title: Efficacy of supplemental microbial phytase at different dietary calcium levels on growth performance and mineral utilization of broiler chickens.
abstract: A 3-wk feeding trial with 240 sexed, day-old broiler chickens was conducted to determine the efficacy of microbial phytase at different levels of dietary Ca on performance and utilization of minerals in broiler chickens fed a low-P corn-soybean diet. The experimental design was a 3 x 2 factorial arrangement of treatments; Ca at 0.6, 1.0, and 1.25% and phytase at 0 and 600 phytase U/kg diet. Phytase supplementation, regardless of Ca level, increased (P < or = 0.005) feed intake, (P < or = 0.0001) body weight, and (P < or = 0.025) feed efficiency at 21 d; the optimum levels of body weight, feed intake, and feed efficiency were obtained with low (0.6%) dietary Ca plus phytase. Retentions of P, Ca, and N were increased (P < or = 0.05) by phytase supplementation. Although maximum retentions of P and N were obtained at the 1.0 and 1.25% Ca levels, respectively, they were not significantly different from the values obtained at 0.6% Ca. The increasing level of dietary Ca decreased plasma P ( P < or = 0.05) and Cu (P < or = 0.06). Phytase supplementation had the opposite effect; i.e., increased plasma P (P < or = 0.03) and Cu (P < or = 0.02). The maximum level of plasma P was obtained with phytase at the 1.0% Ca level, but this value was not significantly different from the value obtained with phytase at the 0.6% Ca level. Phytase supplementation increased (P < 0.04) the ash content of both tibia head and shaft but had no effect on mineral contents in the ash. The optimum level of ash content was observed with the 0.06% Ca diet plus phytase. The results show that microbial phytase supplementation to a low P diet improved growth performance and mineral utilization in broiler chickens. Dietary Ca levels had a significant effect on the response to phytase; the optimum growth performance and mineral utilization were achieved at the low (0.6%) level of dietary Ca supplemented with phytase.
authors.affiliation: Department of Animal Science, Macdonald Campus of McGill University, Quebec, Canada.
authors.forename: S
authors.initials: S
authors.lastname: Sebastian
authors.forename: S P
authors.initials: SP
authors.lastname: Touchburn
authors.forename: E R
authors.initials: ER
authors.lastname: Chavez
authors.forename: P C
authors.initials: PC
authors.lastname: Laguë
mesh_terms: D010832:6-Phytase / Q000008:administration & dosage / Q000494:pharmacology*; D000704:Analysis of Variance; D000818:Animals; D001842:Bone and Bones / Q000187:drug effects / Q000378:metabolism; D002136:Calcium, Dietary; D002645:Chickens; D004734:Energy Metabolism / Q000187:drug effects; D005163:Factor Analysis, Statistical; D005247:Feeding Behavior / Q000187:drug effects*; D005260:Female; D005527:Food, Fortified; D008297:Male; D008903:Minerals / Q000378:metabolism*; D012727:Sex Characteristics; D014131:Trace Elements / Q000378:metabolism*; D015430:Weight Gain / Q000187:drug effects*
chemical_list: D002136:Calcium, Dietary; D008903:Minerals; D014131:Trace Elements; D010832:6-Phytase