Evaluation of the Effects of Melatonin Implants on Testicular and Spermatic Parameters of Rams Raised in Station in the Niayes Zone in Senegal

Abstract

The intensification of livestock production in response to the growing demand for animal products is increasingly creating new challenges in terms of control of livestock management and feeding, and especially reproduction. Also, ewes are often considered responsible for infertility problems in a sheep flock, as the reproductive capacity of rams is often taken for granted. However, it is important to have genetically superior males to improve the overall fertility of the herd. And, one way to control the sexual performance of rams and improve their fertilizing capacity, is to have them undergo melatonin treatment. The objective of this study was to evaluate the effects of the use of melatonin implants on testicular and spermatic parameters of rams raised in stations in the Niayes area of Senegal. The experimental herd consisted of 6 rams of well-known body characteristics which were followed for 2 months during which testicular measurements were carried out at the beginning and semen was collected by electroejaculation every 2 weeks. After a break of 2 weeks, the same rams are implanted with melatonin (MELOVINE ®) at a rate of 3 implants/ram, i.e. a dose of 54 mg of melatonin per ram, and the same measurements and semen collections are again carried out for 2 months. Data on antero-posterior testicular diameter, testicular weight, scrotal circumference, and semen analysis (volume, color, appearance, mass and individual motility, concentration, morphology) recorded and processed with Excel were exported to the SPSS software where they were subjected to descriptive statistical analysis and independent sample comparison testing. The results showed that melatonin treatment significantly reduced weight (555±155 g vs. 396±128 g) and antero-posterior diameter (23.42±2.0 cm vs. 20.10±2.26 cm). However, it induced improvements in ejaculate volume, color, and appearance, sperm production, and morphological abnormality rate, and, most significantly, sperm motility (2.1±1.5 vs. 3.3±1.2) and survival rate (54±34% vs. 80±31%) of spermatozoa. Melatonin has therefore improved the sperm characteristics of rams, and is an interesting reproductive management tool for improving the productivity of sheep farms. It can be recommended for use in artificial insemination centres in order to improve the characteristics of the semen doses produced.