Abstract
Three fistulated nonlactating Holstein cows were used to examine the change in ruminal characteristics when fed diets of 100% corn silage, 50% corn silage + 50% wet brewers' grain(WBG) and 100% WBG, and also twenty Holstein heifers averaging 156 $\PM$ 3.2kg BW were randomly assingned to determine the adequate feeding level of concentrate with the following treatments ; Only WBG, concentrate to 0.5, 1.0 and 1.5% of BW under feeding WBG ad libitum. Tne main results were as follows : I. Ruminal pH was minimized 3 hrs after feeding and then gradually increased. The mean ruminal pH was highest in feeding only WBG (6.72) and lowest in only corn silage(6.0) 2. Ruminal $NH_3$-N concentration was maximized 1 hr after feeding and then gradually decreased regardless of diets, n7e average ruminal $NH_3$-N content was highest in diet of 100% WBG(12.9 rngldl) and lowest in 100% corn silage(5.9 mg/dl) 3. Acetic acid percent among VFA was highest when WBG replaced 50% corn silage and acetic to propionic acid ratio was higher in order of feeding only corn silage, 50% corn silage + 50% WBG and only WBG. 4. Ruminal bacteria and protozoa number in diet of 50% corn silage + 50% WBG were 8.14 $\times$ > $10^5$ and 1.45 $\times$ $10^5$, respectively, which were most of all treatments. 5. Daily gain and feed efficiency of Holstein heifer in feeding concentrate to 0.5% of BW and forage hay to about 20% of total DM intake when fed free WBG were better
