Overall, semen backflow was observed in none, one,and more than one insemination in 72.4% (432/597), 22.1%(132/597), and 5.5% (33/597) of the sows, respectively.The FTPCAI1 sows with semen backflow in one AI andthe MultPCAI sows with semen backflow in at least twoAIs had lower odds of farrowing (P < 0.05) compared withsows without semen backflow. However, the occurrence ofbackflow during insemination had no influence on farrow-ing rate (P > 0.05) in FTPCAI2 sows (Table 3). The presenceof backflow in the single AI performed in FTPCAI1 sowsreduced their litter size (Table 3), whereas a smaller littersize was observed in MultPCAI sows when backflow waspresent in at least two inseminations (P < 0.05).Eighteen sows (3.0%) bled during insemination, 7 and11 from the FTPCAI2 and MultPCAI groups, respectively.Higher odds of farrowing (P < 0.05) were observed in sowswithout bleeding than in those with bleeding duringinsemination in both MultPCAI (92.5% vs. 81.8%) and FTP-CAI2 (93.7% vs. 71.4%) sows. Litter size was not influenced(P > 0.05) by bleeding during insemination in MultPCAI sows (12.8 ± 0.4 vs. 13.0 ± 1.0 piglets) or in FTPCAI2 sows(12.6 ± 0.2 vs. 12.3 ± 1.4 piglets).