In experiment 1, we investigated the effects of partial replacement of barley grain with beet pulp (BP) on performance, ruminal fermentation and plasma concentration of metabolites in transition dairy cows. Results showed that replacing of barley grain with BP by 25%, increased DMI during the transition period. Postpartum ruminal functions indicated that substituting barley grain by BP increased ruminal pH, acetate: propionate ratio and molar proportion of butyrate, while ruminal molar concentrations of acetate and propionate tended to increase and decrease, respectively. Prepartum blood parameters were similar between treatments. Substitution of barley grain by BP up to 25% of diet resulted in higher milk yield. In experiment 2, we considered the effect of rumen-protected conjugated linoleic acid (RP-CLA) on diet of 25% BP containing basis, on performance and plasma concentration of metabolites in transition dairy cows. Results showed that supplementation of RP-CLA increased blood glucose concentration in prepartum. RP-CLA increased DMI and milk yield but decreased milk fat percentage in postpartum. Body weight and back fat thickness were similar among treatment in pre and postpartum period. Keywords Beet pulp, barley grain, conjugated linoleic acid, transition period
