A new method for induction and synchronization of oestrus and fertile ovulations in mice by using exogenous hormones.

Four consecutive experiments were conducted to design and establish the effectiveness of different protocols for induction and synchronization of oestrus and ovulation in mice. Results showed that the highest synchronization degree and the highest fertility rates were obtained using two intraperitoneal doses of 0.5 microg of cloprostenol, three days apart, plus a single subcutaneous dose of 3 microg of progesterone coincidentally with the first injection of cloprostenol. Of the main advantages of the new method, we have to highlight the short time elapsed for appearance, and the high degree of synchronization of oestrus and ovulations (almost 100% of the animals responding to the treatment in 48 h; 78.4% with fertile mates at 24 h), plus the high fertility rate obtained after a programmed mating (100%). Overall, these yields are superior to those obtained by classical methods based on the use of male pheromones; hence the proposed protocol arises as an adequate alternative for reproductive management in mice.