Assessment of sexual activity in rams stimulated with artificial light and its impact on unstimulated rams during the initial 14 days of male effect

Seasonal anoestrous reduces reproductive efficiency in sheep in temperate regions. Artificial photoperiod manipulation is a non-hormonal approach that stimulates ram sexual activity and enhances the "ram effect" on ewes. This study evaluated the sexual behaviour of rams subjected to artificial long-day photoperiods (L group) and their effect on non-stimulated rams (C group) during the first 14 days after introduction to anoestrous ewes. Eleven rams were assigned to photostimulated (n = 6) or control (n = 5) treatments, forming four groups: L, C, L+C (stimulated rams exposed to controls), and C+L (controls exposed to stimulated rams). Continuous video recording documented 5707 behavioural events. Photostimulated rams (L) exhibited higher activity (mean = 747.7 behaviours/ram) than other groups (C+L: 519.5; L+C: 443.0; C: 365.3; p < 0.01), with anogenital sniffing, approaching and chasing ewes being the most frequent behaviours. Activity peaked on days 2–5 post-introduction, mainly in the afternoon. Control rams housed with stimulated rams were more active than isolated controls, suggesting a social facilitation effect. These findings confirm that photoperiod manipulation enhances ram sexual activity and may influence non-stimulated rams through social interaction, as the different groups of animals exhibited distinct types and amounts of activity. • Artificial light increased sexual activity in rams during seasonal anestrus. • Key behaviours were anogenital sniffing, approaching, and chasing ewes. • Control rams with stimulated peers showed intermediate sexual activity. • Afternoon was the peak period for sexual behaviour across all ram groups.