Supplementing Dairy Ewes Grazing Low Quality Pastures with Plant-Derived and Rumen-Protected Oils Containing Eicosapentaenoic Acid and Docosahexaenoic Acid Pellets Increases Body Condition Score and Milk, Fat, and Protein Yields

SIMPLE SUMMARY: This study evaluated the lactation performance and body condition scores of purebred Awassi and Awassi × East Friesian crossbred dairy ewes grazing low quality pastures and supplemented with diverse plant-derived oil enriched pellets under on-farm management conditions. The origin and treatment of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) to get the rumen protected EPA + DHA treatment was based on a modification of the microencapsulation of oil droplets in a protein-aldehyde matrix procedure. The results demonstrated that supplementation with rumen (EPA + DHA) and oil-infused pellets improved milk, fat, and protein yields by approximately 30%, 13%, and 31% respectively, and crossbred ewes produced more milk than purebreds. These results are very useful for dairy sheep producers in improving ewe lactation performance, milk quality, and body condition score under low quality pasture grazing conditions. ABSTRACT: The Australian dairy sheep industry is small and mostly based on a natural grass grazing system, which can limit productivity. The current study tested different plant oil-infused and rumen protected polyunsaturated fats and their interactions with sire breeds to improve lactation traits and body condition scores (BCS) of ewes grazing low quality pastures. It was hypothesised that supplementing lactating ewe’s diets with plant-derived polyunsaturated oils would improve milk production and composition without compromising BCS. Sixty ewes (n = 10/treatment) in mid-lactation, balanced by sire breed, parity, milk yield, body condition score, and liveweight, were supplemented with: (1) control: wheat-based pellets without oil inclusion; wheat-based pellets including; (2) canola oil (CO); (3) rice bran oil (RBO); (4) flaxseed oil (FSO); (5); safflower oil (SFO); and (6) rumen protected marine oil containing eicosapentaenoic acid and docosahexaenoic acid (RPO). Except for the control group, all supplementary diets included the same level of 50 mL/kg DM of oil and all diets were isocaloric and isonitrogenous. Experimental animals were grazed in the same paddock with ad libitum access to pasture, hay, and water during the 10-week study. RPO was the most effective diet that enhanced milk, fat, and protein yields by approximately 30%, 13%, and 31%, respectively (p < 0.0001). A significant increase in milk production was also observed with CO, RBO, and SFO treatments (p < 0.0001). Breed significantly influenced animal performance with higher milk yields recorded for crossbred Awassi × East Friesian (AW × EF) (578 g/day) vs. purebred Awassi (452 g/day) (p < 0.0001). This study provides empirical evidence for the use of rumen-protected and plant-derived oil-infused pellets as supplements under low quality pasture grazing conditions to improve the production performance of purebred Awassi and crossbred AW × EF ewes.