Recent advances in the use of fatty acids as supplements in pig diets : a review

The lipids in feed commonly fed to pigs consist mainly of neutral fats (specifically triglycerides), esters of fatty acids and glycerol. The degree of unsaturation, the length of the carbon chains and the isomeric form of the fatty acids greatly influence both the physical and chemical characteristics of fat. In swine nutrition, fats are traditionally introduced in diets as a high-energy constituent; moreover, they also supply liposoluble vitamins and essential fatty acids. In addition, the efficiency of using metabolisable energy from lipids is very high, with a minimum heat increment compared to the other nutrients. Recently, nutritionists have become interested in specific fatty acids for their potentially beneficial physiological effects on metabolism in the intestinal mucosa, and anti-microbial, anti-inflammatory and immunomodulatory activity and functional food design. The following are examples of fatty acids that show these favourable effects: short- and medium-chain fatty acids, omega-3 fatty acids conjugated linoleic acid, and they will form the basis of this review.