| The exogenous enzymes in ruminants were used in the 1960s, but the responses were variable. Until to 1990s, researchers reexamined in detail the role of exogenous enzymes in ruminant production and get good results, but compared with norumiants, the quantity of exogenous enzymes products used in ruminants were smaller.4 cellulases and 4 xylanases made in china were selected to determine the effects of pH and dosage on enzyme activities in order to get optimum pH condition of enzymes action and the best enzymes products, then a series studies were conducted to determine the effects of exogenous fibrolytic enzymes, enzymes+formic acid on the fermentation quality of forage silages and to investigate the effects of exogenous fibrolytic enzymes treated forage on rumen fermentation and ruminal bacterial community in continuous culture in vitro. The results were as follows.1 Effects of the different pH value and adding dosages on enzyme activities and reducing sugar releaseUnder the condition of pH5.0,5.5,6.0,6.5 and 7.0, A xylanase activity was the higher compared with other enzymes. A enzyme activity was very stable at pH ranging from 5.0, to 6.0 and retained more 65% at pH 7.0. The optimum range of pH were 5.0 to 5.5 for B xylanase, with pH up to 6.0, the B xylanase activity was decreased rapidly. The optimum pH for C xylanase activity was 6.0, but the enzymes activity was lowest among enzymes. D xylanase activity was very stable at testing pH condition. CMCase activities were very higher at pH 5.0 and 5.5, but with pH increasing, the activity was decreased for a, b, c and d enzyme. CMCase activities for b and d enzymes were higher than a and c enzymes. The optimum pH of Avicelase activities for a, b, c and d enzymes was 6.0,5.0,6.0 and 5.5 respectively. Avicelase activities of b and d enzymes were higher than a and c enzymes activities.With increasing enzymes level, the reducing sugar release was high significant for A, B xylanase and a, b cellulase under pH6.0 and the same substrate level, but the release quantity of reducing xylose was greatest at the 0.008 mg level of A xylanase. The release quantity of reducing sugars was not enhanced further in addition of mixture of cellulase +xylanase in the substrate of xylan or CMC-Na.2 Effects of fibrolytic enzymes on the fermentation quality of elephant grass (Pennisetum purpureum Schumach.) silagesThis study was conducted to research the effects of the fibroltyic enzymes on the fermentation quality of elephant grass silages. Chopped elephant grass were ensiled in laboratory mini-silos either untreated (control) or treated with cellulase(250 or 500 mg-kg-1), cellulase(250 mg-kg-1) plus xylanase(250 mg-kg’), xylanase(250 or 500 mg-kg-1), respectively. The results showed that the enzymes treatments reduced rapidly the pH value(P<0.01), and enhanced significantly content of lactic acid(P<0.01) and water soluble carbohydrate(P<0.01) of silages compare with control. The content of ammonia nitrogen in the enzymes treated silages, expect for cellulase plus xylanase treated, was lower than the untreated silage (P<0.05) and the content of acetic acid, except high level of cellulase treatment, were no difference (P>0.05) in the silages at the end of ensiling. The exogenous fibrolytic enzymes improved the fermentation quality of elephant grass silage during ensiling.3 Effects of formic acid, fibrolytic enzymes on the fermentation quality of Italian ryegrass (Lolium multiflorum Lam.) and white clover(Trifolium repens L.) mixture silageThis experiment was conducted to examine the effects of formic acid, fibrolytic enzymes on the fermentation quality of Italian ryegrass and white clover mixture silages. The mixture material of 80% Italian ryegrass+20% white clover was ensiling in the plastic bags either untreated (control) or treated with formic acid (0.3%), cellulase(1.0 mg-kg-1), formic acid+cellulase(0.3%+1.0 mg·kg-1), xylanase(1.0 mg·kg-1), formic acid+xylanase (0.3%+1.0 mg·kg-1), cellulase+xylanase(1.0 mg-kg-1, respectively) and formic acid+ cellulase+xylanase (0.3%+1.0 mg·kg-1+1.0 mg·kg-1). The results showed that formic acid treatment or formic acid plus enzyme treatments decreased the pH value (P<0.05), LA content and NH3-N content (P<0.05), increased WSC contents (P<0.05) of silages compared with untreated silage; the enzyme treatments enhanced significantly WSC contents, LA contents and Ac contents (P<0.05) of silages and decreased the pH value, NH3-N contents, NDF and ADF content (P<0.05) of silages, compared with control during ensiling. The formic acid and exogenous fibrolytic enzymes can improve mixture silages quality of ryegrass and white clover and the results treated with enzymes were better than formic acid or formic acid plus enzymes treatment.4 Effects of fibrolytic enzymes on enzymes activities and fermentation of Chinese wildrye or maize silages by mixed ruminal microorganisms in vtiroTwo of in vitro studies were conducted to determine the effects of mixture treatment of cellulase and xylanase on enzymes activities and fermentation of Chinese wildrye or maize silages by mixed ruminal microorganisms. Three levels of fibrolytic enzyme supplements (0,10.0 and 50.0 mg, respectively) and two treatment times (0 and 24 h before incubation) were tested. The enzyme treatment increased xylanase and CMCase activities 0 and 8 h postincubation and Avicelase activity 0 postincubation for Chinese wildrye. The level of enzyme affected enzyme activities. Then, the exogenous enzyme addition did not affect enzymes activities in incubation fluid at 24 and 48 h of incubation. The AA content at 24 and 48 h of incubation, the total VFA contents at 8,24 and 48 h of the incubation were increased (P<0.05) by the enzyme treatment. Enzyme treatment increased (P<0.05) the cumulative gas production and tended to increase the ratio of acetate to propionate (P=0.138) at the end of incubation. Enzyme treatment had no effects valerate and isovalerate concentrate (P>0.05). In the experiment of enzymes treated maize silages, the enzymes treatment increased xlyanase activity at 0 h, CMCase activity at 0 and 8 h and Avicelase activity at 0,8 and 24 h of the incubation. Date from this study suggest that addition of fibrolytic enzymes to Chinese wildrye or maize silage by mixed ruminal microorganisms can enhance xylanase and cellulase activities in the initial 8 h of the incubation and had no effect the enzyme activity at 24 and 48 h of the incubation and improved rumainal fermentation characteristic in vitro. 5 Effects of the fibrolytic enzymes on ruminal bacterial community in vitro incubationThe effect of the fibrolytic enzymes on ruminal bacterial community in vitro incubation was analyzed by PCR-DGGE technology. The analysis of DGGE profiles revealed that the fibrolytic enzyme treatment did not affect the composition of the rumen bacterial community. The sequence similarity analyses of the all clone sequences in 16S rDNA library resealed that 6 clones showed similarities with database sequences over 97%, the rest similarities in a range of 84%-96%.7 clone sequences were similar to Selenomonas ruminantium, Butyrivibrio fibrisolvens, Butyrivibrio hungatei, Eubacterium uniforme, Succinivibrio dextrinosolvens, Roseburia faecis, Bovine ruminisbacterium. The rests were uncultured rumen bacterium. All of clone sequences get a Genebank number (accession No: HQ645848-HQ645865). |
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