The object of this study was to determine the influence of supplementation of concentrate containing high levels of cassava chip on rumen ecology, microbial protein and digestibility of nutrients. Four, rumen fistulated crossbred beef steers with initial body weight of 400±10 kg were randomly assigned according to a 4×4 Latin square design. The dietary treatments were concentrate cassava chip based offering at 0, 1, 2 and 3% BW with urea-treated rice straw fed ad libitum. It was found that ruminal pH was significantly decreased with increase of concentrate. Volatile fatty acids (VFA) concentration in the rumen was significantly different among treatments. In addition, a molar proportion of propionate was higher in supplemented groups at 2 and 3% BW (p<0.05), leading to significantly decreased acetate:propionate ratio. Furthermore, microbial N supply was significantly improved and was highest at 2% BW supplementation. The efficiency of rumen microbial-N synthesis based on organic matter (OM) truly digested in the rumen was highest in level of concentrate supplementation at 2% BW (80% of cassava chip in diets). Moreover, bacterial populations such as amylolytic bacteria was linearly increased, while cellulolytic bacteria was linearly decreased (p<0.01) when cattle received concentrate supplementation in all levels. The total protozoal counts were significantly increased, while fungal zoospores were dramatically decreased in cattle receiving increased levels of concentrate. In conclusion, cassava chip can be use as energy source at 80% in concentrate and supplementation of concentrate at 2% BW with urea-treated rice straw as roughage could improve rumen fermentation efficiency in beef cattle.

Abstract.A total mixed ration (TMR) containing a blend of feedstuffs naturally contaminated with harmful mycotoxins was fed for 84 days to 24 primiparous and multiparous Holstein-Friesian · local dairy cows in a randomised complete block design. The dietary treatments consisted of a contaminated TMR diet plus various levels of the mycotoxin deactivator product (MDP) (0, 15, 30 or 45 g/head.day). Deoxynivalenol (DON), fumonisin B 1 (FB 1 ), zearalenone (ZON) and ochratoxin A (OTA) were found in the TMR at levels up to 720, 701, 541 and 501 mg/kg, whereas aflatoxin B 1 (AfB 1 ) and T-2 toxin (T-2) were found in the TMR at levels of 38 and 270 mg/kg, respectively. Rumen microbial ecology, ruminal volatile fatty acid (VFA) concentrations, ruminal microorganism populations, feed intake, total tract digestibility, milk yield, milk composition and serum immunoglobulin (Ig) concentrations were measured. The results revealed that the ruminal pH, ruminal ammonia nitrogen (NH 3 -N) concentration, total ruminal VFA concentrations and ruminal bacterial counts were significantly (P < 0.05) higher in supplemented than in non-supplemented cows. Ruminal protozoal counts were significantly (P < 0.05) lower in supplemented than in non-supplemented cows. DM intake, and digestibility of crude protein (CP) and neutral detergent fibre (NDF) were significantly (P < 0.05) higher in supplemented than in non-supplemented cows. Serum IgA concentrations were significantly (P < 0.05) higher in supplemented than in non-supplemented cows. Milk yield and milk protein were significantly (P < 0.05) higher in supplemented than in nonsupplemented cows. On the basis of this experiment, it can be concluded that milk production and feed intake can be increased with the addition of MDP to cow diet in the presence of mycotoxins. These increases were accompanied by decreases in the negative effects of mycotoxins on rumen and immune function.

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