The effects of several levels of grape pomace extract on in vitro intestinal digestibility of dairy cow

The experiment was carried out to study the effect of different doses of grape pomace extract (GE) on ruminal degradation and post-ruminal digestion of basal diet in dairy cow using a modified two-step in vitro method. The VFA، ammonia production and protozoa population determined. Six levels of extract were used: GE0: basal diet، GE1، GE2، GE3، GE4، GE5 contains 12، 24، 36، 48 and 60 µl extract/50 ml inoculum respectively. Ruminal degradation of DM (rdDM) in GE3، GE4، GE5 was lower comparing to GE0، but ruminal degradation of CP (rdCP) by adding GE was decreased. Digestibility of DM (tdDM) and CP (rdCP) in GE4 and GE5 diets were lower with comparing to GE0. Addition of GE increased the proportion of rumen escape CP (pdBCP) and degradability of bypass CP in HCl/pepsin (dBCP). The population of proteolytic bacteria only declined in GE4 and GE5 diets comparing to GE0. Total VFA، acetate concentrations and acetate propionate ratio were lower in GE3، GE4، GE5 diets compared to GE0. NH3-Nproduction، total number of protozoa، subfamily of Entodiniinae and genus of Dasytricha were decreased as the level of GE increased. With the By addition of GE، genus of Isotricha and subfamilies of Diplodiniinae and Ophrioscolecinae at the 12 and 24 h of incubation was lower than the control. In conclusion، GE supplementation has reduced protozoa population، NH3-N and protein degradation in the rumen and increased degradability of bypass CP