Fertilization and Embryonic Loss in Sheep after Insemination with Deep Frozen Semen

Abstract

ALTHOUGH there are reports of satisfactory lambing after artificial insemination with frozen ram semen^1–4, most investigators have obtained disappointing results (reviewed by Emmens and Robinson⁵ and Sadleir⁶). It has been claimed⁷ that frozen ram spermatozoa penetrate to the cranial part of the cervix more slowly than those from fresh semen. In an experiment⁸ with a limited number of animals, cervical insemination yielded only unfertilized eggs (eight ewes), and although after tubal insemination fertilized eggs were recovered from all three ewes examined, only two out of seven ewes lambed. We have conducted two experiments with frozen semen—the first at the McCaughey Memorial Institute, Jerilderie (Table 1) and the second on a private property at Yass, NSW (Table 2).