The effect of freezing rate on motility and GOT release of frozen goat spermatozoa
Twelve pooled semen samples from mature bucks were used. Split samples were washed once, then diluted to 400 x 10 6 spermatozoa/ml with Tris-citric acid yolk diluent. After cooling in 60 min. to 5¦C, an equal volume of glycerated diluent was added in three aliquots at 10 min. intervals. Final glycerol concentrations were 0 percent, 4 percent and 7 percent. Three freezing rates were used: slow, intermediate and fast; 30, 10, 7 min., respectively to -80¦C. Internal straw temperatures were measured. After freezing, straws were dropped directly into liquid nitrogen. Three equilibration rates included 0, 1 and 2 hours after glycerolization. Progressive motility and extracellular glutamic oxalacetic transaminase (GOT) were estimated at prefreeze, post-thaw and post-stress (3 hours post-thaw at 37¦C). Straws were thawed at 75¦C for 5 sec. There was a significant loss of glycerol. When negative effects on prefreeze motility were removed, equilibration resulted in a lower mean loss of motility between prefreeze and post-thaw. GOT release during freezing/thawing was lower for 2 h equilibration than for no holding time. This was most significant for 4 percent glycerol. An interaction between equilibration and freezing rate indicated that GOT release was greatest when semen was not equilibrated and fast frozen. Stress GOT release was higher for semen frozen just after glycerolization than for other treatments. Faster freezing rates resulted in less damage to the spermatozoa than slow rates . The only statiscally significant advantage for fast freezing was for post-thaw motility when 7 percent glycerol was used
| Main Authors: | , , , , |
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| Format: | Texto biblioteca |
| Language: | eng |
| Published: |
Scottsdale, AZ (EUA)
1982
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