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

摘要

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 50mLkg(-1) DM of either canola (CO), rice bran (RBO), flaxseed (FSO), or safflower (SFO) oils on enhancing the concentration of n-3 long-chain (C-20) 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 50mLkg(-1) DM of CO; 3) RBO; 4) FSO; 5) SFO; and 6) RPO at the rate of 1kgday(-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%) (P0.0001). FSO improves levels of EPA (0.11%) and DPA (0.15%), while CO increases DPA (0.13%) (P0.0001). FSO and RPO reached the source and good source of n-3 LC-PUFA (sigma EPA+DHA+DPA) contents of 35.1 and 61.7mg 250mL(-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.Practical Applications: The results promote the potential for production of premium quality and health-beneficial fresh milk through dietary supplementation of grazing dairy ewes with plant-derived oil and rumen-protected EPA+DHA. Interactions between supplemented diets and week of supplementation on the concentrations of LA (a), ALA (b), EPA (c), DHA (d), and DPA (e) in milk.