There is interest in the enrichment of poultry meat with long-chain omega-3 (n-3) polyunsaturated fatty acids in order to increase the consumption of these fatty acids by humans. However, there is concern that high levels of n-3 polyunsaturated fatty acids may have detrimental effects on immune function in chickens, according to H. Al-Khalifa of the Kuwait Institute for Scientific Research in Safat and co-authors at the UK's University of Reading in a paper published in the current issue of Poultry Science.

The effect of feeding increasing levels of fish oil (FO) on immune function was investigated in broiler chickens. Three-week-old broilers were fed one of four wheat-soybean basal diets that contained 0, 30, 50 or 60g per kg of FO until slaughter.

At slaughter, samples of blood, bursa of Fabricius, spleen and thymus were collected from each bird.

A range of immune parameters, including immune tissue weight, immuno-phenotyping, phagocytosis and cell proliferation, were assessed.

The pattern of fatty acid incorporation reflected the fatty acid composition of the diet. The FO did not affect the weight of the spleen but it did increase thymus weight when fed at 50g per kg (P<0.001). Fish oil also lowered bursal weights when fed at 50 or 60g per kg (P<0.001).

There was no significant effect of FO on immune cell phenotypes in the spleen, thymus, bursa or blood.

Feeding 60g per kg of FO significantly decreased the percentage of monocytes engaged in phagocytosis but it increased their mean fluorescence intensity relative to that of broilers fed 50g per kg of FO.

Lymphocyte proliferation was significantly decreased after feeding broiler chickens diets rich in FO when expressed as division index or proliferation index, although there was no significant effect of FO on the percentage of divided cells.

Al-Khalifa and co-authors concluded that dietary n-3 polyunsaturated fatty acids decrease phagocytosis and lymphocyte proliferation in broiler chickens, highlighting the need for the poultry industry to consider the health status of poultry when poultry meat is being enriched with FO.

Reference

Al-Khalifa H., D.I. Givens, C. Rymer, and P. Yaqoob, 2012. Effect of n-3 fatty acids on immune function in broiler chickens. Poultry Science, 91:74-88. doi: 10.3382/ps.2011-01693

Further Reading

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