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 = 358) of mixed parity (nulliparous; NP and parous; P), various body condition score (BCS) and assigned to long‐term (LTP, 11 days) and short‐term (STP, 5 days) oestrus synchronization regimen across high breeding season (HBS) and low breeding season (LBS) were analysed. Laparoscopic insemination was conducted 54 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 = .001). BCS significantly influenced P/AI ( p < .05), with a quadratic relationship observed between BCS and season (BCS*BCS*Season; p = .07). Progestin treatment did not significantly influence the ratio of pregnant ewes ( p = .07). Pregnancy losses were significantly higher during LBS than HBS ( p < .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.