Characteristics of Wet Distillers Grains on In vitro Ruminal Fermentation and Its Effects on Performance and Carcass Characteristics of Finishing Hanwoo Steers

Two experiments were conducted to determine the nutrient composition, in vitro ruminal ammonia concentrations and pH of wet distillers grains (WDG, produced from tapioca 70% and rice 30%) and to evaluate dietary effects of fermented total mixed ration (TMR) using WDG on the performance, blood metabolites and carcass characteristics of Hanwoo steers from mid fattening to slaughter. In Exp. I, average dry matter (DM), crude protein, ether extract, crude fiber, ash, neutral detergent fiber, acid detergent fiber, and nitrogen free extract of seven WDG samples from an ethanol plant with different sampling dates were 19.9%, 24.8%, 3.8%, 21.8%, 8.87%, 60.3%, 34.5%, and 40.7% (DM basis), respectively. For in vitro ammonia concentrations and pH, each sample was assigned to 7 incubation times (0, 4, 8, 12, 24, 48, and 72 h). Linear increase was observed between 12 and 48 h for ammonia concentrations, but final ammonia concentrations (72 h) were not significantly different among WDG samples and fermentation patterns of WDG samples showed similar tendency. In vitro pH varied among treatments from 0 to 24 h, but were not different statistically after 48 h. In Exp. II, 45 Hanwoo steers of 23 months (641±123 kg) from mid fattening period to slaughter (248 days) were randomly divided into three groups of 15 pens each (five repetitions/each treatment) and assigned to one of three dietary treatments; i) Control (TMR), ii) WDG 15 (TMR containing 15% of WDG, as fed basis) and iii) WDG 28 (TMR containing 28% of WDG, as fed basis). The body weight (BW), ADG, and feed conversion ratio (FCR) of control and WDG 15 and 28 during 248 days were 760.8, 740.1, and 765.5 kg, and 0.50, 0.50, and 0.52 kg/d, and 18.6, 17.6, and 17.1, respectively. The dry matter intake (DMI) (kg/d) of control (9.11) was higher (p<0.05) than WDG treatments (WDG 15%, 8.57; 28%, 8.70). Nevertheless, DMI did not affect BW, ADG, and FCR of Hanwoo finishing steers. Blood metabolites were in normal ranges and were not different among treatments except the albumin concentration. In carcass characteristics, WDG 15 (30%) showed higher frequency of A-carcass yield grade than WDG 28 (15%) and control (7%), and WDG 28 (61%) showed higher frequency of 1(++) and 1(+)-carcass quality grade than WDG 15 (40%) and control (60%). In conclusion, using WDG up to 28% in TMR did not show any negative effect on the performance and blood metabolites, and improved carcass quality of Hanwoo steers. Therefore, WDG can be a useful feed ingredient for Hanwoo steers in mid-fattening period to slaughter.