Effects of feeding whole crop rice combined with soybean oil on growth performance, carcass quality characteristics, and fatty acids profile of Longissimus muscle and adipose tissue of pigs

Abstract

This study was conducted to determine the effects of soybean oil supplementation on growth performance, carcass characteristics and fatty acids composition in muscle and adipose tissue of pigs fed on whole crop rice (WCR, variety bc1). Forty-eight pigs (Duroc × Landrace × Yorkshire, 36 kg) were randomly assigned to four treatments with three replications each. The diets included the ground WCR at levels of 0, 8, 12 or 16% and supplemented with soybean-oil at levels of 0, 2, 3 and 4 %, accordingly replacing the maize, and designated as control C, T1, T2 and T3, respectively. All pigs at about 90 kg were slaughtered to determine carcass quality and fatty acid composition. In growing period, the daily feed intake was significantly lower for pigs fed the diets containing WCR than for those on the control diets. The pigs on T3 diet had significantly lower average daily gain (735 g/day) than those on C (806 g/day), T1 (808 g/day) or T2 (827 g/day) diets ( P < 0.05). The feed conversion ratio was significantly lower in pigs on T1 (2.79) or T2 (2.72) diets than on the control (2.98) ( P < 0.05). No significant difference was found in daily feed intake, average daily gain and feed conversion ratio among pigs on different diets in finishing period ( P > 0.05). The carcass characteristics did not differ among different treatments ( P > 0.05). The water holding capacity of loin muscle was significantly lower for pigs fed diets containing WCR than for those on the control ( P < 0.05). There were no significant differences in meat color, marbling, pH and cooking loss among pigs on different diets. The concentration of saturated fatty acid (SFA) and monounsaturated fatty acid (MUFA) in back fat decreased significantly with the inclusion of soybean oil in the diet ( P < 0.05). The same trend was showed in Longissimus muscle, and SFA in T1 and MUFA in T3 were significantly lower than those in the control ( P < 0.05), respectively. The polyunsaturated fatty acid (PUFA), n-6 PUFA and n-3 PUFA were significantly higher in the Longissimus muscle and backfat of pigs fed diet with soybean oil and WCR than those in the control ( P < 0.05). The Longissimus muscle and back fat of pigs fed the diet with soybean oil and WCR were significantly higher in PUFA/SFA and lower in n-6/n-3 ratio than those of the control ( P < 0.05), with exception of the ratio of n-6/n-3 in muscle for T1. The study suggests that whole crop rice could be used as a feed ingredient for growing-finishing pigs with soybean-oil supplementation and that the treatment including soybean oil would improve the fatty acid profile of the carcass as food for humans.