Effects of dietary inclusion of soy oil on growth performance, carcass characteristics, serum metabolites, hormones and meat quality in finishing pigs

High levels of polyunsaturated fatty acids (PUFA) in pork are beneficial and saturated fatty acids (SFA) detrimental to human health. Inclusion of PUFA in diet may decrease the amount of intramuscular fat (IMF) due to inhibition of de nova synthesis of fatty acids, which has a negative effect on meat eating quality. Diet energy level is a leading factor for lipid deposition in IMF. We hypothesize that increasing dietary energy level by including PUFA will increase its content without decreasing IMF in meat, thus increasing meat's nutritional value without lowering meat eating quality. The results of this study showed that increasing dietary energy level by inclusion of soy oil decreased average daily feed intake (ADFI) (P<0.01) and feed:gain ratio (P<0.01), increased average daily weight gain ADG (P<0.05) and serum triglyceride concentration (P<0.05) and decreased serum urea concentration (P<0.05). Carcass characteristics, meat quality and serum concentrations of hormones [insulin, growth hormone (GH), insulin-like growth factor-I (IGF-I), glucagon and tumor necrosis factor-alpha (TNF-alpha)] were unaffected. Percentages of SFA and monounsaturated fatty acids (MUFA) were decreased while percentages of PUFA were increased (P<0.05) in longissimus dorsi (LD) muscle as dietary energy level increased. The results of this study suggested that increasing dietary energy level by inclusion of soy oil could be a suitable way to improve growth performance as well as nutritional value of pork without lowering eating quality.