Comparison of the Ovsynch Protocol and Exogenous Progesterone with Insemination at an Induced Estrus as Therapeutic Strategies for Ovarian Cysts in Lactating Dairy Cows

Abstract

It has been suggested that an underlying mechanism in the development of bovine ovarian cysts involves a hypothalamic lesion which causes follicular estrogen to be ineffective in inducing a GnRH/LH surge at the time of estrus. This lesion involves the estrogen receptor alpha (ERa). Furthermore, it has been speculated that treatment with progesterone may induce the ERa in the mediobasal hypothalamus which will foster a GnRH/LH surge in response to follicular estrogen. Collectively, this information suggests that therapeutic strategies for bovine ovarian cysts could involve either the use of GnRH or exogenous progesterone. An intra vaginal progesterone insert (EAZI-BREED™ CIDR®) has been approved for use in lactating dairy cows. The use of a CIDR to synchronize estrus detection is relatively simple and less labor intensive than the OvSynch protocol. Therefore, it could be a more acceptable treatment for ovarian cysts in lactating dairy cows. However, there is no information available concerning the comparative efficacy of these two treatment strategies. The hypothesis of this study was that lactating dairy cows with ovarian cysts treated with exogenous progesterone, a luteolytic dose of PGF2a, and inseminated at an induced-estrus, will have a higher pregnancy rate compared to cows with ovarian cysts subjected to the OvSynch protocol. The purpose of this study was to compare the effectiveness of these two protocols.