Abstract

Fatty acid profiles of backfat (BF), intermuscular fat (IMF), kidney pelvic heart (KPH) fat and tail fat (TF) depots from 15-mo old Angus cross steers finished on grass (GS; n = 18) were compared to those finished on a grain diet (GN ; n = 14) to examine how diet and fat depot impacts fatty acid composition. GS steers grazed an average of 10 months (mo) on ryegrass and white clover irrigated pasture and GN finished steers were a corn based finishing diet for 4 mo. Overall, fat from GS steers contained higher percentages of C6:0 (P = 0.008), C12:0 (P = 0.003), C14:0 (P = 0.001), C16:0 (P = 0.002), C18:3 (P = 0.008), C20:0 (P < 0.001), C18:1 trans9 (P = 0.004), C18:2 cis9 cis12 (P < 0.001) and C18:2 trans9 trans12 (P < 0.001) than GN steers. Fat from GN steers contained higher percentages of C18:0 (P < 0.001). For both GS and GN steers, C18:0 content was higher in the KPH and IMF compared to BF and TF (P = 0.015) depots and C18:1 cis9 content was lower in KPH compared to BF and TF depots (P < 0.001). Therefore, fatty acid composition differs due to diet and differs across depots. Manipulating diets and source of fat (depot) could be used as strategies to modify the fatty acid composition of meat products to increase health benefits to consumers.

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