Four ruminally cannulated Hanwoo steers (BW 600 ± 48.4 kg) fed whole crop rice silage (WRS) as forage were used to investigate the effects of its dietary on rumen fermentation and blood metabolites at different harvesting time such as milk, dough, yellow ripe and mature stages of WRS, respectively. Mean ruminal pH sampled at 0, 1, 2, 4, 6 and 8 h after the morning feeding was not significantly (p>0.05) different between the WRS by the harvesting time. In diurnal pattern in ruminal pH, the

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... pH for the mature stage treatment (Mature) appeared at 6 h after the feeding while it appeared at 2-4 h for the other treatments. This may indicate that retention time in the rumen of Hanwoo fed WRS harvested at the Mature increased. Although feeding WRS harvested at different stages did not significantly (p>0.05) affect ruminal ammonia N concentration, the ammonia N for WRS harvested at the milk stage (Milk) tended (p=0.11) to decrease compared with that for the yellow stage treatment (Yellow). In the blood metabolites analysis, BUN concentration for Yellow numerically decreased compared with that for Milk. This, taking lower concentration of ruminal ammonia N for Milk than the other treatments into account, clearly indicates that the BUN concentrations may not increase in proportion to ruminal ammonia N concentration according to ammonia N concentration entering into the lower gastric tracts. Lower (p=0.03) concentration of blood albumin for the dough stage treatment than that for Mature may indicate high protein synthesis in Hanwoo fed WRS at the dough stage, but further studies in terms of mechanism of nutrients distribution should be required. Present results indicate that different harvesting time did not affect rumen fermentation and blood metabolites in Hanwoo. Thus, based on the results of the present and the previous studies, utilizing WRS harvested at yellow stage could be recommendable for Hanwoo steers. (Key words : Rumen fermentation, Whole crop rice silage, Hanwoo, Blood metabolites) 서 론 . 총체벼를 가축사료로 사용하고자 하는 움직 임은 아시아국가 중 우리나라 및 일본과 같이 쌀 생산성은 지속적으로 향상되는데 비해 소비 량이 감소하는 나라에서 비교적 활발하게 진행 1 대구대학교 (Daegu University)