Effects of supplementation of flax meal and flax oil on mammary gene expression and activity of antioxidant enzymes in mammary tissue, plasma and erythrocytes of dairy cows

The effects of antioxidants from flax meal (FM) and abomasal infusion of flax oil (FO) on the activity of antioxidant enzymes (superoxide dismutase, catalase and glutathione peroxidase (GPX)) in blood and mammary tissue and the mRNA abundance of antioxidant and lipogenic-related genes in mammary tissue of dairy cows were determined. Eight ruminally fistulated lactating Holstein cows were assigned to a double 4×4 Latin square design with a 2×2 factorial arrangement of treatments: (1) control diet with no FM (CON); (2) diet containing 124 g/kg FM (FMD) in the dry matter (DM); (3) CON and 250 g FO/d infused in the abomasum; (4) FMD and 250 g FO/d infused in the abomasum. Catalase activity in erythrocytes tended to increase when cows were fed FMD. Abomasal infusion of FO had no effect on activity and gene expression of antioxidant enzymes and gene expression of lipogenic-genes in mammary tissue, except for an increase in GPX1 expression in the absence of FM. The results suggest that feeding 124 g/kg FM and infusing 250 g of FO/d in the abomasum of dairy cows does not induce significant changes in the activity of antioxidant enzymes in blood and mammary tissue, and expression of antioxidant and lipogenic-genes in mammary tissue. However, more studies are required to determine any beneficial effects of natural antioxidants such as FM on the oxidative status of cows supplemented with polyunsaturated fatty acids, which could lead to feeding strategies to prevent diseases affecting the health status of dairy cattle.