title: The effects of dietary calcium, phosphorus, and protein on the performance and nutrient utilization of broiler chickens.
abstract: The effects of varying dietary Ca, available phosphorus (AP), and protein on 5- to 17-day performance (growth and feed efficiency), Ca and P contents of tibia and plasma, ME, and N utilization of broiler chickens were investigated in three experiments. In Experiment 1, high dietary Ca (24.3 versus 11.8 g/kg) reduced performance, N digestibility, and ME, whereas N retention was not affected. Reducing dietary protein (186 or 203 versus 217 g/kg) reduced performance and N retention but increased ME. In Experiment 2, high dietary Ca (25.3 versus 10.7 g/kg) reduced performance, tibia Ca, and plasma P and increased plasma total Ca; whereas the diet with both high Ca (25.3 g/kg) and high AP (9.8 versus 4.3 g/kg) reduced only performance. Reducing dietary protein from 206 to 166 g/kg diet reduced growth but improved feed efficiency and tibia P content. In Experiment 3, a diet containing 25.6 g of Ca and 4.9 or 10.7 g of AP compared with a diet containing 11.2 g of Ca and 4.9 g of AP/kg of diet reduced performance. Reducing dietary protein from 236 to 215 g/kg of diet decreased performance. It was concluded that high dietary Ca reduced growth performance and feed efficiency and that altering the dietary protein from 166 to 236 g/kg of diet did not overcome the growth depression effect of high Ca or of high Ca and AP diets.
authors.affiliation: Department of Farm Animal Medicine and Production, University of Queensland, St. Lucia, Australia.
authors.forename: T M
authors.initials: TM
authors.lastname: Shafey
authors.forename: M W
authors.initials: MW
authors.lastname: McDonald
mesh_terms: D000818:Animals; D002118:Calcium / Q000032:analysis / Q000097:blood; D002136:Calcium, Dietary / Q000008:administration & dosage / Q000494:pharmacology*; D002645:Chickens / Q000254:growth & development* / Q000378:metabolism; D004044:Dietary Proteins / Q000008:administration & dosage / Q000494:pharmacology*; D004435:Eating / Q000187:drug effects; D009584:Nitrogen / Q000378:metabolism; D010758:Phosphorus / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D013977:Tibia / Q000737:chemistry; D015430:Weight Gain / Q000187:drug effects
chemical_list: D002136:Calcium, Dietary; D004044:Dietary Proteins; D010758:Phosphorus; D009584:Nitrogen; D002118:Calcium