Effect of omega-3 polyunsaturated fatty acid supplementation on oxidative stress parameters and sex hormone levels of modern genotype sows.

BACKGROUND: Sows are exposed to severe stress and hormonal challenges during their whole productive life. As polyunsaturated fatty acids play an important role in immune and reproductive functions, with a better understanding of their role in breeding sows' nutrition, improved performance and more sustainable pig production can be achieved. OBJECTIVES: In this study, we investigated the effects of omega-6 and omega-3 fatty acid supplementation on the antioxidant status and hormone levels of sows. METHODS: A total of 48 Danish Large white × Danish Landrace sows were supplemented either with sunflower oil (SO) as a control group or with fish oil (FO) as experimental group at the same dose of 10 g/kg feed. Blood samples were collected on day 14 of lactation, 5 days after weaning (insemination), and 30 days after insemination. To estimate antioxidant and reproductive effects, the amounts of reduced glutathione (GSH), thiobarbituric acid reactive substance, the activity of glutathione peroxidase (GPx), serum 17ß oestradiol (E2), progesterone (P4), and 6-keto prostaglandin F1α (6-keto PGF1α) levels were investigated. RESULTS: FO-based supplementation increased GPx activity on day 14 of lactation. Five days after weaning, the concentration of GSH in FO-fed sows was significantly higher than that in SO-fed sows. The E2 content of blood was significantly lower in the experimental group than in the control group for two of the three examined periods (day 14 of lactation and 30 days after insemination), whereas P4 levels were significantly higher in the experimental group 5 days after weaning. We found that 6-keto PGF1α levels were systematically lower in the experimental group throughout the trial. CONCLUSIONS: This study provides evidence of the major impact of omega-6 and -3 fatty acids on the tested hormone levels, which serve as precursors for the production of E2 and P4 but have an opposite effect on PGF2α production.

Review: Practical Use of n-3 Fatty Acids to Improve Reproduction Parameters in the Context of Modern Sow Nutrition.

The effects of long-chain polyunsaturated fatty acids (LC PUFAs) have been frequently investigated in sows because the profitability of pig production depends mainly on reproduction performance. In feeding trials, different sources and doses of n-3 PUFAs-rich feeds were used with various breeds and stages of production; however, a discrepancy in the response of n-3 PUFAs on sow reproduction has been observed. According to the results of the previous studies, n-3 fatty acids can postpone the time of parturition, decreasing the synthesis of prostaglandins, which are necessary for uterus contraction during labour. These effects could also be useful during the post-weaning period when low prostaglandin levels are indispensable for embryo survival. The n-3 fatty acids fed during the lactation period secreted in milk, may improve piglet performance. In this review, we will focus on the contradictory results of previous studies concerning practical swine nutrition. The main purpose of the review is to highlight those periods of swine breeding when the use of n-3 fatty acids may be advantageous in case of the deficiency of these essential nutrients. In finding the appropriate dose of n-3 PUFAs in terms of sow nutrition, the n-6 PUFAs levels in the given feeds must be taken into account to ensure that there are no significant reductions in the final n-6/n-3 ratio. Despite the numerous previous field trials, there are no current feeding recommendations available for PUFAs in swine nutrition. Hence, more research is required in different practical feeding situations to certify the assumptions and conclusions of this review.