Concentration inside your blisters : Which methods of homogenization to choose ?
Extender quality, control of the production parameters, good laboratory practices are beyond the numerous factors that can influence the homogeneity of your boars’ semen. Beyond those there is one simple thing we must also consider. For time saving reasons, simply ignoring or carelessness, laboratory technicians, operators do not always mix the semen before filling the blisters or sampling to analyze the concentration for instance. This harmless practice, which takes a few seconds, can have a significant impact on the concentration and regularity of your semen doses. If you don’t proceed to homogenization, by hand or with a magnetic stirrer, you might be surprised with the results!
How important is the semen’s homogenization ? Which method should be used ? How fast does a boar semen sediment ?
Speed of sedimentation : how fast a sperm will sediment ?
Boar stud technicians observe sometimes a variation of the concentration in the diluted semen which can be doubled within the same ejaculate.
The first thing to know is quite logical. Spermatozoa are heavier than the environment in which they swim. They will naturally settle to the bottom of the container because of gravity.
As shown in graph n°1, after less than 60 minutes, more than half of the sperms present on the container will go down and settle to the bottom of the bucket. The number of sperms will continue to concentrate in the bottom during the next hours.
Which method to homogenize my semen ?
Regular concentration of sperms in each dose produced all along the filling process is a clear target for better production quality. It becomes essential to homogenize the semen before packing it to avoid any big difference in terms of concentration.
But how do you properly homogenize ? We could think a magnetic stirrer would be the most effective solution, but this might be too time consuming and may represent a potential risk of contamination if the magnetic stirrer is not properly cleaned between two ejaculates. We did analysis by comparing different methods. As shown on the graph n°2, we estimated the concentration on many blisters based on 4 different methods of homogenization process :
- 0 = Immediate : packaging direct after dilution of the ejaculate
- 1 = Sedimentation 1 hour and packaging without homogenization
- 2 = sedimentation 1 hour and packaging after 5 round of pipe
- 3 = Sedimentation 1 hour and packaging after magnetic homogenization.
Graph n°2 shows there is an important variation of the concentration in treatment n°1 : the concentration of the semen doses was between 3 billion and 1.8 billion which is a much too high variation. The peak for the last blister comes from the fact that the sperm have sedimented in the bottom of the semen bag, so logically be more concentrated for the last blister packaged. For the treatments 0,2 and 3 we can see that as long as the semen was not stabilized or was mixed before packing, the concentration stays between 2 and 2.5 billion of sperms. This will not impact the insemination. To be noticed : there is no significant difference between homogenization with a pipe or with a magnetic stirrer. Moreover a not well cleaned magnet could be another source of contamination. This study shows that there is no significant difference between those 4 methods. But, there is an important heterogeneity between the 4.
This very simple test confirms the importance of homogenization. It must absolutely be done for the semen that had a period, even a few minutes, of sedimentation. That will not take too much time and will have a significant impact on your customers / your insemination results.
Don’t forget to always mix your semen before packing it !
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