Supplementation of rumen protected glucose (RPG) may be a useful dietary strategy to improve energy balance in transition dairy cows. The present study was performed to investigate whether supplementation with RPG could improve metabolic status, milk production and reduce infection during the transition period in cows. Fifty five healthy Holstein dairy cows (4–5 years old; 515 ± 42 kg body weight; 32.1 kg milk production per day) with the second lactation were enrolled in the study. Cows were randomly assigned into two groups: group (1) control group which fed on control diet, group (2) RPG group which
fed on control diet supplemented with RPG at rate of 250 g/cow/day. Supplementation was applied from 20 day before parturition to 60 days postpartum. Blood was sampled on 21 postpartum to examine some serum biochemical parameters [glucose (GLU), non-esterified fatty acid (NEFA) - β-hydroxybutyric acid (β-HBA) and insulin (INS]. Results showed that
serum glucose level was insignificantly different between RPG supplemented and control cows. On the contrary, a rapid decrease was observed in concentration of NEFA and β-HBA and activity of aspartate aminotransferase (AST) in response to RPG supplementation. Meanwhile, dietary RPG supplementation increased plasma concentration of insulin (INS) relative to control cows