Comparison of Three Feeding Regimens on Blood Fatty Acids Metabolites of Wujumqin Sheep in Inner Mongolia

SIMPLE SUMMARY: The traditional sheep feeding system in Inner Mongolia, based on pasture grazing, is gradually transforming into a semi-grazing plus supplementation or feedlot approach, as grassland ecological protection becomes increasingly important. The fatty acid composition of the animals’ tissues changes with transformation of the feeding system. However, the changes to blood fatty acid metabolites in sheep as a result of alterations to the feeding regimen are unknown. In this study, pasture feeding, pasture feeding plus corn supplementation, and barn feeding were carried out to explore the effects of feeding regimens on blood fatty acid composition and metabolic pathways of sheep using a metabolomic approach. The results revealed that compared to grazing, concentrate supplement feeding regimens, including either grazing plus supplements or feeding indoors, down-regulated blood n-3 PUFA biosynthesis and up-regulated blood inflammatory compound metabolism by n-6 PUFA. These data suggest that under different feeding regimens, an appropriate ratio of n-6/n-3 PUFA in ruminant diets will contribute to increasingly high-quality animal production and improved immunocompetence. ABSTRACT: Feeding regimens influence the fatty acid composition of animal-derived products. However, there is limited information on the effect of feeding regimens on the blood fatty acid composition and metabolic pathways of ruminant animals. In this study, 30 Wujumqin sheep were randomly assigned to three groups, PF (pasture feeding), PSF (pasture feeding plus corn supplementation) and BF (barn feeding), to examine the effects of feeding regimens on blood fatty acid composition and metabolic pathways through a metabolomic approach. The results showed that the BF sheep had increased serum n-6 polyunsaturated fatty acids levels, while the PF and PSF sheep had increased serum n-3 PUFA levels. Compared to the BF and PSF sheep that were fed ground corn, the PF sheep that only ate natural grass had up-regulated serum DHA levels. Meanwhile, blood metabolites from linoleic acid and arachidonic acid, including pro-inflammatory products (20-HETE, LTs, TX etc.) and anti-inflammatory products (LXB4, DHETs, HPETEs etc.) were elevated in the BF group. It was found that, compared to grazing, concentrate supplement feeding regimens, including either grazing plus supplements or feeding indoors, down-regulated blood n-3 PUFA biosynthesis and up-regulated the blood inflammatory compound metabolism by n-6 PUFA.