关键词: 饲草, 体外发酵, 反刍动物, CH₄, 温室效应

Abstract: To research the effect of different forages on the methane production from ruminants,the fermentation index of forages commonly used in the milk cow industry were tested after 72 h fermentation in vitro using an automated gas production recording system and a Gas Chromatography.Results indicated that the methane yields of tested forages were 56.85~74.63 mL·g^-1 DM loss after 72 h fermentation.The methane yield of corn(Zea mays L.) stalk was the highest one and alfalfa(Medicago sativa L.) hayⅠproduced the lowest yield of methane.In vitro fermentation from high to low is: corn silage,alfalfa hayⅠ,alfalfa hayⅡ,Chinensis hay(Leymus chinensis T.),alfalfa stem,corn stalk.The dynamics of gas yields produced by all tested forages followed an exponential function and had similar tendency to each other.The cumulative gas production increased rapidly in 0~24 h,the growth rate gradually slowed in 24~36 h,then became flat after 36 h.The methane yields of tested forages had significantly positive correlation to the content of its neutral detergent fiber(NDF),acid detergent fiber(ADF),and had negative correlation to the content of crude protein(CP).By stepwise regression analysis,the regression model is established between conventional nutrient content and methane production: P_CH4=60.02-0.91×CP+0.44×ADF(R²=0.96).Experimental results show that high-quality forage with high levels of in vitro fermentation and low methane productions will improve feed efficiency and reduce greenhouse effect,and poor-quality forages have the contrary.

Key words: Forages, In vitro fermentation, Ruminant, Methane, Greenhouse effect