Improved fertility following a gonadotropin-releasing hormone treatment on day 2 of an estradiol and progesterone-based timed-artificial insemination protocol in lactating dairy cows

Summary: This study evaluated 3 strategies to initiate an estradiol/progesterone-based timed-artificial insemination protocol: (1) estradiol benzoate (EB) only on d 0, (2) EB plus GnRH on d 0, and (3) EB on d 0 and GnRH on d 2. Compared with the negative control group (EB only on d 0), adding GnRH on d 2 increased overall fertility, and particularly benefited the following groups of cows: multiparous cows, cows with higher milk production, and cows receiving the first postpartum service.