Boar studs have a lot of pressure on them today in the production world. Sow farm breeders have complete faith in the tube of semen. Most sow farms do not check semen daily, but rather rely on the stud to monitor retained doses for any issues. Semen is delivered fresh with an expiration date. On-farm drop points and storage all have an impact on the doses, as well. So, studs must protect their customers, not only on the health front, but also viability of the semen through expiration, and you never know what may cause a negative impact.
Technology like Computer-Assisted Semen Analysis systems have become a standard in evaluating collections for motility, morphology and concentrations. Every collection must pass minimum values at the time of collection. Once doses are produced, sample doses are retained to be monitored through their expiration date. Graph 1 contains average motility for several genetic lines by day, post collection. All semen will decline over time as shown. The red line is the minimum cutoff at expiration.
The PRISM database by Minitube is a common system used to manage the data. These data are only beneficial if you monitor and report out issues. This is critical to the stud maintaining a quality product for customers. Viability of semen through expiration is the primary issue once semen leaves the stud.
If an issue arises, doses can be recalled and replaced to achieve better performance for the sow herd. The first line of defense is the lab worker reporting the doses falling out of the acceptable window. Then the hard work begins to quickly understand why.
A recent issue at a stud put the response system to work. What happened? One-day old semen was failing the storage check — a lot of dead semen.
The first step was to contact customers to stop the use of the semen; and let them know replacement doses would be set up for them. The next was to start digging in to identify the reason by working through the list of rule-outs.
- Technician error while conducting the analysis?
- Was semen good at collection?
- Storage conditions stable?
- Bacterial contamination, such as with Serratia, which is known to kill semen?
- Extender pH OK?
- Osmolarity of the extender — checks the correct dilution and mixing of extender?
In this case, the normal rule-outs did not yield anything that accounted for the bad semen. A third-party consultant was used to verify procedures and observations at the stud, as utilization of an expert consultant is critical when elevating any investigation into uncharted territory.
Since the semen appeared normal on initial examination, the issue seemed to arise from the extender, and clearly started on the day the affected doses were collected.
Looking further into possible extender issues, contact with the extender manufacturer did not yield answers, as other studs with the same extender lots had no problems. Special water is the other major input in semen dose production. This water is not straight from the rural water plant — it has been filtered and treated to be clean. The water is passed through a reverse-osmosis filtration system, then de-ionizing tanks, and finally is ultraviolet treated prior to going in to make extender.
Water samples (pictured below) were taken from the system. The top tube was taken after the DI tanks; the bottom was after the RO system, but before the DI tanks. Both tubes were shaken immediately prior to taking the picture.
Clearly, there is a difference between the tubes — bubbles are bad. What is causing the bubbles in the top sample? Regular quality control testing did not yield any insight, so we utilized liquid chromatography/mass spectrometry to identify what compounds were involved.
Polyethylene glycol and polypropylene glycol were two of the compounds identified. Both are common ingredients in cleaning products. Our problem was identified in the DI tanks. The dates of the last DI tank change coincided with the change in the semen.
Now the stud closely monitors all DI tank exchanges, and does in-house checks prior to using the treated water for doses to be shipped to customers. One of those checks is making up doses of water only, as seen in the picture above, and looking for bubbles. A simple test, but one that we have found to be extremely effective.
The liquid chromatography testing takes too long to be considered useful to practical quality control at the stud level. Fully extended doses are also made and monitored for viability verification.
Boar stud monitoring of retained doses is crucial to protection of production at customer herds. New challenges continue to pop up, so the stud staff must be on their toes to report abnormal findings. With every challenge comes an opportunity to add to our quality control program going forward. A key point to remember is semen is delivered fresh and is extremely sensitive. It all starts at the stud, but every producer must do their part as well to protect the semen for optimum success when put into a sow.