A total of 121 European fallow deer does, being either parous (n= 15) or nulliparous (n= 106), were treated with intravaginal progesterone impregnated controlled internal drug release (CIDR) devices for 14 days. The does were divided into three treatment groups and inseminated in utero by laparoscopy, at approximately 65 hours after CIDR device removal, with 25 × 106 fresh Mesopotamian (n= 40), 25–35 × 106 frozen-thawed Mesopotamian (n= 41) or 30–32.5 × 106 frozen-thawed European (n= 40) fallow deer spermatozoa. The semen used had been collected, from two Mesopotamian and two European fallow deer bucks, by electroejaculation under general anaesthesia. Pregnancy was diagnosed by rectal ultrasonogrdphy on Day 50 after insemination.

There were no apparent differences in the quality of ejaculates between the two subspecies of fallow deer. The volume of semen and the total number of spermatozoa ranged between 0.6–1.2 ml and 2.11–4.95 × 109 per ml of semen, respectively. Evaluation of frozen-thawed spermatozoa revealed post-thaw motility rates between 50–70%. The overall conception rate was 65.3%. A higher conception rate was observed following insemination with European than Mesopotamian frozen-thawed spermatozoa (75% vs. 53.7%, respectively, P < 0.05). Insemination with fresh Mesopotamian spermatozoa increased the conception rate to a level not significantly different from that observed following insemination with European frozen-thawed spermatozoa (67.5% vs. 75%, for fresh Mesopotamian and frozen-thawed European semen, respectively).