Effects of Dietary Glycerin on Carcass Characteristics, Fatty Acid Profile, and Volatile Compounds in Longissimus Dorsi Muscle of Korean Steers

Dietary glycerol may improve beef quality by affecting glycogen content and marbling. This study was performed to evaluate the effect of a glycerin-increased diet on growth performance, carcass characteristics, chemical composition, sensory traits, fatty acid profile, and volatile compounds in longissimus dorsi muscle (LM) of beef cattle. Twenty Korean steers (BW = 647±10.49 kg and 27 mo of age) were divided into a control diet group (n = 10) and a glycerin-increased diet group (n = 10). Diets were formulated to meet or exceed NRC (2000) requirements. Control diet, which was conventionally designed for finishing period of Korean cattle, was used in this study. For the glycerin-increased diet, the portion of molasses and distiller’s dried grains with solubles (DDGS) in the control diet were replaced with a 3% crude glycerin with iso-energy nutrient levels (TDN = 87%, DM basis) as control diet. All steers were allowed daily to receive a concentrate with the amount of 1.5% of BW and 1.0 kg of rice straw. Feeding trial was performed for 5 months. Water was allowed ad libitum. All data were analyzed by ANOVA using GLM of SAS. Concentrate intake was 14% higher (P < 0.01) in glycerin group compared to control group, while rice straw intake was not different between two groups. Average daily gain and feed efficiency (gain/feed ratio) were not different between two groups (P > 0.05). Animals were slaughtered after the feeding trial, and LM samples were collected from hot carcasses within 2h after slaughter and frozen for chemical analyses. The carcasses were kept at 4℃ for 24h and graded with Korean standard grading methods. LM samples were also collected from cold carcasses at 24h for analysis of sensory traits. Carcass weight, LM muscle area, backfat thickness, marbling score, yield grade, and quality grade were not different between two groups (P > 0.05). Contents of protein, fat, collagen, reducing sugar, and glycogen in the LM were not different between two groups (P > 0.05). Sensory traits (appearance, flavor, taste, tenderness, juiciness, and overall acceptance) and percentages of fatty acids and volatile compounds in the LM were not different between two groups (P > 0.05). In conclusion, the glycerin-increased diet improved feed intake, although it did not affect daily gain and feed efficiency. The glycerin-increased diet did not affect beef quality, including marbling, glycogen contents, sensory traits, and percentages of fatty acids and volatile compounds in the LM.