title: Digestible phosphorus needs of terminal-cross growing-finishing pigs.
abstract: Growth and digestion experiments were conducted to estimate the digestible P needs of terminal-cross growing-finishing pigs fed sorghum-soybean meal-based diets from 25 to 118 kg. Dietary available P levels approximated the levels recommended by the NRC (1988) or were approximately 25% above or below those levels. Up to 80 kg, dietary treatment did not affect performance; from 80 to 118 kg, the lowest P level (no inorganic P) reduced (P = .03) feed efficiency. Carcass leanness, subjective quality scores for the loin, chemical content of lean, and sensory evaluation of cooked lean were not adversely affected by decreasing P. As dietary P decreased, connective tissue amount in the lean decreased (P = .06). Ash content (P < .01) and peak load (P < .05) of metacarpals and metatarsals decreased as dietary P decreased, but structural soundness scores in the live pig were unaffected by treatment. Apparent digestibility of P decreased (P = .08 to P < .01) as dietary P decreased in the diets. Estimated P excretions per pig decreased with decreasing dietary P up to 80 kg; during the 80-to-118-kg interval, P excretions were similar for pigs fed the two lowest P diets due to reduced feed efficiency of pigs fed the lowest P diet. Dietary digestible P contents maximizing performance and carcass merit were .21, .19, and .16% for pigs fed from 25 to 50, 50 to 80, and 80 to 118 kg, respectively. The results suggest that P excretions of terminal-cross pigs can be reduced by feeding less than current NRC recommendations for P without reducing performance, carcass merit, or structural soundness of live pigs.
authors.affiliation: Department of Animal Science, Texas A&M University, College Station 77843, USA.
authors.forename: P R
authors.initials: PR
authors.lastname: O'Quinn
authors.forename: D A
authors.initials: DA
authors.lastname: Knabe
authors.forename: E J
authors.initials: EJ
authors.lastname: Gregg
mesh_terms: D000818:Animals; D001823:Body Composition / Q000187:drug effects / Q000502:physiology; D001842:Bone and Bones / Q000737:chemistry / Q000378:metabolism; D004032:Diet / Q000662:veterinary; D004063:Digestion / Q000187:drug effects / Q000502:physiology*; D005260:Female; D005524:Food Technology; D008297:Male; D008460:Meat / Q000592:standards; D009751:Nutritional Requirements; D010758:Phosphorus / Q000032:analysis / Q000378:metabolism* / Q000494:pharmacology*; D016226:Phosphorus, Dietary / Q000592:standards; D013552:Swine / Q000254:growth & development* / Q000378:metabolism / Q000502:physiology*
chemical_list: D016226:Phosphorus, Dietary; D010758:Phosphorus