Abstract:
OBJECTIVE : To evaluate the effect of cooling rates, selenium
supplementation, and three semen extenders on cooled and frozenthawed
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.
