Repeated low doses of dexamethasone as a pretreatment for induction of parturition in Simmental cows

Abstract

The aim herein was to evaluate the effects of the induction of parturition using repeated low doses of dexamethasone in cattle. A total of 28 Simmental cows were used for the induction of parturition (n = 20) or served as controls (n = 8). Parturition was induced by a 1.6-mg intramuscular (IM) injection of dexamethasone twice daily for 6 days, beginning on day 270, and a 40-mg IM injection of dexamethasone on day 276. The calf birth weight, incidences of dystocia, daytime parturitions, and placental retention were compared. The calf birth weights in the treatment and the control groups were 34.95 ± 1.01 and 38.25 ± 1.36 kg, respectively (P = 0.081). Calving difficulty was experienced by 2 cows (10%) in the treatment group, while calving assistance was needed for 50% of the control cows. Most calvings (90%) in the treatment group were observed during the daytime while only 1 daytime calving was observed in the control group (12.5%). The placentas were retained in 20% and 12.5% of the treatment and the control cows, respectively. In the treatment group, 11 cows calved before the completion of the induction protocol and 9 cows calved after the last dexamethasone injection (9.29 ± 2.07 h). The late calving cows had higher (P < 0.05) estrone sulfate concentrations than the early calving cows. Serum cortisol concentrations were higher in the early calving cows when compared to the late calving cows during the induction protocol (P < 0.001). In conclusion, the induction of parturition using repeated low doses of dexamethasone improved calving management.