الفهرس 
Extenders for cooling and freezing rabbit semenOnly 14 pages are availabe for public view
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Abstract
Ahmed Said Sayed Baky: Impact of some cryoprotectant agents on freezing ability and fertility of rabbit buck spermatozoa. Unpublished master of science Thesis, Animal Production Department, Faculty of Agriculture, Ain Shams University, 2014.
The present work was carried out at Intensive Rabbit Production Unit, belonging to Consulting and Research Center, Faculty of Agriculture, Ain Shams University. The work was designed to investigate characteristics of rabbit semen and its extender to find out the cooling and freezing ability of rabbit semen. Ten mature New-Zealand White (NZW) rabbit bucks were divided into two groups (five each) and two Californian (third group) rabbit bucks with good semen characteristics were selected for this study. Two unreceptive females were used as teaser for semen collection purpose and 60 hybrid females were used for fertility test (30 inseminations for each extender). Semen was collected twice weekly and evaluated, after that, good ejaculates from bucks of each group were pooled together and diluted by added on part semen to five part extender at 37oC. This study includes three experiments: preliminary experiment, cooling for long term storage experiment in different seasons and freezing experiment in different seasons. Preliminary experiment, NZW and Californian rabbit semen and extenders characteristics had been studied, in addition to cooling rabbit semen for 3 hours in nine Tris-citric-glucose-egg yolk based extenders used in this study (DMSO + sucrose, sucrose, glycerol added to semen at 37°C, glycerol added to semen at 4°C, DMSO + glycerol, DMSO, glycerol + sucrose, gelatin and Tris). In cooling for long-term storage experiment, pooled extended semen in Tris (liquid state storage) and gelatin (solid storage) extenders, packed into aliquots and dipped in a cup of water, then stored in a refrigerator at 8ºC. Aliquots were warmed at 37ºC for 30 seconds for evaluation or artificial insemination when needed. In freezing experiment, pooled extended semen in DMSO + sucrose, sucrose, glycerol added to semen at 37°C, glycerol added to semen at 4°C, DMSO + glycerol, DMSO and glycerol +
sucrose packed into 0.5 ml straws after 45-60 minutes at 5oC as equilibration period, then exposure to liquid nitrogen vapour for 8 minutes at subsequent different levels, after that, immersed into liquid nitrogen. Straws were thawed at 37°C for 10 seconds for evaluation or artificial insemination when needed. Preliminary experiment results showed that seminal characteristics of NZW rabbit was better than those obtained of Californian bucks except dead and abnormalities%, extenders which had glycerol had higher osmotic potential and low semen quality (p ≤ 0.05) than other extenders. Sucrose addition to glycerol or DMSO improve semen quality ( p ≤ 0.05) and non-significant difference between breeds for all seminal characteristics. Cooling experiment results showed that, for all characteristics studied; semen extender, storage time, season had very highly significant (P ≤ 0.001) effect on subsequent seminal characteristics. Gelatin extender had better semen quality than Tris (p ≤0.05); although, fertility rate and prolificacy of Tris extender was higher than gelatin extender. Freezing experiment gave the same results obtained from cooling preliminary experiment except breed, which had significant (P≤0.05) effect in this experiment. Glycerol addition temperature had non-significant difference (p ≥ 0.05). Extender had DMSO+ sucrose as a cryoprotectant agents was the better extender in semen quality and fertility rate compared to other extenders. Extender had DMSO + glycerol as a cryoprotectant agent was the worst extender in all characteristics and fertility.
In conclusion, supplementation of cooling rabbit semen extender with gelatin improved diluted semen characteristics and decreased prolificacy and fertility. Glycerol considered as a toxic substance for cooling and freezing rabbit semen. Addition sucrose to glycerol or DMSO improved diluted semen characteristics and fertility. DMSO+ sucrose was good extender for freezing rabbit semen.
Key words:
Cooling, DMSO, Freezing, Gelatin, Glycerol, Rabbit semen, Sucrose, Tris.