title: Growth performance, diet nutrient digestibility, and bone mineralization in weaned pigs fed pelleted diets containing thermostable phytase.
abstract: Traditional supplemental dietary phytase loses activity during steam pelleting. The thermal tolerance and bioefficacy of a phytase product with a thermoprotective coating [coated phytase (C-phytase)] was compared in mash and pelleted diets to a traditional, uncoated phytase (U-phytase) added to a negative control (NC) diet, formulated with reduced dietary Ca and P, and compared with a corn-soybean meal based positive control (POC) diet. Growth performance, nutrient digestibility, and third metacarpal bone characteristics were response variables. Weaned pigs (n = 56; 8.20 ± 0.5 kg initial BW; 28 d of age) were individually housed and randomly allotted to 1 of 7 diets for 21 d. The diets were 1) POC mash, 2) NC mash, 3) NC pelleted at 90°C, 4) NC mash + 500 U/kg U-phytase, 5) NC mash + 500 U/kg C-phytase, 6) NC + 500 U/kg C-phytase pelleted at 80°C, and 7) NC + 500 U/kg C-phytase pelleted at 90°C. The POC and NC diets were formulated to be isoenergetic and isolysinic. The content of Ca and available P was 1.01 and 0.40% and 0.83 and 0.22% in the POC and NC diets, respectively. Pig BW and feed intake were measured on d 7, 14, and 21, and feces were collected for 2 d. On d 21, pigs were killed and ileal digesta and the third metacarpal bone collected. Pigs fed POC had greater (P < 0.05) ADG, G:F, P digestibility, and bone mineralization but lower (P < 0.01) energy digestibility than pigs fed NC. Pelleting the NC diet did not improve performance, nutrient digestibility, or P use. Adding the U-phytase to NC mash diet increased (P < 0.05) ADG, G:F, apparent ileal digestibility (AID) of CP and Ile, Leu, Phe, Thr, Val, and Ser, and apparent total tract digestibility (ATTD) of P compared with pigs fed NC. Pigs fed C-phytase in NC mash diets had increased (P < 0.05) G:F and an AID of CP and AA and ATTD of P compared with pigs fed NC but not different than pigs fed U-phytase NC mash diets. Pigs fed pelleted NC diet with C-phytase had a greater (P < 0.05) ATTD of P and energy than pigs fed mash NC diet with C-phytase but had similar growth performance, AID of CP and AA, and bone mineralization to pigs fed U-phytase. In conclusion, release and bioefficacy of phytase after pelleting was not affected by the thermal protective coating.
authors.affiliation: Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, Alberta T6G 2P5, Canada.
authors.forename: J L
authors.initials: JL
authors.lastname: Yáñez
authors.forename: J L
authors.initials: JL
authors.lastname: Landero
authors.forename: A
authors.initials: A
authors.lastname: Owusu-Asiedu
authors.forename: M
authors.initials: M
authors.lastname: Cervantes
authors.forename: R T
authors.initials: RT
authors.lastname: Zijlstra
mesh_terms: D010832:6-Phytase / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D000596:Amino Acids / Q000378:metabolism; D000821:Animal Feed / Q000032:analysis*; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D002113:Calcification, Physiologic / Q000187:drug effects; D002118:Calcium / Q000378:metabolism; D004032:Diet / Q000662:veterinary*; D004063:Digestion / Q000502:physiology*; D007082:Ileum / Q000502:physiology; D010758:Phosphorus / Q000378:metabolism; D013552:Swine / Q000254:growth & development* / Q000502:physiology*
chemical_list: D000596:Amino Acids; D010758:Phosphorus; D010832:6-Phytase; D002118:Calcium