Aqua Gen has implemented new cutting edge technology for cryopreservation of milt, representing a milestone in Aqua Gen’s
selective breeding scheme. Through the subsidiary Cryogenetics the technology is also offered to others, in Norway and abroad.
Last spawning season milt was frozen for a Scottish aquaculture company and milt from wild salmon for VESO/The Directorate
for Nature Management (DN).
Several years ago Aqua Gen realized that use of frozen milt is a prerequisite for increased efficacy of the selective breeding
program. This year the four breeding populations have been merged into one by means of frozen semen, which also facilitates
improved exploitation of superior sires. Frozen sperm can also be an alternative to eyed eggs in the distribution of improved
genetics from Aqua Gen. Cryopreservation techniques up to now have not been good enough for large scale utilization. Therefore
Aqua Gen entered the Team Semin consortium, a research collaboration between 5 breeding organizations in Norway with main
focus on sperm preservation. A two year research project together with
GENO followed in 2002. The results from this project were so good that implementation of the new cryopreservation technology could
be implemented in 2004, for both Aqua Gen and external employers.
The so-called pellet method was one of the first methods employed for freezing fish sperm, by which milt was frozen on blocks
of dry ice. This method gives low and variable sperm quality and it is not suitable for large scale freezing. Later different
variants of polyethylene straws for freezing in nitrogen atmosphere have been developed. Neither this method is suitable for
freezing large quantities of milt.
The main elements in the new technology employed by Cryogenetics are:
-
Rolf Myklebustis preparing dilution of milt prior to freezing.
New packinging. We can freeze volumes of 5 ml in each pack; straw methods allow only 0.5 - 1 mL in each straw.
- Standardized doses based on sperm density measurements. (salmonid milt can contain 5 – 15 billion sperm/ml.) The milt is diluted
to obtain equal number of sperm in each dose/pack.
- New extender solution
- New freezing protocol
In the trials the fertilization rate was approximately the same as when using fresh semen (~ 90 %).
In order to commercialize the new technology the subsidiary Cryogenetics has been established, owned 50/50 by Aqua Gen and
GENO. Cryogenetics is responsible for freezing for Aqua Gen and other employers.
The spawning season 2004/2005 was the first operating season for Cryogenetics, and freezing has been carried out for three
operators:
-
Morten Jensen and Rolf Myklebustare filling storage tanks with liquid nitrogen (- 196 ºC. Here the milt can be stored for
decades (centuries?)
Aqua Gen. The last season was a milestone in Aqua Gen’s breeding work. The four original populations in the breeding nucleus, having
been run in parallel since the 1970’s, were merged into one. This endeavour had been impossible without the new milt cryopreservation
technology, which also is a prerequisite for creating production lines for commercial production of eyed eggs for the industry.
The results from the large scale freezing of milt turn out to be just as good as during the experimental studies, during which
we constructed a special department with small egg incubators – as many as 768 to be able to run all the experimental units
simultaneously.
-
The Directorate for Nature Management. Demonstration experiments have been carried for The Directorate for Nature Management. VESO is responsible for freezing milt
in connection with conservation of wild salmon strains in Norway, and the trial was carried out in co-operation with VESO.
Using Cryogenetics’ technology has the potential to make the enhancement work more cost-efficient. Experience from the trial
will decide if this will be the future cryopreservation technique for more effective conservation of salmon genes in Norwegian
rivers.
-
A Scottish aquaculture company. Cryogenetics was contacted by a Scottish aquaculture company running their own breeding program. They wanted to freeze milt
from valuable sires in their own breeding population. Fresh milt was transported to Trondheimin the beginning of January for
freezing and storage there until later return to Scotland.
The freezing of milt is carried out at Geno’s A.I. centre Hallsteingård in Trondheim, where there are good laboratory facilities
and a large storage room for semen. The manager of Cryogenetics is Rolf Myklebust.
|
| Lagerhall med fryst sæd fra storfe og laks |
|
| Verdifulle laksegener trygt bevart i flytende nitrogen |
|
| Bjørn Bjøru,VESO, foretar befruktninstest med melken som ble fryst ned av vill-laks. |
