The objective of this study was to evaluate the effect of 30 g/kg DM from the tannins of oak leave and fruit (OL, OF), pistachio hull and leave (PH, PL) on in vitro ruminal degradation, gas production parameters and nutritive value of sunflower meal (SM) in ruminants. In vitro gas production, organic matter digestibility (OMD), metabolizable energy (ME) and fermentative parameters of samples were measured. Kinetics of gas production was fitted to an exponential model. The results showed that tannin of oak leave and pistachio hull did not influence the fermentable fraction (b) and gas production rate constant (c), but tannin of oak fruit and pistachio leave reduced these parameters (P<0.05), and the lowest (b) and (c) obtained for SM treated by 30 g/kg oak fruit tannin. The OMD and ME values of sunflower meal were decreased by tannin of oak fruit and pistachio leave (P<0.05). The lowest OMD and ME was for sunflower meal treated with oak fruit tannin, however, tannin of oak leave and pistachio hull did not influence these parameters. It means that using of some plant tannins with protein meals caused to decrease of OMD and ME of meal (P>0.05). The ammonia-N (NH₃-N) concentrations of culture fluid decreased (P<0.05) when SM was treated with all tannins sources used in this experiment. Concentration of NH₃-N and short chain fatty acid (SCFA) was lowest for SM treated by oak fruit tannin. The results showed that in vitro degradation; fermentation and nutritive value of sunflower meal are decreased by 30 g/kg DM tannin of oak fruit and pistachio leave. Therefore, tannin of oak leave and pistachio hull was proper than the other tannin sources to improving ruminal degradation and nutritive value of sunflower meal.

Key words: Nutritive value, Oak, Pistachio, Sunflower meal, Tannin