Genetics gains in the wool industry are limited by the need for expensive, surgical artificial insemination to utilise elite male genetics. This is due to the fact that frozen-thawed ram spermatozoa are unable to navigate the ewe’s cervix, precluding use of simple over the rail cervical AI by growers. One reason for this issue is that frozen-thawed sperm are easily attacked by immune cells in the female reproductive tract whereas fresh sperm are not. This study will examine why frozen-thawed sperm doesn’t interact correctly with the immune system and test specific seminal plasma proteins may protect the sperm from neutrophil attack. This research will move the Australian wool industry closer to cheap, effective non- surgical artificial insemination with frozen semen and more widespread use of elite sires.