Dear Dr. Taymour,

The BASIC answer is: traditionally "TRIS".

P.S.: Please see my THESIS (PhD) within my Publication list (see the pdf attachment, the WHOLE thesis, therein),

Regards,

Omer

dear dr Omer thanks a lot I will see it 

Details of PhD Thesis:

CRYOPRESERVATION AND ACROSOME REACTION OF DOG SPERMATOZOA

(May 2000, Bristol Univ., Bristol-U.K.)

1- p. 187:

as 3-6. DISCUSSION

(for "OPTIMISATION OF FREEZING REGIMENS FOR DOG SPERMATOZOA")

2- p.232:

as GENERAL DISCUSSION

3- p. 279:

(within APPENDIX)

as 2-2 Tris extender (the "content" of the extender CHOSEN/USED).

for CRYOPRESERVATION;

Recommended protocol:

Step-wise (three-step) freezing (using programmable biological freezing), and eventually followed by traditional thawing; at around body temp (35 degrees C) for 1 min.

From the Thesis Abstract:

"The optimal freezing regimen (from +4°C to -120°C) was determined by using a programmable biological freezer in a series of experiments, in which various cooling rates were combined in a Latin square designs. Semen was diluted in standard Tris extender containing 20% egg yolk and 2% glycerol (v/v, final) and packed in 0.25 ml French paiettes (straws). The optimal cooling regimen was -0.5°C/min from +4°C to -9°C, -40°C/min to -20°C, -100°C/min to -120°C, followed by direct immersion of the straws in liquid nitrogen".

In connection with the storage and freezing of semen of dogs, our developments are for a period of 30 years. In response to your question, we express the following opinion. Our experience shows that freezing the semen of dogs in vials of 0.5 ml with Tris fructose medium, in the presence of a low concentration of glycerol, gives good results after thawing. Over 40% of sperm with good motility and velocity parameters after thawing. When carrying out double deep cervical insemination, results show more than 60% fertilization.

thanks Dr Maria  ivanova- Kicheva

Omer Ucar , do you think that the lower glycerol concentration is possible due to the use of 0.25 ml straws? Or could be used also for 0.5 ml straws?@@

What is the best method for freezing

Dear Alessandra,

Regarding your question, we used small size (0.25 ml) straws along with 2% glycerol (v/v), final. for semen freezing. Whether the size (0.5 vs 0.25 cc) matter with low dose (2%) glycerol? I DO NOT know the actual answer, yet it is someting related with "surface area" of the package (straws) in varying sizes. BUT, it is worth seeing the actual relationship between the size of straw and glycerol concentration upon sperm survival post-thaw. Just give a try. Actually, we did NOT test it in our PhD study.

Regards, Omer