الفهرس 
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Abstract
The present study was designed to investigate centrifugation protocols, type of
diluent, dilution rate, type of cryoprotectant and cooling on post-thaw quality of Arabian
stallion spermatozoa. Semen was collected from four adult pure Arab stallions on a regular
basis (one ejaculate / week/ 10 successive weeks). After collection, semen was evaluated using
conventional methods. Centrifugation protocols were done on gel free fraction (nocentrifugation,
600 xg/ 10,15 min.,900 xg / 10,15 min and 1200 xg / 10,15 min.). Two semen
extenders were used: INRA-82 and modified Kenney’s extender at dilution rates of 1:1, 1:2
and 1:3. Glycerol 5%, dimethyl-formamide (DMF) 5% and glycerol 2.5%+ DMF 2.5% were
used as cryoprotectants. Cooling over a period of 1 hr., 1.5 hr. and 2 hr was practice prior to
freezing. The post-thaw studied parameters were progressive motility, live percentage, total
abnormalities, viability index and plasma and acrosomal membrane integrities. Based on
results of current study centrifugation of stallion semen at 600 xg for 15 minutes before
cryopreservation could overcome the damaging effect of plasma membrane indicated by
significant improvements of sperm characteristics of post-thaw spermatozoa. Dilution of
centrifuged stallion semen with INRA-82 extender at a rate 1:1 could be used for improvement
freezability of spermatozoa. Inclusion of DMF 5% in INRA-82 extender showed a significant
improvement of sperm characteristics of post-thaw spermatozoa. Cooling of stallion semen to
+50C over a period of 1.5 hr before freezing reduced damaging of spermatozoa, counteract
cold shock and showed a significant improvement of sperm characteristics of post-thaw
spermatozoa. Not only the protocol of freezing of stallion spermatozoa, but also individual
variation in stallions crucial to achieve the desired goal for freezing of stallion spermatozoa.