Effects of Feeding Brassica Mixture Cover Crops During Backgrounding on Carcass Traits and Fresh Meat Quality

The effect of a rumen-protected long chain fatty acid (LCFA) supplement on live performance, carcass characteristics, and tenderness was evaluated in this study. Angus steer calves (n = 99, 12 pens, n = 8-9/pen) were fed a low energy diet for 77 days prior to finishing. Steers were transitioned from the low energy forage-based diet to a high concentrate diet containing high moisture ear corn, corn silage, dry rolled corn, soybean meal, and a liquid supplement containing monensin across 21 days. Megalac-R (RPFA), a LCFA supplement, was fed to 6 pens at 2% of the diet dry matter. Control pens (CON; n = 6) received an additional 2% of diet dry matter (DM) as dry rolled corn and soybean meal. The final finishing diet net energy for gain (NEg) was 1.20 and 1.19 mega calories.kg-1 of DM for RPFA and CON treatments respectively. Steers were weighed every 28 days and used to calculate growth performance data. After a 147-day finishing phase, steers were transported to a commercial abattoir for slaughter. Long chain fatty acid supplementation during the finishing phase did not increase marbling scores of the steers in this study but did increase final live weight, and hot carcass weight. These results suggest RPFA supplementation has the potential to increase tissue development within the body. However, it is likely that animal age during supplementation and duration of supplementation impact the effect RPFAs have on carcass characteristics. Introduction Marbling, a primary factor used for quality grading in the U.S. beef industry has a strong relationship to beef carcass value (USDA, 2018). Consumers are willing to pay a premium for beef with increased marbling (Platter et al., 2005). Marbling positively influences beef flavor and juiciness, two major attributes that contribute to palatability (Mcbee and Wiles, 1967; Behrends et al. 2005; Brewer et al., 2007; Felderhoff et al., 2007). The supplementation of rumen-protected LCFA’s (Mangrum et al., 2016) and rumen-protected polyunsaturated fatty acids (Cooke et al., 2011) has increased marbling in carcasses from early weaned steers and feeder cattle when compared with non-supplemented controls. The objective of this study was to determine the effect of feeding a rumen-protected LCFA fed during finishing on live performance, carcass traits, and tenderness. We hypothesized that supplementation of a rumen-protected LCFA during the finishing phase would increase marbling scores. Experimental Procedures Angus steers (n = 99; initial body weight 796 ± 1.34 lbs) from a single source were received at the South Dakota State University Ruminant Nutrition Center and fed for 77 days to achieve a weight gain of 2.65 lbs per day. On day 78, steers were adapted to a grain-based diet or a grainbased diet that contained high moisture ear corn, corn silage, dry rolled corn, soybean meal, and a liquid supplement containing monensin across 21 days. Megalac-R (RPFA) was fed to 6 pens at 2% of the diet dry matter (Table 1). Control pens (CON; n = 6) received an additional 2% of diet dry matter as dry rolled corn and soybean meal (Table 1). Due to feed availability, diet