CHAPTER 2: Use of CLA in Animal Feed

Conjugated linoleic acids (CLA) are reputed to have health-promoting properties and it is therefore of interest to enrich food and feed ingredients with CLA. This chapter provides a comprehensive review of published studies on dietary CLA supplementation on zootechnical and reproductive performance, tissue and product (milk, egg) CLA enrichment and fatty acid profile, and immune status of livestock:ruminants (diary and meat-type), pigs, poultry (laying and meat-type) and some fish species. It is clear that CLA supplementation to these livestock species results in elevated concentrations of both cis-9, trans-11 and trans-10, cis-12 CLA isomers in body tissues and products (milk, eggs) with a concomitant increase and decrease in saturated and unsaturated fatty acids, respectively. With maybe the exception of a strong trend towards a decreased body fat deposition and product fat content, the effects of CLA on other zootechnical and reproductive performance characteristics, and immune functioning are highly variable between the published studies, and this variability holds for all investigated livestock species. Possible causes for these inconsistent results are discussed.