title: Lowering the dietary calcium to total phosphorus ratio increases phosphorus utilization in low-phosphorus corn-soybean meal diets supplemented with microbial phytase for growing-finishing pigs.
abstract: Crossbred growing-finishing pigs (n = 120) were used to investigate the effect of three dietary Ca:total P (tP) ratios (1.5:1, 1.3:1, or 1.0:1) on P utilization in low-P corn-soybean meal diets supplemented with microbial phytase at 500 phytase units/kg. The basal grower (23 to 54 kg BW) diet contained .39% tP including .07% added inorganic P (iP), and the basal finisher (54 to 123 kg BW) diet contained .32% tP without added iP. An adequate-P positive control diet without phytase supplementation contained .60% Ca and .50% tP during the growing phase and .50% Ca and .40% tP during the finishing phase. Lowering the Ca:tP ratio linearly increased ADG during the growing phase (P < .03) and overall (P < .08), gain:feed ratio during the growing phase (P < .001), and P absorption during the finishing phase (P < .04). Lowering the Ca:tP ratio linearly increased BW at slaughter (P < .02), carcass weight (P < .04), bone breaking strength (P < .04), and bone ash weight (P < .06), whereas dressing percentage and backfat depth remained unchanged. In conclusion, pig performance and P utilization were increased by lowering the Ca:tP ratio from 1.5:1 to 1.0:1 in low-P corn-soybean meal diets supplemented with microbial phytase.
authors.affiliation: Department of Animal Sciences, University of Missouri, Columbia 65211, USA.
authors.forename: J
authors.initials: J
authors.lastname: Liu
authors.forename: D W
authors.initials: DW
authors.lastname: Bollinger
authors.forename: D R
authors.initials: DR
authors.lastname: Ledoux
authors.forename: T L
authors.initials: TL
authors.lastname: Veum
mesh_terms: D010832:6-Phytase / Q000008:administration & dosage*; D000821:Animal Feed; D000818:Animals; D001823:Body Composition; D001824:Body Constitution; D002136:Calcium, Dietary; D005527:Food, Fortified; D010758:Phosphorus / Q000378:metabolism; D013025:Glycine max; D013552:Swine / Q000254:growth & development*; D015430:Weight Gain; D003313:Zea mays
chemical_list: D002136:Calcium, Dietary; D010758:Phosphorus; D010832:6-Phytase