Effect of increasing GnRH dose during Double- Ovsynch on fertility of lactating dairy cows

Abstract

The rate of ovulation to the first GnRH treatment of Ovsynch-type protocols is key to achieve excellent fertility. In cows syn­chronized with the Double-Ovsynch protocol (DO), only around half of the cows ovulate to the third GnRH injection (first GnRH of the Breeding-Ovsynch portion of Double-Ovsynch). Increas­ing the dose of GnRH at this time has been proven to improve ovulatory response, reaching up to 67% of ovulation rate. Our objective was to determine whether increasing the dose of the third GnRH of DO could improve the reproductive outcomes at first service.