Abstract: Ten, one year old of native cattle with initial body weight of 150 ± 10 kg were randomly divided into two groups and received concentrate at 14% CP (T1) and Yeast Fermented Cassava Chip (YFCC) (T2). The cows were offered the treatment concentrate at 1% BW and ruzi grass was fed ad libitum. Means were compared using T-test. All animals were kept in individual pens and received free access to water. The results have revealed that replacement of YFCC on feed intake was non-significantly different, while Average Daily Gain (ADG) was higher (p<0.05) in native cattle fed YFCC (T2) treatments than received concentrate at 14% CP (T1) (259 and 205 g/d). In addition, the ruminal pH, ammonia-nitrogen and blood urea nitrogen concentration were significantly different (p<0.05). Supplementation of YFCC (T2) could improve population of bacteria and fungal zoospore, but decreased populations of Holotrich and Entodiniomorph protozoa in rumen (p<0.05). The results indicate that supplementation of Yeast Fermented Cassava Chip (YFCC) as a replacement concentrate at 14% CP could improve rumen fermentation efficiency in native cattle.