The Effect Of Different ADF Levels On Rumen Fermentation And Population Of Cellulolytic Microbes In The Rumen Of Nanjiang Goat

The present experiment was conducted to study the effect of different Fiber levels on rumen fermentation and Populationof Cellulolytic Microbes in the rumen of Nanjiang goat. First, the effect of dietary fiber levels on rumen fermentation was investigated, and then studied the degradation of dietary in Nanjiang goats by using nylon bag method. At last, the effect of different dietary fiber levels on rumen bacterial community of Nanjiang goat was measured.In Trial 1, the effect of different dietary fiber levels on rumen fermentation of Nanjiang goat was studied. Four ruminally fistulated Nanjiang goats of similar body weight of (22±1) kg were used in this experiment to provide rumen fluid. The dietary fiber (ADF) levels were 14.86%,19.88%,24.52%,28.91% and 34.12% for group ADF15, group ADF20, group ADF25, group ADF30 and group ADF35 respectively. Gas production was measured at 0,2,4,6,8,10,12,24,48 and 72 h respectively, and determined the pH, volatile fatty acids, microbial protein content and cellulase activity of the rumen fluid which cultured with this five kinds diets for 6h,12h,24h and 48h. The experimental results showed: The different fiber levels dietary can effects the rumen fermentation and the cellulase activity Significantly. The pH was increased as dietary ADF increased. When ADF concentration in diet was 24.52%, gas production and the concentration of total VFAs and MCP were the highest, and the concentration of NH3-N and the ratio of acetic acid/propionic acid was the lowest. In general, the optimal level of ADF for ruminal fermentation was 24.52%. The xylanase activity compared with the rest of the three cellulase was the highest. When the dietary ADF content was 26.16%, the xylanase activity was the highest; when the dietary ADF level is 25.05%, the activity of carboxymethyl cellulose was the highest; and when the dietary ADF level was 25.43%, the microcrystalline cellulose activity was the highest.In Trial 2, Four goats fisted cannulas were used to investigate the effects of different dietary fiber levels (ADF levels were 14.86%,19.88%,24.52%,28.91% and 34.12%) on the feed degradation in rumen of Nanjiang goat by using nylon bag method. And measured the degradation rates of DM, OM, CP, NDF and ADF of these dietaries in rumen of Nanjiang goats. Results from the experiment showed that the ADF levels of dietary effects the degradation rates of DM, OM, CP, NDF and ADF of these dietaries significantly. The rusults of regression analysis showed:when the ADF concentration of the dietary was 25.61%, the DM degradation rate was highst; when the ADF concentration of the dietary was 25.21%, the OM degradation rate was highst; and when the ADF concentration of the dietary was 25.49%, the NDF degradation rate was highst.In Trial 3, the effect of different dietary fiber (ADF levels were 14.86%,19.88%, 24.52%,28.91% and 34.12%) on the rumen bacterial community and the number of F. Succinogenes, R. albus and R. flavefaciens of Nanjiang goat was measured by using DGGE and RT-PCR. The results showed that the different levels of dietary fiber have influence on the rumen bacterial community. And the bacterial species and number of the group which ADF concentration was 24.52%was the highst. The different fiber levels dietary can effects the number of fibrolytic bacteria in rumen, too. Conditions in high-concentrate, with the increase of the dietary fiber level, the number of F. Succinogenes,R. albus and R. flavefaciens in rumen were increased. But if the level of the dietary fiber was too high will reduced the number of F. Succinogenes, R. albus and R. flavefaciens in rumen. The rusults of regression analysis showed:when the ADF concentration of the dietary was 25%, the number of F. Succinogenes was highst; when the ADF concentration of the dietary was 25.14%, the number of R. albus was highst; and when the ADF concentration of the dietary was 24.35%, the number of R. flavefaciens was highst.It could be concluded that:the ADF level of dietary can significantly affect the rumen fermentation characteristics,feed rumen degradability and the number of rumen cellulolytic bacteria. when the ADF concentration of the dietary was24.35%-26.16%,the rumen environment of Nanjiang goat was stable, and will be beneficial to the growth of fibrolytic bacteria in rumen, the cellulase activity and feed degradation in rumen were the highst.