Cervical artificial insemination with frozen-thawed semen in sheep: the secret is in the cervix of Norwegian ewe breeds†

In sheep, cervical artificial insemination (AI) of frozen-thawed semen is not practiced worldwide due to the unacceptably low pregnancy rates achieved (typically <30%). The exception to this is in Norway where farmers perform shot-in-the-dark vaginal AI with frozen-thawed semen and achieve pregnancy