Energy, Hormones, and Performance: How Do Dairy Rams Cope with the Breeding Season?

This study evaluated reproductive performance, metabolic and hormonal fluctuations in Sarda rams raised under semi-extensive management conditions during the breeding season. Fourteen rams were isolated from ewes, subjected to nutritional flushing, and treated with melatonin implants (3X18 mg) before joining the flock. From June to December, body condition score (BCS), NEFA, urea, triglycerides, cholesterol, testosterone, fecal thyroid hormone metabolites (FTMs), and fecal corticosteroid metabolites (FCMs) were measured every 45 days. Ewes’ pregnancy rates (PR) and conception dates were determined by reproductive ultrasound scanning to estimate rams' 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 concentrations peaked (p<0.05), whereas triglycerides and urea reached the lowest levels (p<0.05). FTMs peaked in November and June (p<0.05). Testosterone concentrations were three-fold higher in June than the rest of BS (p<0.05), while overall PR was stable during the BS. Despite metabolic and endocrine changes, rams maintained reproductive efficiency, indicating an interaction between metabolic status, stress response, and reproduction, and supporting the need for targeted management strategies to sustain welfare and long-term performance.