Effects Of Dietary Physical Effective Fiber To Rumen Degradable Starch Ratios And Fumaric Acids On Rumen Fermentation, Microbial Communities And Methane Emission In Dairy Goats

As greenhouse effect becoming more serious, people paid increasing attention onenvironmental pollution. Methane is an important greenhouse gas represents an energy loss aswell as climate change. Fumaric acids (FA) can enhance the production of propionate bycapturing hydrogen. As H2is utilized to reduce fumaric acid, there is a decline in H2availablefor methanogenesis. Dietary CBI is a new indicator for measuring rumen health and animalproduction reflecting the source and processing way of feed. Low dietary CBI can producehigh proportion of propionate which is similar with the adding of fumaric acid. Therefore,dietary CBI and FA may have an interactive impact on the methane emission. This researchwas conducted to investigate the effects of dietary physical effective fiber to rumendegradable starch ratios (CBI) and fumaric acids on rumen fermentation, microbialcommunities, in situ degradation and methane emission in dairy goats. Four ruminallycannulated goats were used in a4×4Latin square design with a2×2factorial arrangement oftreatments and the main factors were set to be the dietary CBI (1.47or1.59) and FAsupplementation (0g/d or24g/d). Experiment contained four periods with24d each. Resultswere as follows:1. Adding FA significantly decreased CH4emissions/d and CH4emissions/kg DM(P<0.05). Although different dietary CBI had no effect and there were no CBI×FA interaction(P>0.05) on methane production, adding FA at higher CBI (CBI1.59) decreased more than thatof lower CBI (CBI1.47) in methane emissions/d and methane emissions/kg DMI. Adding FA inCBI1.59diet decreased31.72%of methane emissions/d but it only reduced17.91%in CBI1.47diet and the same trend was for methane emissions/kg DM.2. Supplementation of FA significantly increased the molar proportion of propionate,rumen pH and decreased the concentration of acetate, butyrate, acetate:propionate (P<0.05).Adding FA tended to increase the molar proportion of propionate (P=0.115). Increasingdietary CBI significantly decreased the concentrations and molar proportion of propionate,but increased the molar proportion of acetate and acetate:propionate (P<0.001). Total VFA, the concentration of actate and butyrate, rumen pH were not affected (P>0.05) by dietary CBI.There were interaction between dietary CBI and FA in the molar proportion of butyrate andacetate: propionate.3. Adding FA significantly reduced the amount of methanogen and B.fibrisolvens wereless abundant in the CBI1.59diet (P<0.05). No differencewas found among the amounts ofprotozoa, total Fungi, F.succinogenes, R.flavefaciens, parvula, S. ruminantium and the in situdegradation in both different dietary CBI and adding FA (P>0.05).The present study demonstrated that FA reduced methane emission by altering VFAfermentation types and decreasing the abundance of methanogen without negative effect on insitu degradation of feed. Different dietary CBI could change the rumen fermentation pattern.The FA may take greater effect in lower dietary CBI.