Abstract: The effects of adding different levels of linseed oil(LSO) in Leymus chinensis meal on gas production,rumen fermentation,and fatty acids in fermentation fluid were investigated using in vitro procedure.Treatments were control, Leymus chinensis meal containing 5% or 10% of LSO and cultured 48 h in vitro.The total gas production, methane and hydrogen production were measured at 12,24 and 48 h.After 48 h,rumen fermentation parameters and fatty acids in fermented liquid were measured.The results showed that LSO significantly reduced the gas and methane production,improved rumen fermentation and increased the hydrogen production;LSO significantly increased the total volatile fatty acid(TVFA),the proportion of propionate and butyrate,and significantly reduced the pH and ammonia nitrogen concentration;At the same time,LSO increased the proportion of conjugated linoleic acid and other unsaturated fatty acid which were beneficial to human health.In conclusion,addition of LSO in the forage can suppress methane production,improve rumen fermentation and increase the concentration of polyunsaturated fatty acids(PUFA).

Key words: methane, rumen fermentation, fatty acid, in vitro