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Estrogen Pre-Treatment of Corticoid Induced Parturition in Cattle^{1, 2,}

Montana State University, Bozeman 59715

Abstract

Estrogen pre-treatment of corticoid induced parturition was studied in 31 2-year-old heifers and 24 cows to determine if estrogen, given in such a way as to possibly mimic blood estrogen levels seen at normal parturition, would alleviate the retained placental condition encountered in corticoid induced parturition. The cows were randomly assigned to either a control group, a dexamethasone treated group (DEX) or a dexamethasone plus estrogen group (DEX+E) and all cows in the DEX or DEX+E groups received 20 mg of dexamethasone 17 days prior to their expected calving dates. Estrone, estradiol-17 and estradiol-17ß were administered at varying levels from 6 days prior to dexamethasone treatment to either day prior or 1 day past dexamethasone treatment.

Treatment with dexamethasone alone or with estrogen resulted in shortened gestation length, increased retained placenta and decreased birth weight (P<0.01). The addition of estrogen to the dexamethasone treatment did not affect the rate of induction success, the time from dexamethasone injection to parturition or the incidence of retained placenta, but it did increase calving difficulty over both the DEX and control groups (P<0.01). Calf vigor was not affected by any treatment. None of the three estrogens affected the time from dexamethasone injection to parturition when compared to the DEX group, but estradiol-17 shortened this time when compared to the estrone and estradiol-17ß treatments (P<.05). No differences were detected in gestation length, retained placenta, calving difficulty, calf vigor, birth weight, or induction success between the estrogen treatments.

¹ Journal series No. 400.

² The authors wish to acknowledge the assistance of G. E. Moss, C. H. Clark and E. P. Smith in handling the livestock and in collecting and statistically analyzing the data.