion / Q000502:physiology; D005527:Food, Fortified; D016014:Linear Models; D008297:Male; D008954:Models, Biological; D009584:Nitrogen / Q000032:analysis / Q000378:metabolism / Q000493:pharmacokinetics; D010758:Phosphorus / Q000032:analysis / Q000378:metabolism / Q000493:pharmacokinetics*; D010833:Phytic Acid / Q000032:analysis / Q000378:metabolism / Q000493:pharmacokinetics*; D011897:Random Allocation; D013025:Glycine max / Q000737:chemistry* / Q000378:metabolism; D015430:Weight Gain / Q000502:physiology; D003313:Zea mays / Q000737:chemistry* / Q000378:metabolism
chemical_list: D010758:Phosphorus; D010833:Phytic Acid; D010832:6-Phytase; D009584:Nitrogen; D002118:Calcium