Effect Of Different Dietary Forage Quality And Adding Yeast Culture On Main Cellulolytic Bacteria And Fiber Digestion In The Rumen Of Sheep

A study on the dynamic changes of the on populations of three species of cellulolytic bacteria in the rumen of sheep fed dietary with different quality of forage using oligonucleotide probes to rRNA was carried out. The mechanism of the rumen microorganism how to degrade the fiber , through exploring the relationship among rumen microflora,cellulose and degradation of dietary fiber was elaborated. Under adding or not adding yeast culture condition, nine Inner Mongolian wether sheep with ruminal cannula, healthy , weighting 45Kg, were randomly divided into three groups fed three diets with different dietary forage quality on the same dietary ratio of forage to concentrat(eR/C)of 8:2, higher forage grading group (H group had GI value of 2.89MJ),middle one (M group had GI value of 1.73 MJ),low one(L group had GI value 0.65 MJ) according to Grading Index(GI) of forage .This experiment included two stages, and experiment animals were added yeast culture in the second stage. The results of this study were as follows:(1)The total bacteria counting and the populations of B.succinogenes in the rumen were affected significantly by different dietary forage quality. The total bacteria counting increased gradually and the population of B.succinogenes had an ascendant tendency when GI increased. The difference of the total cellulolytic bacteria counting among three groups were not significant (P>0.05), the total cellulolytic bacteria counting increased gradually when GI increased. The populations of R.flavefaciens increased significantly(p<0.05) ,and the total population of rumen bacteria and cellulolytic bacteria counting in the rumen tended to increase after yeast culture supplemented.(2)The mean value of relative populations of R.flavefaciens,R.albus and B.succinogenes in the rumen bacteria were 1.18%,2.44% and 10.07%, respectively, and the total cellulolytic bacterial counting was 13.68%.(3)The xylanase activity in every group increased gradually and H group was higher than L group when GI increased(P<0.05). The activity of FPA and pectinase were not affected significantly by different dietary forage quality(P>0.05), the activity of xylanase,FPA and pectinase were higher before feeding, and all values reached the peak value at 8h-12h after feeding. The activity of xylanase and pectinase tended to increase after yeast culture supplemented. (4)The ruminal effective degradability of dry matter and ADF were not influenced by different dietary forage quality(P>0.05), but NDF ruminal effective degradability was affected significantly,and H group was higher than L group(P<0.05). The ruminal effective degradability of DM and NDF tended to increase after feeding yeast culture to sheep.