Despite some good results developing gender-specific proteins, the Danish Agriculture & Food Council (Videncenter for Svineproduktion, VSP), has stopped a high profile experiment related to gender-selected semen.
Together with the Welsh company Ovasort, VSP has worked on a project aimed at developing a method to separate boar sperm cells in order to produce more female pigs. Although progress was made in the research, the eventual goal of producing more female piglets was not met.
In current practice, entire male piglets have a risk of developing boar taint, which is unwanted. The common solution of castrating them will be voluntarily banned in the European Union as from 2018. The VSP therefore set out to find solutions to avoid castration.
No usable gender-specific proteins
The hypothesis of the project was that the sperm cells on their surface have some gender-specific (not previously identified) proteins and that these proteins could be used to separate the two types of cells. This way, the idea was to achieve a higher rate of female pigs, at the expense of male pigs.
During the project, several of these proteins were identified, which was more than expected. In addition, antibodies against two gender-specific proteins were developed. On top of that, tests were conducted, showing that these antibodies can bind to sperm cells and cause them to clump together. Lastly, it was shown that antibody-treated sperm cells are fertile with high litter sizes as a consequence, showing that sperm cells were not damaged by the treatment.
Unfortunately, the sex ratio in the tested litters was the same as in ‘normal’ litters. So it was not possible to produce more female piglets.
Originally it was expected that the sex-linked proteins were quite specific for Y- and X-cells respectively. This would constitute a simple background to develop 100% specific antibodies that could be used to kill Y-cells, for example by combining antibodies with a killer molecule that destroys the cell membrane of the Y-cells.
Unfortunately, it appeared that the detected proteins were found in both Y- and X-cells (but in different amounts). Other more technically difficult separation methods were considered, but the success rate was assessed to be too low in relation to efficiency.
Yes to breeding against boar taint
VSP’s activities related to boar taint will now focus on breeding against boar taint. Recently the VSP started a new three-year project in collaboration with the University of Copenhagen. The project is partly funded by the Danish State.
In 2010, VSP also denounced the idea of using chicory in the feed as a means to solve problems with boar taint in the meat. This happened in 2010.
**Also read Pig Progress article: Castration comes to a standstill in the EU