Storage containers for frozen semen and its effect on sperm cryo-survival

Abstract

The increasing use of cryopreserved semen for artificial insemination (AI) has stimulated the demand and development of better cryoprotectants, diluents, freezing protocols (cooling, freezing and thawing rates) and storage containers, in order to keep the semen characteristics, thus ensuring the preservation and marketing of the sperm in optimal conditions, facilitating its use in the field. There are different types of containers used for freezing semen, such as 0.25mL and 0.5mL straws, presenting good transmission temperature from the outside to the inside, but its small volume makes it necessary to use various samples to complete the insemination dose; maxi-straws of 4 and 5 mL, have a cryobiologically unsuitable shape because they do not allow the transmission of a uniform temperature across the sample, facilitating the recrystallization and damage to the sperm. The use of Flatpacks for freezing boar semen has shown better results in sperm motility and membrane integrity post-thawing than other containers, probably due to the better transmission of temperature and heat dissipation through the sample, contributing to dehydration and more homogeneous formation of ice crystals.