Modulatory effects of omega-3 polyunsaturated fatty acids on milk fatty acid composition and dairy goats immune response

There is a general view that ω-3 PUFAs are beneficial in human diseases. Due to these positive effects and to the fact that milk fat of ruminants contains a low level of PUFAs and a relatively high proportion of saturated fatty acids, feeds rich in ω-3 PUFAs are used in dairy ruminant nutrition to enhance the EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) contents in milk. Moreover ω-3 fatty acids could modulate immune response in dairy ruminants since ω-3 PUFAs reduce tissue levels of the mmunosuppressive agents arachidonic acid and prostaglandin E2 We found that in colostrum, fish oil supplementation of dairy goats diet lowered the proportions of C18:0, C18:2, C18:3 and elevated those of C16:1 and very long-chain ω−3 PUFAs, mainly EPA and DHA. In mature milk, fish oil supplementation lowered the proportion of C18:0 and raised C16:1 and ω−3 PUFAs (C18:3, EPA and DHA). Estimated transfer efficiencies for EPA and DHA into mature milk were 14 and 7%, respectively. Supplementation of dairy goats diets with fish oil enhanced also the content of cis-9,trans-11 CLA in milk fat from 0.6% to 1.93%. In vitro the phagocytic activity in goat polymorphonuclear leukocytes was significantly increased by EPA and DHA, while DHA significantly downregulated the production of Reactive Oxygen Species (ROS). Moreover always in vitro studies EPA and DHA showed important and specific roles in modulating monocyte immune functions. The administration of fish oil to dairy goats in transition appeared to affect the variation in blood leukocytes with a constant increase in CD4- and CD8-positive cells in comparison with an isocaloric and isoproteic fat-enriched palm oil supplemented diet. In conclusion goat’s colostrum and milk can be enriched in n−3 PUFAs and CLA by maternal dietary fish oil supplementation during late gestation and early lactation, moreover EPA and DHA have important and specific roles in modulating immune functions. These results support use of fat sources rich in n−3 PUFAs in goats diets not only to increase the nutritional value of milk for human consumption, but also because they can improve animal health.