Metabolic, Hormonal and Body Condition Changes in Melatonin-Implanted Dairy Rams and Flock Pregnancy Rate During the...

Reproductive activity imposes significant physiological demands on rams. This study evaluated metabolic and hormonal fluctuations in Sarda rams under semi-extensive management conditions, together with flock reproductive outcomes. Fourteen rams were isolated from ewes, subjected to nutritional flushing, and treated with melatonin implants (3 × 18 mg) before joining the flock. From June to December, body condition score (BCS), non-esterified fatty acids (NEFA), urea, triglycerides, cholesterol, testosterone, faecal thyroid hormone metabolites (FTMs), and faecal corticosteroid metabolites (FCMs) were measured every 45 days. Ewes' pregnancy rates (PRs) and conception dates were determined by ultrasound scanning to estimate flock reproductive performance. BCS declined (p < 0.05) from June (3.11 ± 0.06) to November (2.80 ± 0.06). In November, NEFA, cholesterol and FCMs peaked (p < 0.05), whereas triglycerides and urea reached the lowest levels (p < 0.05). FTMs peaked in June and November (p < 0.05). Testosterone concentrations were three-fold higher in June than the rest of the mating season (p < 0.05), while overall PR was stable. Despite metabolic and endocrine changes in rams, overall flock reproductive performance remained stable. The final stage of mating season may represent a strategic period for targeted management strategies to sustain welfare and long-term performance.