Nguyen, Vu Quang, Le, Van Hung, Nguyen, Don Viet, Malau-Aduli, Bunmi S., Nichols, Peter D., and Malau-Aduli, Aduli E.O. (2019) Enhancement of dairy sheep cheese eating quality with increased n-3 long-chain polyunsaturated fatty acids. Journal of Dairy Science, 102 (1). pp. 211-222.

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Abstract

This study investigated the effect of different plant oil-infused and rumen-protected wheat-based pellets containing eicosapentaenoic acid (EPA, 20:5n3) and docosahexaenoic acid (DHA, 22:6n3) on n-3 long-chain (≥C20) polyunsaturated fatty acids (n-3 LC-PUFA) content, fatty acid recovery and sensory attributes of ripened cheese from dairy sheep. During a ten-week supplementary feeding trial, sixty dairy ewes balanced by liveweight, milk yield, parity,and sire breed were randomly divided into six groups: (1) Control: supplemented with on-farm existing commercial wheat-based pellets without oil inclusion; supplemented with wheat-based pellets infused with 50 ml/kg DM of oils from (2) canola (CO); (3) rice bran (RBO); (4) flaxseed (FSO); (5) safflower (SFO) and (6) rumen protected EPA+DHA (RPO). Milk samples from each treatment were collected separately by sire breed during the experimental period for cheese processing at the end of the experiment. Twelve batches of cheese (2 batches per treatment) were processed and ripened for 120 days. Three cheese samples were collected and analysed for each cheese making session (total of 36 cheese samples) at day 120 of ripening. Processed cheese of RPO had the most efficiency at elevating total n-3 LC-PUFA (ΣEPA+DHA+DPA; docosapentaenoic acid, 22:5n3) content (P<0.001) compared to the control (0.49 vs 0.28%). FSO elicited the greatest enhancement of α-linolenic acid (ALA, 18:3n3), while SFO was the most effective diet in enhancing the level of linoleic acid (LA, 18:2n6) in cheese (P<0.001) (1.29 vs 0.71%; 4.8 vs 3.3%; respectively). Parallel recoveries of n-3 and n-6 LC-PUFA were observed across all treatments except for ALA (P=0.0090), and EPA (P=0.0098). Cheese eating sensory traits were also highly affected by oil supplementation with the highest score of 7.5 in cheese from the RBO and FSO treatments (P<0.001). These results provide new insights into the biological mechanisms and processes that determine dairy ewe milk productivity by underpinning the vital biological role of n-3 LC-PUFA in not only enhancing the healthy composition of cheese from ewes, but also translating into consumer acceptability.

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