Supplementing Grazing Dairy Ewes with Plant‐Derived Oil and Rumen‐Protected EPA+DHA Pellets Enhances Health‐Beneficial n−3 Long‐Chain Polyunsaturated Fatty Acids in Sheep Milk

This study investigates the impact of supplementing dairy ewes in mid lactation with rumen‐protected (RPO) pellets containing eicosapentaenoic acid (EPA, 20:5n−3) and docosahexaenoic acid (DHA, 22:6n−3) or pellets infused with 50 mL kg−1 DM of either canola (CO), rice bran (RBO), flaxseed (FSO), or safflower (SFO) oils on enhancing the concentration of n−3 long‐chain (≥C20) polyunsaturated fatty acids (n−3 LC‐PUFA) in milk. It is hypothesized that including these oils in the diet of grazing dairy ewes will improve milk fatty acid (FA) composition by increasing levels of n−3 LC‐PUFA. Sixty grazing dairy ewes balanced by sire breed and parity are randomly allocated to one of 6 treatments: 1) Control: commercial pellets without oil inclusion; 2) pellets containing 50 mL kg−1 DM of CO; 3) RBO; 4) FSO; 5) SFO; and 6) RPO at the rate of 1 kg day−1 for each ewe for 8 weeks. Weekly bulked daily milk FA analysis shows RPO has the most efficiency at elevating n−3 LC‐PUFA content by twofold, threefold, and fivefold greater concentrations of EPA, DPA, and DHA, respectively, than the control (0.17 vs 0.08%, 0.23 vs 0.08%, 0.19 vs 0.04%) (P < 0.0001). FSO improves levels of EPA (0.11%) and DPA (0.15%), while CO increases DPA (0.13%) (P < 0.0001). FSO and RPO reached the “source” and good “source” of n−3 LC‐PUFA (ΣEPA + DHA + DPA) contents of 35.1 and 61.7 mg 250 mL−1, respectively. These findings recommend that rumen protected pellets containing EPA + DHA, flaxseed, and potentially canola oil supplements, can be used to improve the content of n−3 LC‐PUFA in dairy ewe milk.