Compensatory effect of dietary phosphorus on performance of growing pigs and development of bone mineral density assessed using dual energy X-ray absorptiometry

Abstract Two experiments were conducted using nursery and grower–finisher pigs and dual energy X-ray absorptiometry to monitor the ability of pigs to compensate in area bone mineral density (aBMD; g/cm 2 ) in response to the levels of dietary digestible P following a period of P insufficiency. In experiment 1, 48 female pigs were selected at 8.1 ± 1.0 kg and individually allocated to one of four treatments. The treatments were: high–high (HH) digestible P (3.7 g digestible P/kg for 28 days followed by 3.5 g digestible P/kg for 28 days); high–low (HL) digestible P (3.7 g digestible P/kg for 28 days followed by 2.5 g digestible P/kg for 28 days); low–high (LH) digestible P (3.0 g digestible P/kg for 28 days followed by 3.5 g digestible P/kg for 28 days); and low–low (LL) digestible P (3.0 g digestible P/kg for 28 days followed by 2.5 g digestible P/kg for 28 days). The aBMD was measured at days 0, 28 and 56. In experiment 2, 32 female pigs were selected at 34.0 ± 2.0 and individually allocated to one of four treatments until slaughter at about 102 ± 2 kg live weight. The treatments were: HH digestible P (2.8 g digestible P/kg fed for 35 days followed by 2.3 g digestible P/kg fed to slaughter); HL digestible P (2.8 g digestible P/kg diet fed for 35 days followed by 1.6 g digestible P/kg fed to slaughter); LH digestible P (1.6 g digestible P/kg fed for 35 days followed by 2.3 g digestible P/kg fed to slaughter); and LL digestible P (1.6 g digestible P/kg fed for 35 days followed by 1.6 g digestible P/kg fed to slaughter). The pigs were scanned at days 0, 35 and 70, and a third metacarpal was collected at slaughter for analysis. At day 56 in experiment 1 the left and right hind aBMD was higher (P