Doses of prostaglandin analogue “cloprostenol” by intravulvo-submucosal (IVSM) injections effective for the induction of oestrus in goats

Abstract

In order to ensure that all goats responded equally to varying dosages of cloprostenol (Clo.) without considering the stage of the oestrous cycle, 25 goats were injected (treatment A) between days 11 and 14 of the oestrous cycle with 125 μg Clo./goat intramuscularly (IM). At the time of the second injection, given 11 days later, five different treatments (treatment B), consisting of 125 μg Clo.IM, 125 μg Clo. IVSM, 62.5 μg Clo. IVSM, 31.25 μg Clo. IVSM and saline IM, were given to groups 1, 2, 3, 4 and 5, respectively. Oestrus was monitored by teaser bucks. Blood samples taken at the time of treatment B and daily for 6 days thereafter were assayed for progesterone to confirm that luteolysis had occurred as expected. All goats in groups 1, 2 and 3, and one out of five in group 4 exhibited oestrus within 68 h of treatment B. Serum progesterone levels exhibited values below 1 ng/ml within 24 h of treatment B in groups 1, 2 and 3 and decreased to nadir levels within 48 h of treatment B. Lack of luteolysis in goats of groups 4 and 5, as shown by progesterone concentrations, was the reason for failure of synchronization in these groups. It is concluded that a small dose of cloprostenol given by intravulvo-submucosa injection is effective in inducing oestrus in dioestrous cycling goats.