Off-Season Reproductive Performance of Tsurcana Ewes Under Five Estrous Induction Protocols with Different Hormonal Profiles.

The low profitability of small-scale dual-purpose (milk-meat) farming has caused the decline of Tsurcana sheep, making hormonal reproductive optimization essential to sustain Tsurcana sheep farming. We aimed to identify an effective protocol for out-of-season estrous induction in Tsurcana micro-farms. Five protocols were tested in multiparous ewes under free-range conditions (n = 100; 20/group): T1-prostaglandin F₂α (PGF₂α) on day 9/gonadotropin-releasing hormone (GnRH) on day 12; T2-PGF₂α on day 9/pregnant mare serum gonadotropin (PMSG) on day 11; T3-PGF₂α + PMSG on day 9/GnRH on day 12; T4-PGF₂α on day 12/PMSG on day 13; T5-PMSG on day 13. The fluorogestone acetate (FGA) sponges were removed on day 9 (T1-T3), day 12 (T4), or day 13 (T5). The estrous responses (70-100%) mainly occurred 36-48 h post-sponge removal, with no differences between protocols or time points. The sponge losses (≤10%) were similar among groups. The occurrence of vaginitis differed significantly between the groups (p = 0.008) and was restricted to the long-duration treatments (T4 and T5; ≤10%). Singleton births predominated, the twinning rate was modest (highest in T1-T3), and no multiple births occurred. The lambing, singleton, twinning, and prolificacy rates, as well as birth weights, showed no significant differences between the groups. The estrous responses correlated strongly with the pregnancy, lambing, and singleton rates (Kendall's τ = 0.82, p < 0.05). Cost analysis identified T1 as the most efficient protocol. Short-duration sponge retention combined with PGF₂α and GnRH (T1) provides the optimal reproductive results for sustainable Tsurcana micro-farming.