Factors influencing pregnancy rate and loss after laparoscopic artificial insemination with frozen-thawed semen in Lohi sheep under sub-tropical conditions.

Abstract

This study evaluates factors influencing pregnancy rates per artificial insemination (P/AI) and pregnancy loss in Lohi ewes undergoing laparoscopic AI with frozen-thawed semen under sub-tropical conditions. Data from three experiments comprising ewes (n&#x2009;=&#x2009;358) of mixed parity (nulliparous; NP and parous; P), various body condition score (BCS) and assigned to long-term (LTP, 11&#x2009;days) and short-term (STP, 5&#x2009;days) oestrus synchronization regimen across high breeding season (HBS) and low breeding season (LBS) were analysed. Laparoscopic insemination was conducted 54&#x2009;h post-sponge removal. Pregnancy diagnosis and loss were evaluated on days 35 and 90 post-insemination via ultrasonography. Results showed parity significantly influenced P/AI, with nulliparous ewes achieving higher pregnancy ratios than parous ewes (p&#x2009;=&#x2009;.001). BCS significantly influenced P/AI (p&#x2009;<&#x2009;.05), with a quadratic relationship observed between BCS and season (BCS*BCS*Season; p&#x2009;=&#x2009;.07). Progestin treatment did not significantly influence the ratio of pregnant ewes (p&#x2009;=&#x2009;.07). Pregnancy losses were significantly higher during LBS than HBS (p&#x2009;<&#x2009;.05), irrespective of progestin treatment. In conclusion, parity and BCS significantly influenced P/AI, with BCS demonstrating a quadratic association with season. Ewes bred during LBS experienced higher pregnancy losses than HBS, irrespective of progestin treatment.