The present study was conducted to evaluate the effects of dietary formulated feed additive on growth performance and carcass traits of Hanwoo steers. A formulated feed additive reported to reduce heat load in the rumen in our previous research was used (Cho et al., 2014). Total 32 herds of Hanwoo steers were assigned into two groups of control and treatment. Total mixed ration was provided as basal diet for cattle and 100 g of additive was supplemented on diet for treatment. Feeding trial was performed during 120 days before slaughter. For growth performance, 3 periods (0~90 days; 90~120 days; 0~120 days) were allotted and average daily gain, feed requirement and final body weight were determined. Loin meat between 12th and 13th rib was used for meat quality analysis after slaughtering. Only 1st period showed significantly improved growth performance of treatment (P<0.05) and there were no significant difference in other periods. At 3rd periods (overall), a trend of increased average daily gain was found at treatment (P=0.075). Carcass performance and quality did not show significant differences between treatment and control (P>0.05). In meat quality, treatment showed significant increment in all measured meat colors (P<0.05) and significantly less sharing force compared to the control (P<0.05). Although no significant difference in growth performance and carcass yield were found, remarkably improved economic status was detected in treatment group. In conclusion, it could be suggested that application of a formulated feed additive specialized in reduction of heat load in the rumen was able to increase economical balance through enhancing heat stress condition of ruminant and growth.

본 연구는 반추위 메탄저감용 약용식물 첨가제 개발을 위해 유산균을 이용하여 발효한 두충 및 감초 추출물의 항균활성, 항산화활성 및 in vitro 반추위 발효시험을 실시하였다. 발효 약용식물 추출물 제조를 위해 접종된 종균의 성장효율을 조사하기 위해 실시한 생균수 측정 결과 L. curvatus NJ40, L. brevis NJ42 및 L. plantarum NJ45가 두충과 감초 모두에서 유의적으로 높은 균주 성장을 나타냈다(p<0.05). 항균활성측정 결과는 두충과 감초 추출물에서 공통적으로 L. curvatus NJ40 및 L. plantarum NJ45 로 발효한 추출물이 일부 병원균에 대한 항균효과를 나타내는 것으로 조사되었다. In vitro 반추위 발효시험에서 두충 및 감초 발효 추출물을 적용한 결과, 감초 추출물에서 메탄 저감효과가 나타났다. 특히 반추위내 미생물 발효 특성을 대표할 수 있는 휘발성지방산 생성효율을 향상 시키면서, 전반적 반추위 발효에 부정적 영향이 없는 것으로 나타났다.