VGO 511: Veterinary Andrology and Reproductive Techniques (1+1)

STORAGE OF FROZEN SEMEN

• The frozen semen straws should always be kept submerged in liquid nitrogen in liquid nitrogen container.

For this the level of liquid nitrogen should be maintained a minimum of 15 cm and above.

• The semen containers should be periodically topped with liquid nitrogen.
• The semen straws should be kept in a plastic goblet which in turn should be kept in canister.
• The goblet should not be tightly packed with semen straws.
• There should be space for liquid nitrogen to go inside to maintain the temperature at lower level.
• Always keep identification slip or colored plastic sticks in the goblet.
• The slip or stick should contain the information about the semen straws for easy and quick identification.
• Don’t keep different breeds’ semen straws in a goblet. The semen straws of same breed but from different bulls should be stored with proper partition.
• The goblets used must be slightly shorter than straws to enable quick removal of straws. The commonly used goblets are 12 cm in height.
• A 35 mm diameter goblet holds 85 medium straws and 65 mm goblet holds 300 medium straws.
• The frozen semen should never be touched with hands. The straws should always be removed with pre-cooled stainless steel forceps.
• Frozen semen is exposed to elevated temperature when the semen is transferred or taken from a storage container.
• The increase of temperature is determined by length of time exposed, ambient temperature, air circulation, solar radiation, level of liquid nitrogen in container and height to which the canister is raised above the neck.
• The technician must be efficient enough to pick desired straw within 10 seconds.
• This will minimize the fluctuation in temperature of straws while handling.
• If semen is to be transferred from one canister to other, keep both the canisters submerged in liquid nitrogen kept in a thermocool box and carry out the transfer quickly.
• During storage and handling of frozen semen, any rise in temperature above -130 ⁰ C should be avoided.
• The key factor enabling the successful long term storage of frozen semen is low temperature.

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