Effect of dietary rapeseed and soybean oil on growth performance, carcass traits, and fatty acid composition of pigs

The objectives of this investigation were to examine the impact of the dietary inclusion of rapeseed and soybean oil and the length of their feeding before slaughter on growth performance, quantitative and qualitative carcass traits, and fatty acid composition in longissimus lumborum muscle (LLM) of pigs. The experiment was conducted with 72 pigs (36 barrows and 36 gilts), divided into six oil-containing diet groups and one control group. Diets of the experimental groups were supplemented with 4% rapeseed (ROD) or soybean (SOD) oil for six, four, and two weeks before slaughter. Diet of the control group had no oil supplement. Animals were fed ad libitum and slaughtered at average body weight of 115.8 kg. The oil supplement and feeding duration had a significant effect on fatty acid composition in intramuscular fat of LLM. The diet with both rapeseed and soybean oil significantly increased the content of linoleic acid and α-linolenic acid (ALA) in intramuscular fat. Both types of oil significantly increased total PUFA, n-3 PUFA, and the PUFA:SFA ratio. The significant decrease of n-6:n-3 PUFA ratio was observed in groups fed rapeseed oil for four and six weeks. Dietary addition of oils did not have any significant effect on average daily gain, carcass traits, and physical characteristics of LLM of pigs. However, daily feed intake and feed conversion ratio were reduced in the groups with soybean oil supplement. The results show that rapeseed oil supplementation (two weeks before slaughter) has positive effect on n-6:n-3 PUFA ratio and increase of ALA without negative effect on meat and fat quality.