Effects Of Exogenous Fibrolytic Enzymes On Main Sites And Their Modes In Digestive Tract Of Ruminants

Three health Chinese Holstein lactating cows with permanent ruminal cannulas were selected as experimental animals. The experiment consisted of three experimental periods, each comprised 20 days. During each experimental period, the diet of cows was supplemented with 0(control), 1kg of fibrolytic enzyme preparationⅠor 1kg of fibrolytic enzyme preparationⅡper tonne of dry matter(DM). The studies were as follows:①Effect of exogenous fibrolytic enzymes on digestion of nutrients in the rumen,such as effect of rumen fermentation, fiber degradation and microbial N flow to duodenum.②Effect of exogenous fibrolytic enzymes on rumen microbial population of dairy cows, such as protozoa,bacteria,fungi quantities; establishments of a relative quantification of real-timePCR for Use in fibrolytic bacteria and studies on the effect of exogenous fibrolytic enzymes on rumen fibrolytic bacteria.③Effect of exogenous fibrolytic enzymes on digestion and matebolization in dairy cows.In another experiment, 6 two years old Inner Mongolian semi-fine wool sheep(body weight, 27～30kg), fitted with permanent cannulas in the rumen and at the proximal duodenum and terminal ileum were divided into 2 groups of 3 in one factor experimental design. The diet of sheep was supplemented with 0(control), 1kg of fibrolytic enzyme preparationⅠper tonne of dry matter(DM). The studies were as follows:①Establish an assay method for Use in measurement of fibrolytic enzymes activity in digestive tract of ruminants.②Effect of exogenous fibrolytic enzymes on cellulase and xylanase activity in rumen and small intestine.The result showed as follows:①The exogenous fibrolytic enzymes were beneficiol to rumen fermentation; The digestion of DM,NDF,ADF in rumen and the microbial N flow to duodenum were increased significantly after supplementing exogenous fibrolytic enzymes(P<0.05～0.01).②Exogenous fibrolytic enzymes increased the cellulase and xylanase activity in rumen and small intestine of sheep(P<0.05～0.01).③Exogenous fibrolytic enzymes increased the total number of rumen ophryoscolex,bacteria,fungi(P<0.05～0.01)and quantities of fibrolytic bacteria.④Exogenous fibrolytic enzymes increased the apparent digestion of DM,NDF,ADF and CP(P<0.05～0.01). At the same time the dietary digestible N and N retention were increased significantly after supplementing exogenous fibrolytic enzymes(P<0.05～0.01). But the exogenous fibrolytic enzymes did not significantly affect the balance of energy in dairy cows(P> 0.05).The results of this study demonstrate that the main sites of Action of exogenous fibrolytic enzymes is in rumen. The main modes of action of exogenous fibrolytic enzymes in digestive tract of ruminants are that improve the rumen environments and fermentation, it increased microbial population and cellulase and xylanase activity in rumen and small intestine that further increased digestion of nutrients and the microbial N flow to duodenum. With the increased of fibrolytic enzymes activity in small intestine ,the digestion and matebolization of whole digestive tract are enhanced.