| The Rustic was used in simple contrast designs to study the effect of different nutrient diets supplemented yeast culture on rumen fermentation and fiber digestibility. Eight jars were divided two groups, one is supplemented without yeast cultures(CT),The other is added yeast cultures(YC).The experiment included 5 feedings periods of 7 days each according different diets. And each period comprised 5-day adaptation and 2-day data collection. The basal diets designs consisted of corn grain, soybean meal and straw to formulate low, middle and high nutrient level diets with three forge: concentrate ratio of 30:70,50:50 and70:30(air-dry basis),The added YC were expressed HD-YC, MD-YC,LD-YC and without YC were expressed HD-CT,MD-CT,LD-CT. The other basal diets designs consisted of corn grain, soybean meal and alfalfa formulate middle and high nutrient level diets with three forge: concentrate ratio of 30:70,50:50 (air-dry basis). The added YC were expressed HM-YC,MM-YC and without YC were expressed HM-CT,MM-CT. The test is aimed to study the effect of different nutrient diets supplemented the same yeast culture on ruminal pH, NHs-N, VFA (including acetate, propionate, butyrate, total VFA and the ratio of acetate/propionate),activities of four main relative fibrolytic enzymes(xylanase, CMCase, salicinase and filnase) and degradability of DM, OM, NDF and ADF of straw. The results indicated that:1. On the value of pH in rumenThere was no significant effect on pH at the every time point in the periods. But average pH were declined dramatically in middle and low level diets with straw than that of the control groups.2. On the concentration of ammonia-N in rumenThere was no significant effect on the concentration of ammonia-N in most tests(P>0.05).In diet straw ,The concentration of HD-YC was lower than that of HD-CT by 9%, The concentration of MD-YC was lower than that of MD-CT by 8%, But the LD-YC was higher than LD-CT by 23%;In diet alfalfa, HD-YC was higher dramatically than HD-CT by 12%, HM-YC was lower less dramatically than that of HM-CT by5%(P>0.05).3. On the concentration of VFA in rumenIn diet straw, the concentration of acetate, propionate, butyrate and total VFA ,The ratio of acetate to propionate in HD-YC,MD-YC,LD-YC were higher than those in control .the concentration of acetate was increased by 17%, 8%, 32%respectively. The propionate was increased by 5%, 0.2%,31% respectively. The butyrate was increased dramatically by 38%, 64%, 80% respectively. The total VFA was increased by 20%, 13%, 39% respectively. The ratio of acetate to propionate was increased by 17%, 3%, 1% respectively.In diet alfalfa, the concentration of acetate, propionate, butyrate and total VFA, The ratio of acetate to propionate in MM-YC, HM-YC compared with MM-CT, HM-CT, The concentration of acetate was increased than control. But propionate, butyrate, the ratio of acetate to propionate were decreased than control, and the butyrate, the ratio of acetate to propionate were decreased dramatically by 32%, 13% in MM-YC (P<0.05) . In HM-YC, they are all increased and only butyrate and total VFA were increased dramatically by 42%, 16% respectively (P<0.05).4. On the dynamic degraded parameters of DM, OM, NDF and ADF of straw in rumenThere was no significant effect on the dynamic degraded of DM, OM, ADF and NDF in all tests(.P>0.05). It is have little significant to research them.5. On the activities of relative fibrolytic enzymes in rumenIn diet straw, compared with control, in HD-YC, the xylanase salicinase and filnase activities were higher dramatically than HD-CT (P<0.01) . In MD-YC, they are all increased less dramatically than MD-CT. In LD-YC, only CMCase activities was higher dramatically than LD-CT.In diet alfalfa, compared with control, CMCase, salicinase and filnase activities were higher dramatically than MM-CT (P<0.01) ,In HM-YC, CMCase, salicinase and filnase activities were increased dramatically than HM-CT. xylanase activities was less dramatically increased. |
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