Effect of dietary phosphorus and genetic background on carcass characteristics, meat quality and gene expression in porcine muscle

Dietary phosphorus (P) is essential for growth; however, environmental concerns have led to attempts to reduce P levels in pig diets. The objective of this study was to determine the effects of genetics, dietary P and their interaction on carcass traits, meat quality and gene expression in muscle. Gilts (n=96, 3 wk old), sired by 2 sire lines (PIC337 and PIC280), were fed either a P adequate (PA) or a 20% P deficient (PD) diet for 14wk. At trial end, carcass traits, meat quality and gene expression in muscle were determined. Pigs fed PD had lower (p<0.05) live weight, hot carcass weight (HCW), % fat-free lean (FFL), and loin marbling, and tended to have higher (p<0.12) depth of rib fat than PA fed pigs. Pigs fed PD tended to have lower (p<0.1) IGFBP2, and higher oxytocin receptor (OXTR) mRNA than PA fed pigs. PIC337 sired pigs had higher (p<0.05) HCW, loin muscle area, and tended to have higher (p<0.07) FFL and lower total glucose in loin muscle than their PIC280 sired counterparts. PIC337 pigs had higher levels (p<0.1) of glycogen glucotransferase, succinate dehydrogenase Fe/S protein, lactate dehydrogenase and IGFBP2 mRNA, but less (p<0.1) OXTR mRNA than PIC280 sired pigs. Our data demonstrate that P and genetics impact carcass characteristics, meat quality and gene expression in muscle. These data may lead to strategies to increase the efficiency of growth in pigs in a more environmentally friendly manner.