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![Liquid nitrogen vacuum tanks such as these were created (see NAL #631) to transport frozen bull semen from the sites where it is produced to the farms where it is used, and to store the semen on farms. [In the interest of clarity, one cane was raised to reveal the straws containing semen. However, in practice the straws should be raised above the lid of the tank only in the process of thawing the semen or for rapid transfer to another tank. The temperature of frozen semen rises rapidly when the straws are held even briefly above the lid of the tank, causing irreversible damage to the sperm when the temperature falls as the straws are returned to the tank.] A cross section of a typical tank reveals an insulated double wall containing the vacuum that preserves the liquid nitrogen refrigerant within the tank. Commonly, each canister is designed to hold 9 canes. Each cane holds an upper and a lower goblet, with a total of up to ten 0.5-ml straws per cane. To access straws of semen, the insulating neck plug is removed from the tank, and a canister is lifted about 1 inch and rotated 180 degrees so that the canister is located centrally and may be lifted to visualize the top of the straws. The tanks in the image can maintain liquid nitrogen (-196 degrees C) for 3 to 6 months before the refrigerant must be replenished. To ensure the tank is at least 20% full, the amount of liquid nitrogen remaining is monitored by inserting and withdrawing a ruler, with the frost line revealing the level of refrigerant. The bull's identity is on the top of the cane as well as on each straw. The technician grasps one straw with a forceps while the straw is still located within the neck of the tank, and removes the straw to be thawed. When an upper goblet is emptied of straws, it may be removed to access the lower goblet as shown in images. When one is finished working with the tank, the canister is lowered and rotated 180 degrees, the insulating neck plug is replaced, and the tank lid is closed.](https://s3.amazonaws.com/asasimagegallery-live/Thumbnails/1300.jpg "Handling frozen semen")
Handling frozen semen
Credit: Select Sires
Digital Credit: Select Sires
Publisher: None
Rights: Name must appear as a credit whenever the image is used -
Description: Liquid nitrogen vacuum tanks such as these were created (see NAL #631) to transport frozen bull semen from the sites where it is produced to the farms where it is used, and to store the semen on farms. [In the interest of clarity, one cane was raised to reveal the straws containing semen. However, in practice the straws should be raised above the lid of the tank only in the process of thawing the semen or for rapid transfer to another tank. The temperature of frozen semen rises rapidly when the straws are held even briefly above the lid of the tank, causing irreversible damage to the sperm when the temperature falls as the straws are returned to the tank.] A cross section of a typical tank reveals an insulated double wall containing the vacuum that preserves the liquid nitrogen refrigerant within the tank. Commonly, each canister is designed to hold 9 canes. Each cane holds an upper and a lower goblet, with a total of up to ten 0.5-ml straws per cane. To access straws of semen, the insulating neck plug is removed from the tank, and a canister is lifted about 1 inch and rotated 180 degrees so that the canister is located centrally and may be lifted to visualize the top of the straws. The tanks in the image can maintain liquid nitrogen (-196 degrees C) for 3 to 6 months before the refrigerant must be replenished. To ensure the tank is at least 20% full, the amount of liquid nitrogen remaining is monitored by inserting and withdrawing a ruler, with the frost line revealing the level of refrigerant. The bull's identity is on the top of the cane as well as on each straw. The technician grasps one straw with a forceps while the straw is still located within the neck of the tank, and removes the straw to be thawed. When an upper goblet is emptied of straws, it may be removed to access the lower goblet as shown in images. When one is finished working with the tank, the canister is lowered and rotated 180 degrees, the insulating neck plug is replaced, and the tank lid is closed.
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