Observations on the reproductive effects of once or twice weekly injections for 6 weeks of the GnRH agonist deslorelin in the cow

Abstract

This study investigated the reproductive effects in Holstein-Friesian cows of once or twice weekly intramuscular injection for 6 weeks of 100 μg of the GnRH agonist deslorelin at intervals. Oestrus was synchronized in non-lactating Holstein-Friesian cows before they were allocated randomly to receive either 100 μg deslorelin once weekly (D1; N = 10) or twice weekly (D2; N = 8) or acted as untreated controls (CON; N = 8). The first injection was given on day 6 post-oestrus and the last injection on day 48 post-oestrus. Blood samples were collected twice weekly from each cow until day 76 after the synchronized oestrus to profile plasma P4. A single injection of prostaglandin was administered t..