Comparison of storage techniques for giant panda sperm

Abstract

AbstractSemen storage for artificial insemination is an integral part of giant panda captive breeding programs. The development of short‐ and long‐term storage techniques is needed to ensure a viable reserve of germplasm for artificial reproduction. In this study semen collected by electroejaculation from three male pandas was extended in culture medium prior to recording initial motility (MOT), speed of progression (SOP), and percent live (% L). Motility scores (MS) were calculated as MOT×SOP2. All results were expressed as % of initial MS (% IMS) and % of initial L (% IL). Experiment 1 examined the longevity of cooled sperm, both fresh and thawed. Extended fresh sperm was diluted in TEST‐Y buffer before storage at 4°C. The % IMS and % IL were recorded at 4, 8, 24, and 48 hr for males 1 and 2, and at 29, 70, and 214 hr for male 3. Additional sperm was frozen over liquid nitrogen vapor following dilution in TEST‐Y buffer with 4% glycerol and cooling to 4°C. The % IL of fresh sperm after 48 hr at 4°C was 96 and 100 for males 1 and 2, respectively. In contrast, thawed sperm from these males exhibited just 77 and 68% IL at thaw (T0). These data indicate that short‐term liquid storage is superior to freezing when sperm is to be used within 48 hr of collection. Experiment 2 compared the effects of four cooling methods on the cryosurvival of panda sperm. Sperm from male 3 was diluted in TEST‐Y buffer with 4% glycerol and cooled by four methods. Vials were frozen over liquid nitrogen vapor and stored for 5 months in liquid nitrogen. The sperm was thawed and evaluated for % IL at T0, and then reevaluated at 30 and 60 min at 37°C. There was no significant effect of the prefreeze cool method on % IMS or % IL. Zoo Biol 22:335–345, 2003. © 2003 Wiley‐Liss, Inc.