Dietary selenium supplementation, clarified egg yolk extender and slow cooling improve cryopreserved sperm characteristics of Saanen buck

Objective:To evaluate the effect of cooling rates,selenium supplementation,and three semen extenders on cooled and frozen-thawed Saanen buck sperm.Methods:Twenty Saanen bucks were divided into two groups:the selenium supplemented group and the control group.Ejaculates were collected once weekly by artificial vagina.The first experiment examined the effects of cooling rates and selenium supplementation on semen characteristics of Saanen bucks.Pooled semen was diluted with triladyl extender and split into two aliquots for slow and fast cooling.The second experiment explored the effect of selenium supplementation and semen extenders on post-cryopreserved sperm quality.Ejaculates from each group were divided into three aliquots and diluted with three extenders(i.e.clarified egg-yolk,whole egg yolk,Tris without egg-yolk extenders).All samples were cooled for 2 h at 4℃and frozen at-196℃for 24 h.The sperm characteristics such as sperm motility,acrosome integrity,normal morphology,and viability were evaluated by using a phase-contrast microscope.Results:In the first experiment,all sperm characteristics were significantly increased in selenium supplemented samples when slow cooling was used(P<0.05).In the second experiment,in cooled semen,sperm motility and viability were significantly increased in both clarified egg yolk and Tris without egg yolk extenders in selenium supplemented samples as compared with whole egg yolk extender,respectively(P<0.05).After freezing-thawing,all sperm parameters of selenium supplemented samples in clarified egg yolk extender were significantly greater than those in Tris without egg yolk extender(P<0.05).However,normal morphology and acrosome integrity of selenium supplemented samples in whole egg yolk extender were similar to those of selenium supplemented samples in clarified egg yolk extender.Conclusions:The characteristics of cooled and post-cryopreserved sperm are greater when clarified egg yolk extender is used in semen from selenium supplemented bucks.

Semen collection methods and cooling rates affect post-thaw sperm motility and kinematic parameters of Saanen goat

Objective:To evaluate the effects of semen collection methods and different cooling rates on cooled and frozen-thawed Saanen goat semen.Methods:Twenty bucks were divided into two groups of 10 animals per group based on semen collection methods:artificial vagina and electro-ejaculator.Samples from each collection method were pooled and diluted with Tris-based extender.The pooled semen was divided into two cooling methods:slow cooling and fast cooling.Sperm motility and velocity,sperm plasma membrane integrity,sperm viability,mitochondrial membrane potential and DNA integrity were evaluated before dilution,immediately after cooling at 4℃and at 24 h after freezing by using computer assisted sperm analyser method and epifluorescence microscope.Results:Mean values for total motility,rapid-speed and progressive motile spermatozoa were significantly higher in semen collected with artificial vagina than electro-ejaculator(P<0.001).Slow cooling resulted in higher percentages of total motile,rapid-speed and progressive motile spermatozoa as compared to fast cooling(P<0.05).The post-thaw percentage of rapid-speed spermatozoa collected by artificial vagina in slow cooled sperm was significantly higher as compared to electro-ejaculator method(P<0.05).The mean values of curvilinear velocity and straight-line velocity were significantly higher in slow cooled semen obtained by artificial vagina(P<0.001).Similarly,the combination of artificial vagina and slow cooling resulted in significantly higher post-thaw percentages of straight-line velocity,average-path velocity,sperm plasma membrane integrity,viability and acrosome integrity(P<0.01).No significant differences were observed in slow cooling between artificial vagina and electro-ejaculator in terms of post-thaw sperm mitochondrial membrane potential and DNA integrity(P>0.05).Conclusions:The use of artificial vagina and slow cooling rate in cryopreservation protocol improves the cooled and post-thaw sperm quality of Saanen buck semen.