In this study, an in vitro rumen gas production technique was utilized to evaluate the effect of foeniculum vulgar (fennel) methanolic extract (0 and 1 ml/30ml buffered rumen fluid) on degradability of sunflower meal. The feed sample(200mg sunflower meal plus extract were incubated with rumen liquor taken from three fistulated talesh cow at 2,4,6,8,12,24,48,72 and 96h. result show that gas production was reduced on addition extract of fennel in 2 hour after incubation and in other time of incubation cause increase gas production in contrast to the control group. Result showed that extract of fennel increased water soluble fraction (a) the slow degradable fraction (b), the potential degradability (a+b) and decreased degradation rate of the slow fraction(c). This study suggested that fennel extract have the potential to affect fermentation efficiency.
