The Effect of Conjugated Linoleic Acid on Fat to Lean Repartitioning and Feed Conversion in Pigs

Michael E.R. Dugan, J.L. Aalhus and A.L. Schaefer

Agriculture and Agri-Food Canada, Research Centre, 6000 C&E Trail Lacombe, AB, Canada, T4L 1W1

Conjugated linoleic acid (CLA) is a collective name for a group of geometric and positional isomers of linoleic acid in which the constituent double bonds are separated by a single carbon-carbon bond instead of a methylene group. Conjugated linoleic acid has recently been reported to have potent fat to lean repartitioning and feed efficiency improving effects in rats (Chin et al. 1994). In addition, CLA has been shown to stimulate the immune system (Cook et al. 1993) and protect against artherosclerosis (Lee et al. 1994) and chemically induced breast cancer (Ip et al. 1996). As a result, there is considerable interest in including CLA in animal feed to both improve lean production efficiency and provide value-added healthful meat products for human consumption. The objective of the present study was to compare the growth performance and carcass composition of pigs fed diets supplemented with either CLA or sunflower oil (the oil used for CLA manufacture).

One hundred and eight pigs (54 gilts and 54 barrows) were fed one of two experimental diets from 61.5 to 106 kg live weight. Diets were barley/wheat/soybean/canola based and contained either 2% CLA or 2% sunflower oil. Irrespective of gender, pigs fed CLA tended to have reduced feed intakes (-5.2%, P = 0.07), improved feed conversion efficiencies (-5.9%, P = 0.06) and similar rates of gain relative to sunflower oil fed pigs. In addition, pigs fed CLA deposited less subcutaneous fat (-6.8%, P = 0.01) and gained more lean (+2.3%, P = 0.03) than pigs fed sunflower oil.

Implication: These data suggest CLA can be used as a repartioning agent in pigs. Ongoing research is directed toward optimizing repartitioning for maximum economic return.