sexed semen in focus - introduction to x-vik and y-vik

Without any doubt, sexed semen has revolutionized cattle breeding and modern herd management. Here is a short introduction to the production of sexed semen at VikingGenetics.

Principles behind sexed semen

Technology makes it possible to sort semen with X- or Y-chromosomes. What is a chromosome? Chromosome is a structure that is found in all cells, and chromosomes carry the genes. Chromosome means ‘colored body’ that is because they could be colored. For mammals, females have two X-chromosomes while males have one X-chromosome and one Y-chromosome. 

How can we see difference between X and Y – semen cells? - We color the semen cells with fluorescent colorant named ”Hoechst 3332”. When the cells are exposed for UV light, the color in the cells emits blue light. X sperm cells emit a more intense fluorescent light than Y sperm cells as X-cells contain 3-4% more DNA than Y-cells. 

How is the production process organized at VikingGenetics?
Step 1: Receiving and controlling fresh semen 

When we receive fresh semen, we have some requirements that must be fulfilled to ensure the optimal sorting process. 

We measure concentration and vitality using flowcytometry, while motility and normal morphology is measured using IVOS.
Step 2: Optimization and Coloring

The next step is adjusting the concentration to the most optimal for semen survivability adding a reagent. After that semen is centrifuged, and the desirable concentration is achieved. 

Coloring of semen happens over water bath (temperature 35°C), we also add reagent that contains nutrition for cells and red fruit color. This red color penetrates cells with broken membranes. These cells won’t emit the blue light and they can be sorted away as "dead cells". When the sample comes out of the water bath, another reagent is added which provides extra nutrients to the sperm cells.
Step 3: Sorting

Semen is then placed in sorting equipment. All the magic happens in the nozzle, which key function is to center and orient the cells individually. The individual cell is illuminated with laser that makes the cells emit the blue light. The X sperm cells are led to the left by a positive charge and the Y sperm cells are led to the right by a negative charge, what is left ends up in "waste". The processed semen is then collected and cooled down to 4°C.
Step 4: Freezing and Quality Control

Sorted semen is then prepared for freezing. Semen is filled into straws, with each straw containing about 2 million sperm cells. Straws are frozen and packed in containers that are now ready to be distributed to the farms all over the world.
One important step is quality control that we perform for each freezing batch after 24 hours. The straws are thawed and measured for different parameters.
At our lab we produce both X-sorted semen (X-Vik) and Y-sorted semen (Y-Vik). Using X-Vik semen ensures you to get 90% heifer calves and in combination with the genomic test on females to pinpoint the top females in the herd, X-Vik semen is an important management tool to secure rapid genetic progress in your herd. Y-Vik introduced in 2010 is mostly used for beef semen and by using Y-Vik, you can be 85% sure to get a bull calf.

Earlier this year we celebrated 10 years of sexed semen production. Today we have 11 sorters in the semen sexing laboratory operated by 20 employees 24 hours five days a week. We rely on the latest technology and knowledge to ensure that we provide high-quality sexed semen solution for dairy and beef producers worldwide. We work continuously on optimizing and improving the procedures to minimize a fertility gap between sexed and conventional semen and improve our procedures to better utilize semen collected from young, genomic bulls.

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