Effect of feeding high protein dried distillers grains in beef finishing diets on carcass characterIstics, beef quality, and sensory attributes.

Abstract

Angus steers (n=48) were individually fed one of three dietary treatments in the feedlot finishing phase that included a conventional corn based diet (CON); a treatment containing 35% dried distillers grains with solubles replacing dry rolled corn (DDGS); and a treatment containing 35% high protein dried distillers grains replacing dry rolled corn (HPDDG). Including HPDDG in beef cattle finishing diets tended to reduce overall daily feed intake (P=0.08); however, average daily gain and final body weight were not affected (P=0.49 and P=0.54, respectively). There were no differences among treatments for dressing percentage (P=0.22), hot carcass weight (P=0.54), 12th rib back fat (P=0.18), and percent kidney pelvic and heart fat (P=0.35). Longissimus muscle was similar (P=0.57) among treatment and averaged 78.1 cm2 for across treatments. Average USDA Yield Grades were similar (P=0.54) for CON, DDGS, and HPDDG (2.56, 2.75, and 2.69, respectively). Marbling scores (where 500=small00, 600=modest00) were similar (P=0.26) across treatments. Fabrication loss was similar across treatments for the inside round, strip loin, and shoulder clod (P=0.20, 0.36, and 0.20, respectively). Drip and purge loss percentages were similar across treatments (P=0.49 and 0.16, respectively). Shear force values did not differ among treatments (P=0.25) and averaged 2.54, 2.37, and 2.88 kg, respectively. Consumer sensory scores for overall liking (P=0.10), texture liking (P=0.47), toughness (P=0.17), and off flavor (P=0.20) did not differ among treatments; however, there was a trend for higher flavor liking ratings for CON steaks compared to HPDDG (P=0.06). High protein dried distillers grains steaks were rated the highest for juiciness (8.49). For cooked sausage, CON rated the highest for overall liking and flavor liking (P=0.01 and P=0.04, respectively). The CON and HPDDG sausages were rated higher than DDGS for texture liking and toughness (P=0.01 and P < 0.001, respectively). For strip steak objective shelf life, treatment did not affect L* or b* values (P=0.87 and 0.43, respectively), however treatment did affect a* values (P=0.0001). Redness values were higher for CON as compared to DDGS and HPDDG. Treatment affected subjective scores for lean color, surface discoloration and overall appearance (P=0.0001) of strip steaks. Objective shelf life analysis of ground beef, summer sausage, and bologna indicated that treatment did not affect mean L*, a*, or b* values (P=0.15, 0.16, and 0.23 respectively). CON ground beef had a more desirable subjective lean color (P=0.001) and overall appearance (P=0.001) than DDGS and HPDDG. Treatment had no effect on bologna subjective scores for lean color and surface discoloration (P=0.07 and 0.10, respectively).Treatment did affect mean overall appearance (P=0.03), with higher values for CON as compared to DDGS and HPDDG. For summer sausage, there was no effect of treatment on subjective scores for lean color (P=0.35) surface discoloration (P=0.38) and overall appearance (P=0.31). Treatment had no effect on saturated fatty acid and monounsaturated fatty acid percentage (P=0.44 and 0.86 respectively), however; treatment did affect polyunsaturated fatty acid (P=0.0001), with CON having lower values than DDGS and HPDDG. There was no difference between treatments on d 0 (P=0.50) for lipid oxidation in ground beef, however, on d 7 HPDDG had increased values compared to DDGS and CON (P=0.001) as indicated by TBARS. Results indicate that beef cattle finished on diets containing high protein dried distillers grains may replace up to 35% of corn grain in feedlot diets and not affect carcass characteristics, moisture loss, and shear force of fresh beef products. However, inclusion of HPDDG in the diet at 35% may increase lipid oxidation resulting in a decrease in shelf life and unfavorable changes in sensory characteristics of fresh steaks. Keywords: Distillers Grains, High Protein, Beef Quality