摘要：This experiment was carried out to develop a new extender for long term preservation of equine sperm at 5°C. Semen was collected from 4 riding horse stallions by means of an artificial vagina and filtered through gauze. Gel-free semen was diluted 2 to 3 times with a pre-extender and then centrifuged (450 × g, 10 min). Precipitated spermatozoa were suspended in the extender for preservation to give a final sperm concentration of 1 × 10 8/ml and stored at 5°C for 72 hr. Sperm motility was examined every day. Preserved equine spermatozoa in Modena extender (developed for boar semen preservation at 15°C) containing egg yolk maintained more superior motility than those in some other boar semen extenders during the storage at 5°C (p<0.05). As additives to equine semen extender, Casein was a very beneficial protein as compared with BSA, Ovalbumin and Livetin (p<0.05). Two %Casein extender which was made based on the Modena was superior to Martin, Kenney and CGH-27 extender for maintaining the viability of equine sperm, and was further improved by the addition of 5%egg yolk. The conception rates for semen stored in Casein-egg yolk extender at 5°C were 63.6% (14/22) within 0-72 hr and 75% (3/4) within 96-120 hr of storage, respectively. The total conception rate for semen preserved for up to 120 hr at 5°C was 65.4% (17/26). We have named this new casein-yolk extender (see in Table 5) ‘Iwate extender’.
