PSXV-25 Effects of multiple grass-fed and grain-fed beef systems on meat fatty acid composition

Retail sales of labeled fresh grass-fed beef in the U.S. have grown from $17 million in 2012 to $272 million in 2016. The objective of present study was to investigate the effect of four typical grass-fed and conventional beef systems raised in the western United States on beef fatty-acid composition. Treatments included: 1) steers stocked on pasture then finished in a feedyard (CON), 2) steers grass-fed for 20 months (GF20), 3) steers grass-fed for 20 months with a 45-day grain finish (GR45), and 4) steers grass-fed for 25 months (GF25). Fatty acids were analyzed with GC using a 100 m CPSil 88 capillary column. All statistical analyses were performed using a GLM procedure in R. Saturated fatty acid (SFA) concentrations were significantly different across treatments (P < 0.05) with GR45 having the lowest SFA of 43% and GF25 having the highest SFA at 46%. Cis-monounsaturated fatty acid (c-MUFA) particularly oleic acid, which is known as a heart healthy fatty acids, were highest for CON at 44% and lowest for GF20 at 37% (P < 0.05). Conjugated linoleic acids (CLA) were significantly lower for the grain-fed treatments (0.54 CON and 0.63 GR45; P < 0.05) compared to grass-fed treatments (0.93 GF20 and 0.86 GF25; P < 0.05). The grass-fed treatments were higher in n-3 PUFA (3.67 GF20 and 2.29 GF25) than CON (0.79; P < 0.05), however feeding grain for a short period of time did not decrease n-3 PUFA concentrations to the CON level (GF45 2.51; P < 0.05). In conclusion, our findings show that beef from grain-fed beef management systems is higher in c-MUFA, while grass-fed is significantly higher in bioactive fatty acids including CLA and branched chain fatty acids. Additional studies are needed to determine if fatty acid profiles between grass-fed and grain-fed beef would result in different health outcomes for the consumers.