Effects of melatonin implants on hormone profile and mating behaviour in rams

Abstract

Objective: This study investigated the effects of melatonin implants on the mating behaviours and hormone concentrations of melatonin (MEL), GnRH and testosterone (TES) before the breeding season were investigated in Tahirova rams. Material and Methods: Six rams were used for hormone analysis. For the sexual behaviour test, six rams were mated with 69 ewes. The rams’ sexual behaviour was tested for 10 minutes.18 mg of melatonin implants were inserted into half of the rams and ewes. Three pellets were inserted into rams and one pellet for females. MEL, GnRH, and TES hormone analyses were performed by the ELISA method from the blood serum of the rams before implanting (Day 0) and 21, 42, 63, 94 and 129 days after implant. Results: Results showed that melatonin implantation significantly reduced MEL hormone concentration in Tahirova rams (P≤0.05). MEL concentration decreased to its lowest concentration on Day 63 in the treatment (T) group and differed significantly from the control (C) group (P≤0.05). While GnRH and TES hormone concentrations were similar between the groups, TES hormone concentrations in the C group differed according to the observation days (P≤0.05). Ano-genital sniffing, foreleg kicking, and tongue flicks behaviours were observed at a higher frequency in the T group than the C group (P≤0.05). While rams in group T had 64.8% mating efficiency, rams in group C had 86.9% mating efficiency (P≤0.05). Conclusion: The administration of subcutaneous melatonin implants before the breeding season in Tahirova rams, which induced a significant decrease in the MEL hormone concentration, is important in increasing sexual behaviours. Keywords: Tahirova sheep, GnRH, testosterone, negative response, sexual behaviour, mating efficiency