Reproductive performance of lactating dairy cows and heifers resynchronized for a second insemination with an intravaginal progesterone-releasing device for 7 or 8 d with estradiol benzoate injected at the time of device insertion and 24 h after removal

Abstract

One aim of this study was to compare the reproductive performance of cows and heifers when resynchronizing returns to estrus for a second insemination by treating with an intravaginal progesterone-releasing device (IVD) for 7 or 8 d when estradiol benzoate (EB) was administered at the start of treatment and again 24 h after device removal. An additional aim was to document the pattern of onset and characteristics of estrus with each resynchrony treatment. Lactating cows in three herds were synchronized for a first estrus and AI by treatment with an IVD for 8 d, starting on Day 0, cloprostenol (0.5 mg im) at device removal and EB at device insertion (2.0 mg im) and 24 h after removal (1.0 mg ..