Single fixed-time artificial insemination in gilts and weaned sows using pLH at estrus onset administered through vulvar submucosal route

This study evaluated the use of a single fixed-time artificial insemination (FTAI) in gilts and weaned sows using 2.5 mg of porcine luteinizing hormone (pLH) administered through vulvar submucosal route, at the onset of estrus. In experiment 1 (Exp.1), 318 pubertal gilts were assigned to two groups: control-G—no hormonal application and artificial inseminations (AIs) at 12, 36, and 60 hours after the onset of estrus if they were still in standing estrus; and FTAI-G—use of pLH at the onset of estrus and a single FTAI 12 hours later. In experiment 2 (Exp. 2), 309 weaned sows were assigned to three groups: Control-S—no hormone application and AIs at 0, 24, and 48 hours after the onset of estrus if they were still in standing estrus; FTAI-NH—no hormone application and a single FTAI at 24 hours after the onset of estrus, and FTAI-pLH—use of pLH at the onset of estrus and a single FTAI 24 hours later. Transabdominal real time B-mode ultrasonography was performed to determine whether the insemination had been performed within 24 hours before ovulation, considered as the optimal interval. In Exp. 1, ultrasound evaluation (12-hour intervals) was carried out to determine the interval between the onset of estrus and ovulation. In both experiments, 2 × 109 sperm cells in 80 mL were used to perform cervical and postcervical deposition of semen in gilts and sows, respectively. Compared with control-G, FTAI-G gilts had shorter (P