This study investigated the effects of dexamethasone and insulin on energy and protein metabolism, reproduction and milk production in dairy cows. Two hundred Holstein cows were enrolled in a randomized controlled clinical trial. The cows were randomly assigned to receive 1 of 4 treatments at 3 or 10 days in milk: control group, 10-mL i.m. injection of sterile water, group insulin, s.c. injection of 100 units of insulin, group dexamethasone, i.m. injection of 20 mg of dexamethasone, group insulin plus dexamethasone, i.m. injection of 20 mg of dexamethasone and 100 units of insulin. Serum samples obtained at the time of enrollment, time of treatment and at 2, 4, 7 and 14 days after intervention. The sera were analyzed for β-hydroxybutyrate (BHBA), nonesterified fatty acids (NEFA), glucose, cholesterol, albumin, urea, and aspartate amino transferase (AST). To assess reproductive performance, the following outcomes were measured: interval from calving to first insemination, calving to conception interval, first service pregnancy risk (%), pregnancy rate at 120 days in milk , and cumulative pregnancy risk (%) till 9 month. All analyses were performed using SAS software. Data were analyzed using a repeated measures mixed model that accounted for the effects of parity, body condition score, dystocia, retained placenta, metritis and the random effect of cow. Kaplan- Meier survival function estimates were used to calculate crude associations of treatment with median time to first breeding and pregnancy, and to generate graphs of cumulative pregnancy risk over time. There was no significant interaction of group of treatment and time of intervention (day 3 or 10 post-partum) on serum components. Cows that received insulin or dexamethasone alone or in combination, had significantly (P<0.05) lower BHBA 2 days after treatment compared with control cows, whereas concentrations of NEFA, were unaffected suggesting that glucocorticoids lipolytic effects do not appear to be important in healthy cows. AST activities significantly reduced in cows that received dexamethasone with or without insulin at 2 and 4 days after treatment. Albumin and urea concentrations 2 days after treatment were higher for cows that received dexamethasone only or dexamethasone plus insulin compared with control and Ins received cows. There were no treatment effects on test-day milk production, milk fat and protein percentages. Dexamethasone treated cows had significantly lower days to pregnancy than controls. In addition, dexamethasone treated cows had a significantly greater pregnancy rate at 120 days in milk than other treatment groups and controls. The odds of the development of pregnancy at 120 days were 2 times greater in cows that received dexamethasone in comparison to controls (P=0.02). In conclusion administration of glucocorticoids in early lactation resulted in short-term improvement of metabolism in postpartum dairy cows in biochemical terms and a single dose of dexamethasone injection in early lactation, might improve reproductive performance.

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