Veterinary Andrology and Reproductive Techniques

PELLET METHOD

Pellet method was developed by Nagase and Niwa (1963) in Japan.

• Here the semen is rapidly frozen as small pellets on solid carbondioxide following dilution with media containing carbohydrate and glycerol.

Freezing method

The volume of semen pellet is 0.1-0.2 ml. The freezing is done with the help of solid carbondioxide.

• The media used for pellet method is as follow

S.No.	Components	Quantity
1	Lactose	75.30 ml
2	Glycerol	4.7 ml
3	Egg yolk	20 ml

• Antibiotics as per the schedule
• The semen is diluted with the above diluents in a glass tube.
• It is placed in 250 ml beaker having water at 30⁰C.
• The beaker along with the semen is placed in a refrigerator/cold handling cabinet at 5⁰C for 5 hours.
• 0.1-0.2 ml of semen is taken in a calibrated pipette and is dropped on solid carbondioxide.
• To facilitate this, the solid carbondioxide was smoothened to a flat surface with an electric sander and small depressions were made by the use of metal die.
• The depressions were approximately 2mm in diameter and 1 mm in deep.
• The semen is allowed for 10 minutes for freezing on the solid carbondioxide.
• Then they are collected by using pre cooled forceps in to a goblet and stored in liquid nitrogen.

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Thawing

• The pellet is thawed by placing it in 1 ml 3% sodium citrate solution containing 1.5% fructose at 20⁰C.
• The dilute semen is taken in glass catheter and inseminated.

Advantages

• Economical method
• Requires less storage space

Disadvantage

• As the pellets are stored directly identification is difficult
• As the pellet is placed directly in to liquid nitrogen the chance of contamination with organisms in liquid nitrogen is more
• When the pellets are taken with forceps for storing and during thawing they may break and gets attached to forceps or may fall anywhere. This leads to loss of sperms.
• The freezability of sperms by this method is moderate.
• The thawing is a tedious process when compared to other methods.
• The insemination is done with glass catheters which is having disadvantages

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