Serum Progesterone and Conception Rates in Acyclic Embryo Recipient Mares Using a Bovine Progesterone-Releasing Intravaginal Device.

The objective of this study was to quantify serum progesterone levels, uterine features, and pregnancy rates in acyclic, embryo recipient mares using a bovine progesterone-releasing intravaginal device in a commercial embryo transfer (ET) program. The study included 73 recipient mares of unknown breed, aged 3-10 years, weighing 350-500 kg, and kept under an intensive management system on Tifton 85 (Cynodon spp.) pastures with water and mineral salt ad libitum.