| Siberian tiger is first-grade state protected mammals in China and the total number of wild Siberian tiger is seldom today.The inbreeding phenomenon occurred often in Siberian tigers of artifical breeding.The study of cryopreserve sperma in Siberian tiger could allow to found long-range banking of gene pools in the future as well as promote gene flow between captive and wild population,hedging against losing more genetic variation and have more effect to protect it.An Electroejaculation technique was applied to the Siberian tiger for semen collection and characterization of their seminal traits,and the semen were recovered from 23 of 17 tigers.The results show different voltage was suitable for the electro of the different individuals.Ejaculation was happened on the mean of 4.78±1.3V.The mean values of ejaculation were:volume,4.02±1.18mL;pH,7.05±0.26;sperm concentration,23.4333.87x106/mL;motility,62.9±19.96％;abnormal sperm percentage,45.06+14.96％.As a whole,the efficiency of eletroejaculation was best in December and January,accounting 57.2％of all the rate of producing seminal fluid containing spermatozoa in a year;it was worst in October and November,that accounting 44.4％of all the rate of aspermia in a year.That state seasonality has effect on semen strait.The effect on protecting of spermatozoal motility was compared by using these different cryoprotective diluent with fructose extender and glucose extender in this study.These results demonstrate that the fructose diluent is better than the glucose one in post-thaw motility of 58.85 and 13.83％,abnormal sperm of 58.88±11.88％and 63.1±1.7％,intact acrosome of 82.43±4.04％and 83.1±8.3％,respectively.Spermatozoal structure was observed by transmission electron microscope,scanning electron miceoscope and light microscope in the study.The spermatozoa total length is 53.424±0.7μm,and consist of the head and the tail.Cytoplasmic droplets can be seen in the distal or proximal position or the midpiece,including mitochondria of tiger spermatozoa.The head:rounded in shape and length 3.98±0.58μm,width 3.41±0.59μm.The nick:length 0.66±0.106μm,including of centriole and segmented columns.The middle piece of the tail is 8.627±1.166μm.Its axonemal complex have an usual "9+2" pattern.;its mitochondria makes 31-34 turns.The principal and terminal piece of the tail is 39.31±1.25μm.The cryodamage was observed in the cell membrane and mitochondria.All of these changes were found to contribute to a general decline in post-cryopreservation semen fertility.The plasma membrane was expanded extremely or broken and the acrosome was vesiculatcd or dispersed while plasma membrane and acrosome seldom lost.Thus,cryoprotectivc diluent could protected sperm in partly,and the sperm cryodamage could be not avoided.
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