The relationship between dietary fat sources and immune response in poultry and pigs: An updated review

• The effects of dietary oils on the functions of immune cells in poultry and pigs are reviewed.
• Rich sources of n-3 PUFA can have a modulating influence on immune cells.
• This modulating effect is not always reflected in improved performance.

The aim of this review paper is to present and discuss the current experimental findings describing the effects of dietary oils on the functions of immune cells and the efficacy of different mechanisms of the immune system in poultry and pigs. The majority of experiments of this kind have focussed on dietary sources of n-3 polyunsaturated long-chain fatty acids (n-3 PUFAs). Their results have shown a significant association between dietary fat (i.e., the level of n-3 PUFAs as well as n-6:n-3 PUFAs ratio in the diet) and different mechanisms of immune response. Dietary supplementation with rich sources of n-3 PUFAs, especially with fish oil, can have a beneficial, modulating influence on the immune system; specifically they appear to decrease acute and chronic inflammatory immune reactions and simultaneously to improve indices of specific immune response. However, several studies demonstrated that anti-inflammatory properties of n-3 PUFAs do not always result in improvement of growth or egg performance.