title: Effect of crude protein and phosphorus level on growth performance, bone mineralisation and phosphorus, calcium and nitrogen utilisation in grower-finisher pigs.
abstract: Two experiments in a 2 x 2 factorial arrangement were conducted to evaluate the effect of crude protein (CP) (130 vs. 200 g/kg) and phosphorus (P) (4.0 vs. 6.0 g total P/kg) level in a phytase supplemented diet (500 FTU [phytase units]/kg) in grower-finisher pigs. Owing to the design of the experiment, as dietary P level increased, there was also an increase in dietary calcium (Ca) level in order to maintain a dietary Ca to P ratio of 1.6:1. In Experiment 1, four diets were fed to 56 pigs (n = 14, initial body weight [BW] 36.7 +/- 4.2 kg) to investigate the interaction between CP and P on growth performance, bone mineralisation and digesta pH. Experiment 2 consisted of 16 entire male pigs (n = 4; offered identical diets to that offered in Experiment 1) for the determination of total tract apparent digestibility and nitrogen (N), P and Ca utilisation. There was an interaction between CP and P level on bone ash, bone P and bone Ca concentrations (p < 0.05). Pigs offered low CP-low P diets had a higher bone ash, P and Ca concentrations than pigs offered high CP-low P diets. However, there was no effect of CP level at high P levels on bone ash, P and Ca concentrations. Pigs offered low P diets had a lower ileal pH compared with pigs offered high P diets (p < 0.05). In conclusion, offering pigs a high CP-low P, phytase-supplemented diet resulted in a decrease in bone mineralisation.
authors.affiliation: School of Agriculture, Food Science and Veterinary Medicine, University College Dublin, Newcastle, Ireland.
authors.forename: Patrick F
authors.initials: PF
authors.lastname: Varley
authors.forename: Bernie
authors.initials: B
authors.lastname: Flynn
authors.forename: James J
authors.initials: JJ
authors.lastname: Callan
authors.forename: John V
authors.initials: JV
authors.lastname: O'Doherty
mesh_terms: D000818:Animals; D015519:Bone Density / Q000187:drug effects* / Q000502:physiology; D002118:Calcium / Q000378:metabolism*; D004044:Dietary Proteins / Q000494:pharmacology*; D005260:Female; D008297:Male; D009584:Nitrogen / Q000378:metabolism*; D010758:Phosphorus / Q000378:metabolism; D016226:Phosphorus, Dietary / Q000378:metabolism / Q000494:pharmacology*; D013552:Swine / Q000254:growth & development / Q000378:metabolism*; D015430:Weight Gain
chemical_list: D004044:Dietary Proteins; D016226:Phosphorus, Dietary; D010758:Phosphorus; D009584:Nitrogen; D002118:Calcium