REPRODUCTIVE RESPONSE OF NULLIPAROUS AND MULTIPAROUS EWES UNDER DIFFERENT NATURAL MATING METHODS

This study compared different natural mating (NM) management methods in nulliparous and multiparous ewes. Santa Inês ewes (n = 236) were allocated according to their parity (66 nulliparous and 170 multiparous) to controlled (C) or free (F) NM management for 35 days, using the same rams (n = 10): NM-C0 – one mating at estrus detection (T0); NM-C12 – one mating 12 hours after T0 (T12); NM-C0-12 – two matings, at T0 and T12; and NM-F – free mating from 18:00 to 06:00 h. Reproductive performance was evaluated based on mating rate (MR), conception rate (CR), lambing rate (LR), multiple birth rate (MBR), prolificacy (P), and fecundity rate (FR). Mating management did not affect the performance of nulliparous ewes; however, it influenced CR and LR in multiparous ewes: NM-C0-12 showed higher CR and LR (95.00% and 95.00%) than NM-C0 (73.33% and 75.55%), while NM-F resulted in higher LR (90.50%) than NM-C0 (75.55%). Parity affected ewe performance under specific mating management methods. In NM-C0-12, nulliparous ewes showed lower MR, CR, LR, and FR than multiparous ewes (83.33 vs. 100%; 61.11 vs. 95.00%; 61.11 vs. 95.00%; and 0.78 vs. 1.40, respectively). In NM-F, nulliparous ewes also had lower LR, MBR, and FR than multiparous ewes (64.70 vs. 90.50%; 11.76 vs. 45.24%; 0.76 vs. 1.38, respectively). In conclusion, the mating management methods involving two matings 12 hours apart or free mating improves the reproductive performance of multiparous ewes, whereas nulliparous ewes perform better under a single mating, either at estrus detection (NM-C0) or 12 hours later (NM-C12).