Influence of Exogenous Melatonin Treatment on the Ram Fertility of the North-east Bulgarian Fine-wool Sheep Breed

Abstract

The potential of the epiphyseal hormone melatonin to effect on seasonally breeding species has been extensively studied, but the data remain inconclusive. Levels of reproductive parameters modulation are important to monitoring, given the breed affiliation, as example analyzed breed, which has a pronounced seasonal type of reproduction. The objective of this study was to determine whether application of exogenous melatonin has an effect on ram fertility of the North-east Bulgarian fine-wool sheep breed, as estimated by the reproductive performances of ewes, in the non-breeding season. In addition, the study quantified the effects of exogenous melatonin on ejaculate volume and concentration of sperm in rams with melatonin implants (n = 5) and per os treated rams (n = 5). The application of exogenous melatonin improves the fertility of rams of the studied breed. As a result of the current study, in the 2nd experimental group there was a positive trend on ejaculate volume and concentration of sperm throughout the experiment compared to control group. Although rams exhibited an improvement in sperm parameters, a significantly increased birth rate was found in sheep mating with male receiving melatonin both through implants (P < 0.05) and per os (P < 0.05). It was found to increase the total percentage of birth lambs in 1st (28%) and 2nd (29%) experimental groups compared to control. The results are guiding for North-east Bulgarian fine-wool sheep farmers and breeders, in terms of opportunities to improve the breeding process and obtain more lambs.