Methane Production Of Different Forages In Vitro Fermentation

Greenhouse gases emissions from ruminants is an important factor of global warming. Previous studies showed that the diet composition of ruminants and chemical composition have a significant impact on rumen methane fermentation. In order to research the effect of different forages on the methane production from ruminant, and select some plant which inhibit methane emissions from ruminant livestock. This study collected cow rumen fluid, using an automated gas production recording system for in vitro fermentation based on virtual instrumentation and a Gas Chromatography to study methane production, in vitro dry matter digestibility, total gas production, gas production dynamics and total volatile fatty acids concentration of fermentation liquor of six kind of commonly used forages in milk cow industry and eleven kind of main herbages of xilinguole typical grassland area after the 72 h fermentation in vitro. The main results as follows:The methane production of six kinds commonly used forages that corn silage, corn stalk, domestic alfalfa hay, domestic alfalfa stem, imported alfalfa hay, Leymus Chinensis hay in milk cow industry after the 72 h fermentation in vitro is lies between 56.85～74.63 mL/g DM loss, the highest of the methane production is corn stalk and the lowest is domestic alfalfa hay. The methane production of the tested forages play a larger contribution to the cumulative gas production, and the methane produced mainly in the slow fermentation.The tested forages'degree of in vitro fermentation in turn is as followings: corn silage, domestic alfalfa hay, imported alfalfa hay, Leymus Chinensis hay, domestic alfalfa stem, corn stalk. The gas production dynamics of forages showed a change of exponential function, the tendency is similar. In 0~24 h, the cumulative gas production increased rapidly, in 24~36 h, the growth rate gradually slowed, and becomes flat after 36 h. The methane production of forages is significantly positive correlation to the content of its neutral detergent fiber (NDF), acid detergent fiber (ADF), very significantly negative correlation to the content of its crude protein (CP). As it, forages methane production prediction model was built: 4PC H( ml / g DM ) + 60.02+ 0.91C P+ 0.44 ADF (R ?0.980). Experimental results show that high-quality forage with high levels of in vitro fermentation, and low methane production, thereby improving feed efficiency and reduce the greenhouse effect, while the poor quality forage opposite.The methane production of eleven kind of main herbages of xilinguole typical grassland area after the 72 h fermentation in vitro is lies between 40.32～60.56 mL/g DM loss, the highest of the methane production is cleistogenes squarrosa, and the lowest is oakleaf goosefoot. In general, the methane production of typical grassland wild herbages is lower than commonly used forages in milk cow industry, it's clearly that make ruminant livestock ingest wild herbages in natural status can reduce greenhouse gas emissions significantly. The plants of lower CH4 production in vitro fermentation include crowded onion, silverweed cinquefoil and Leymus Chinensis, they may be the natural methane inhibitor or material that can extract methane inhibitor that this study looking for. The methane production of 11 main herbages in the grassland is positive correlation to the content of its NDF and ADF, negative correlation to the in vitro dry matter digestibility and content of its CP, but the correlation is no significant. It is the same as the correlation above between methane production of 6 dairy cow used herbages and nutrient index, in vitro dry matter digestibility of common forage. Therefore, the linear relationship by studing commonly used forage of dairy has certain representativeness. After the Leymus chinensis steppe and the Stipa krylovii steppe in which Leymus chinensis and Stipa krylovii are the dominant species respectively evolved to moderately degraded grassland in which Artemisia frigida and Cleistogenes squarrosa are the dominant species, the dominant species of the later produce less methane in providing 1kg CP to dairy cow, has the potential to reduce greenhouse gas emissions. But with the severity of degradation, after further evolution to the severe degree degraded grasslands, The potential methane production of dominant species in providing 1kg CP to dairy cow significantly increases 20.98% and 28.95% than the dominant species of the Leymus chinensis steppe and the Stipa krylovii steppe which are non-degradated, increases 61.43% and 31.44% separately than the dominant species of Artemisia frigida which is moderatly degradated. Grazing ruminant will tend to choose the forage of low CH4 yield by studing selective grazing of grazing sheep in Inner Mongolia and seasonal changes of diet, it is presumed that the methane emissions grazing ruminant in the whole grazing season shows a single peak curve, the peak is in the summer.