Semen Freezing

Semen Freezing

                          
The first recorded scientific research into artificial insemination of domestic animals was conducted by Abbe Spallanzani in 1780 on a dog which resulted in a litter of puppies.(1) The use of artificial breeding has achieved tremendous progress since it's introduction to Australia in the early 1950's. 

Species in which artificial insemination is now routinely used include cattle, buffaloes, horses, donkeys, sheep, goats, pigs, poultry, dogs and honeybees. 

Prior to 1953, artificial breeding was performed using either freshly collected semen which had to be used immediately, or chilled semen which was diluted in special extenders and had a usable life of up to four days. 

During 1953, methods for the successful deep freezing of bovine semen were developed almost simultaneously in Britain and in Australia. 
Deep frozen semen can be stored for long  periods of time, so it is always available  when required for artificial breeding.
Another important advantage is that progeny can still be produced from a sire that is deceased or injured making him incapable of natural service. 

Artificial breeding has been routinely used in Australia since 1955. Initial research was carried out using liquid semen.
The first attempts at deep freezing of bovine semen were performed utilizing dry ice and alcohol at minus 79 degrees Celcius as the refrigerant. Individual doses of semen  were  frozen in glass ampoules. Canine semen was frozen as pellets on blocks of dry ice and stored in plastic vials.

In 1969 trials commenced using the Cassou (French) 0.5 ml straws for packaging semen. This system was adopted in 1970. The motive for this change was the increased storage capacity generated. 
Semen packaged in glass ampoules was not very efficient in terms of storage space required and the handling of ampoules was awkward. Straws are easy to handle. Straws can be filled and sealed automatically on a machine developed in France. These machines use ultrasonic sound waves to seal the straws. Ultrasonic sealing produces a cold weld so semen is not damaged by temperature changes. Identification of straws with the animals name and other information on a special printing machine with an indelible ink is quick and easy. Inseminations using straws are easier than with other types of packaging systems. Once frozen, straws can not be tampered with. This is not the case with pellets in vials.

Subsequent to successful trials in the  United Kingdom  using 0.25 ml "mini"  straws, also developed by Cassou, the Australian Association of Animal Breeders recommended that all Australian semen production centres convert to that packaging system. This further increased storage efficiency. There has been no good objective data that there is any difference in pregnancy rates from the various packaging systems, the freezing package seems to br of little importance.(2)

Just Genes Artificial Breeding Services uses 0.5 mL and 0.25 mL straws exclusively.

(1) Reproduction in the dog. A. E. Harrop M.R.C.V.S. Director of Canine Health Centre, Kennett, Newmarket, United Kingdom
(2) Advice for recipients of canine frozen semen 2013 Philip Thomas BVSc PhD FACVSc Dip ACT Queensland Veterinary Specialists, Stafford Heights,     Brisbane, Australia