Question: Why are poultry/ cock spermatozoa more unsuitable for cryopreservation compared to bull spermatozoa?

Martin Johnsson answered on 18 Mar 2020:

I don’t know, and I’m not sure anyone really knows! There seems to be all these small differences in different animals’ reproductive biology, making for example chicken and pig semen cryopreservation trickier than in cattle.

I looked at a review by Hüseyin Baki Çiftci and Ali Aygun from 2018 about this problem, and they wrote:

“The reason why freezing/thawing decreases the fertility rate of poultry semen is not completely understood, but might be related to the unique morphological and physiological features of poultry sperm cells”

That is, there is something different about poultry semen, and it may have to do with the form and function of the sperm cells, but we don’t know for sure. They discuss some potential explanations:

* Poultry sperm cells have longer tails, and that might be a reason they might take more damage when freezing than bull sperm cells.

* Poultry sperm cells also have a different fact composition in their cell membranes, which might also make them more fragile when freezing.

* Also, for some reason, several compounds used in cryopreservation are toxic to poultry sperm. Again, we don’t really know why.

If you want to, you can check out the paper here: https://www.researchgate.net/publication/327617704_Poultry_semen_cryopreservation_technologies