author(s)
RA Legha, TR Talluri and Yash Pal

abstract
Advances in artificial insemination (AI) techniques and semen handling have led to an increased rate of successful pregnancies and increased efficiency in large-scale breeding programs. AI with frozen Jack’s semen is an important aspect in production of superior mules. Various studies in other species indicated that thawing temperature and duration play significant role in post-thaw motility. The following study aims to determine the optimal temperature for thawing extended cryopreserved ejaculated semen and a trial was conducted on different thawing temperatures and time durations to study its effect on post-thaw sperm motility. Five exotic jacks maintained at Equine Production Campus, NRCE, Bikaner were utilized for semen collection and its preservation. Citrate- EDTA and Lactose glucose-EDTA–Egg yolk were used as primary and secondary extenders, respectively for semen cryopreservation. Ejaculated jack semen collected by means of an AV and cryopreserved in 0.5ml straws and thawed at different temperatures. PTM was observed as 43.48, 51.4 and 47.8% for thawing of frozen semen straws at 37 °C for 30 sec, one min and two min, respectively. At 50 °C water bath temperature for 15 sec, 30 sec and one min, post thaw motility was 32.6, 23.2 and 18.6% respectively. Similarly, at 70 °C water bath temperature for 5 sec, 10 sec and 15 sec, the post thaw sperm motility observed was 44.40, 18.75 and 17.4%, respectively. It is concluded that the optimum post thawing temperature for cryopreserved jacks’ semen is 37 °C for one min. However, it can also be thawed satisfactorily at 37 °C for 30 sec or 2 min and at 70 °C for 5 sec only as there was no significant differences (p≤0.05) were observed in liveability and motion characteristics. The present study infers that the thawing temperature and its duration does affect the motility of cryopreserved jack semen.