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Fish oil has been recognized as a good dietary source of n-3 long-chain polyunsaturated fatty acids (PUFA). Long-chain PUFAs, such as 20:5n-3 (EPA), 22:6n-3 (DHA), 22: 5n-3 (DPA) and 20:4n-6 (ARA), play an important role in fetal growth and development. Moreover, it was hypothesized that the supplementation of fish oil in sow diet might regulate the metabolism of n-3 LC-PUFA in the placenta and livers of piglets. Therefore, the present study was designed to assess two objectives. The first objective was to examine the effect of fish oil supplementation on the fatty acid composition of the red blood cells (RBC) of sows and their piglets, placenta, milk and livers of piglets. The second objective was to examine the effect of fish oil in sow diet on the mRNA expression of fatty acid desaturase genes in the placenta and livers of piglets. For that purpose, a total of 16 second-parity sows were allocated equally into two groups. Sows were fed either a soybean oil diet (SD) or a soybean oil + fish oil diet (FD) during the late gestation and lactation periods. During the gestation period, the SD was composed of 3% of soybean oil, while the FD was composed of 0.5% of soybean oil and 2.5% of fish oil; for the lactation diet, the SD was composed of 3.5% of soybean oil, while the FD was composed of 0.7% of soybean oil and 2.8% of fish oil.
As a result, sow and piglet performance did not differ between the SD and FD groups. The proportion of EPA in placenta increased in the FD group, whereas the proportion of DPA decreased. The fatty acid desaturases gene 1 (FADS1) mRNA expression in placenta decreased in the FD group. Moreover, the proportion of DHA in the red blood cells of piglets reduced from birth to day 16 in both groups, while the proportion of DHA in the livers of piglets continuously increased during the same time period in both groups.
All in all, these results indicate that fish oil supplementation during late gestation and lactation alters the n-3 long-chain polyunsaturated fatty acids composition in the red blood cells and livers of piglets. The decrease of the 22:5n-3 (DPA) and the increase of the 20:5n-3 (EPA) in placenta might be related to the regulation of n-3 long-chain PUFAs metabolism at the 22:5n-3 (DPA) formation step.
Luo W, Xu X, Luo Z, Yao J, Zhang J, Xu W, Xu J. Effect of fish oil supplementation in sow diet during late gestation and lactation period on litter characteristics, milk composition and fatty acid profile of sows and their offspring. Italian Journal of Animal Science. 2020; 19(1): 88-17. https://doi.org/10.1080/1828051X.2019.1685917