Responses of growing pigs to different levels of dietary phosphorus — Performance, bone characteristics, and solubility of faecal phosphorus
2010
Partanen, Kirsi | Siljander-Rasi, Hilkka | Karhapää, Maija | Ylivainio, Kari | Tupasela, Tuomo
A performance trial was carried out with 117 growing barrows (25-65kg) to study the effects of different levels of dietary phosphorus (P) on the pigs' performance and bone characteristics and on the content and solubility of P in faeces. Isoenergetic diets (9.0MJNEkg⁻¹) were used containing 0.10, 0.55, 1.00, 1.45, 1.90, and 2.35% of monocalcium phosphate, and a constant calcium (Ca) to P ratio of 1.2:1. The analysed total P content ranged from 4.1 to 9.5gkg⁻¹. The diets were calculated to contain 1.6, 2.5, 3.5, 4.5, 5.5, to 6.5gkg⁻¹ of nonphytate P, respectively. The diet with the lowest nonphytate P content resulted in slightly lower average daily gain than the diets with ≥2.5gkg⁻¹ of nonphytate P. The feed to gain ratio was increased when the diets contained more than 3.5gkg⁻¹ of nonphytate P. The bending moment of rib and metacarpal bones was increased until the nonphytate P content reached 4.5 and 2.5gkg⁻¹ feed, respectively, while 4.5gkg⁻¹ of nonphytate P was required to maximise the Ca and P content of metacarpals. In accordance with the Hedley fractionation, the amount of water-soluble P was not affected by increased dietary phosphate content, but the amounts of NaHCO₃-, NaOH-, and HCl-soluble P fractions increased. In conclusion, the nonphytate P content of 2.5gkg⁻¹ feed was recommended for growing pigs of 25-65kg body weight.
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