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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 °C and frozen at -196 °C 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.

Objective: To determine the effect of oral selenium supplementation and semen collection methods on various post thaw semen quality parameters in Saanen bucks. Methods: Sixteen healthy bucks were divided into two equal groups (n=8 each). The treatment group received selenium at 10-day intervals for three months. Sperm kinematic parameters, morphological parameters, mitochondrial membrane potential, plasma membrane functionality, and sperm DNA integrity were evaluated weekly pre and post-cryopreservation. Results: The mean percentages of the morphological abnormalities were significantly lower in the selenium-supplemented samples when semen was collected by using artificial vagina method (P<0.05). Proximal droplet defects were significantly lower in the selenium supplementation group when semen was collected by electro-ejaculation (P<0.05). Post-thaw sperm parameters such as total motility and progressive motility were significantly higher when semen was obtained by artificial vagina in the selenium-supplemented bucks compared to the electro-ejaculation and the control groups (P<0.05). The sperm kinematic parameters such as curvilinear velocity, average path velocity, and amplitude of lateral head displacement were significantly higher when semen was collected by artificial vagina in the selenium-treated bucks (P<0.05). The percentages of sperm with intact and functional plasma membrane and functional mitochondria were significantly higher in the selenium-supplemented samples collected with artificial vagina compared to the electro-ejaculation method and the control groups (P<0.05). In vitro fertilizing potential was significantly higher in the selenium-supplemented samples collected with artificial vagina compared to the electro-ejaculation method and the control groups, respectively (P<0.05). Conclusions: Oral supplementation of selenium and artificial vagina semen collection improve post thaw sperm quality parameters of Saanen buck.