Comparative Data about Estrus Induction and Pregnancy Rate on Lacaune Ewes in Non-breeding Season after Melatonin Implants and Intravaginal Progestagen

Abstract

Backgroung: Seasonal anestrus in ewes reduces reproductive efficiency and hinders productivity. Exogenous hormones can be used to facilitate the induction and synchronization of estrus in the anestrus period. The aim of this study was to evaluate the pregnancy rate in ewes after the treatment with different hormones and fixed time artificial insemination. Methods: The ewes were randomly divided in 4 (n=4) groups: Melatonin group (Group 1), Melatonin and Medroxyprogesterone group (Group 2), Medroxyprogesterone group (Group 3) and control group (Group 4). Pregnancy rate, estrus induction rate and litter size were determined and compared. Result: The estrus induction rate in our study was 100% for the first 3 groups and 6.25% for the 4th group. The pregnancy rate was between 4.16% (group 4) and 95.83% (group 2). For the others groups the values were 89.58% for the first group and 91.67%, for the 3rd group. The prolificacy rate was between 1 (control group) and 1.71 (2nd group), with intermediate values for the other 2 groups: 1.21 for 1st group and 1.27 for the 3rd group.