I've been getting a LOT of questions recently about semen quality from particular boar studs and semen-quality issues in general. I hope I've been able to answer everyone's concerns. In light of this, I wanted to post this mini-essay which should answer most questions about semen quality and help you work together with the boar studs to get your sows settled. Feel free to post your comments in the comments section at the bottom!
Choosing a Semen Provider
In the interest of choosing a semen provider that will give you the best opportunity to settle your sows with a large litter of healthy pigs, and to protect your farm from the introduction of new diseases, the following questions and discussion should provide the semen customer with some information to help make a good decision.
A primary concern when purchasing semen should be safeguarding against the introduction of new diseases, namely PRRS. Without going into a detailed description of the disease, it is safe to say that PRRS can be devastating to your herd, and that PRRS virus is commonly SPREAD THROUGH SEMEN. Boar studs need to take detailed precautionary measures to ensure they are selling a PRRS-free product. When boars are purchased at shows and even privately from some farms, most of them are going to test positive for PRRS virus. These boars need to be isolated on a separate farm from the main stud, and workers cannot be allowed to enter the main facility within 24 hours of contact with the isolation facility and only after a shower and change of clothing. These are bare minimum standards. Many bio-security protocols would insist on 72 hours or more down-time between isolation facilities and the main farm. Boars need to test negative using Elisa test on a blood sample and maintain that status for a second test before entering the main facility. The main facility should be regularly tested also (at least quarterly if not monthly) to ensure that the boars are all negative for PRRS and not shedding virus.
Many showpig studs will collect PRRS-positive boars in the isolation barn and sell that semen to their customers. This is very risky. The only way to do this is to have the semen PCR tested for PRRS virus before shipping it to the customer. Even this test has been proven to be only slightly effective at best. It can often take a very long time for a boar to “turn negative” for PRRS in isolation, particularly if there continue to be new positive boars introduced to the same isolation facility. Some boars never turn negative. The stud owners have a lot of money invested in these boars and need to sell semen to generate revenue. They cannot usually wait for a new boar to show a negative Elisa blood test before selling semen. If they do not PCR test the semen for PRRS virus, it is very likely that they will spread PRRS to your farm through the semen you purchase.
Additionally, many boar studs have their “isolation facilities” in the same location as the main stud, just in a different building. This is simply not acceptable. PRRS virus travels easily by air, rodents, mosquitoes, etc… There needs to be a few miles distance between the isolation facility and the main facility (or any other pigs for that matter). Also, many boar studs are actually set up on a showpig-producing farm that has active PRRS virus. Even those that are well-isolated often times have employees who are operating a pig farm at home. Those employees seldom have sufficient down-time between home and work to provide a true barrier against PRRS infection. At the very least, they need to shower and change clothing before entering the facility.
How to protect your farm. What questions to ask?
1. Please explain to me your bio-security protocol. Are employees allowed to own pigs at home? Are they required to shower and change before entering the stud?
2. When you purchase new boars, where are they housed? Are they on the same site as the main stud? Are they tested for PRRS? Do any boars ever enter the site of the main facility without having tested negative for PRRS?
3. The boar that I am interested in purchasing semen from….has he passed a PRRS Elisa test? If he has not, have you PCR tested the semen that I will be receiving? Please send a copy of the PCR test results with the semen! If not, how can I be sure that the semen does not contain PRRS virus?
4. Are there other hogs (sows, gilts, growing pigs) on the same site as the boar stud? Have they all tested negative for PRRS?
Good semen quality has many dependent factors, and each one of them needs to be properly addressed to ensure that you receive good, fertile semen with a decent shelf-life. Let’s start with the boar and go from there.
The critical points to address here are cleanliness and temperature. There are other issues such as lighting, space allowance, diet, boar handling procedures, and more that will also play a role in quality sperm cell production, but if we can address the two most critical points, our odds of success increase dramatically.
Boars should be housed in a clean, dry building with good ventilation. They should not be lying in mud, urine, manure, etc. They need to be clean and dry when they are collected to reduce the likelihood of excess bacteria entering the semen collection vessel from manure, dirt, straw, shavings or urine on their sides and belly. They should be in a temperature-controlled environment. Specifically, there should be evaporative cooling or an equivalent and possibly a dripper system (depending on climate) to ensure the building and boars can be kept cool during the summer. Just having ventilation fans is usually inadequate. Boars housed in hot climates should have both evaporative cooling as well as a dripper system that drips on the boar’s rump and cools his testicles. When temperatures reach the upper eighties, most boars begin to lose fertile sperm cell production for a period lasting several weeks after the heat stress occurred. Ideally, the boar’s environment should be in the upper sixties or low seventies year-round.
Collection and Lab Procedures
There are a multitude of factors to consider in the collection and processing of semen, and each one of them can play a pivotal role in the quality of your semen dose. We will address here only the most critical points.
The major enemies to long-lasting fertile semen doses include sperm cell count, extender used, bacteria load, and proper motility and morphology assessment (the lab technician’s assessment of the percentage of live, fertile cells in the ejaculate).
Sperm cell count
The boar stud lab needs to use an accurate method of counting the total sperm cells in the ejaculate. The best available is a CASA system (computer aided semen analysis) which not only calculates sperm cell concentration but also identifies abnormal or dead cells. Very few studs (perhaps none in the showpig world) use this system as it is very expensive. More common is use of a Spermacue. This is a relatively accurate device (if it is properly calibrated) that is simple to use. Other machines exist that can be accurate, but allow more room for human error such as spectrophotometers that utilize a measured amount of semen and diluents to calculate the number of cells. Any of these are acceptable methods. More accurate but time consuming is using a hemocytometer to count cells under a microscope. A SimpleCount Sperm Kit provides and the accuracy of the hemocytometer with much more speed and ease of use at an economical cost. What is NOT acceptable is a guess based on volume of the ejaculate, color of the semen, or simply the number of doses needed that day.
A semen dose should contain a minimum of 2-3 billion motile, normal sperm cells. This is excluding cells with abnormalities, dead cells, etc. Concentrations up to 4.5 – 6 billion are usually acceptable, but if you begin to exceed 6 billion cells longevity can be sacrificed.
Boar studs have a variety of extenders to choose from. Short-term, mid-term and long-term extenders all vary in composition, price, sperm cell longevity, and the way sperm cells behave when viewed at storage temperatures. Semen that is collected on-farm and used within the same production system is often times extended with a low-cost, short-term extender (2-3 days longevity). However, any dose of semen being sold to another producer should always be extended using the best-quality long-term extenders available because the stud owner doesn’t have any control over how many days the customer will store the semen. Even with the best long-term extenders, with a properly-processed semen dose, the average maximum shelf-life of boar semen will be 7-8 days. Positive results with older semen are obtainable, but should not be expected. Many boar ejaculates will not be fertile at 7 days of age either. It is always best to use the semen as quickly as possible to ensure fertility. Do not automatically assume that it will still be fertile at 7-8 days of age.
The best long-term extenders are FertiMaxx and Gedil. Modena is commonly used in many showpig studs and is mistakenly believed to be equal to the other extenders. The reason that it is popular with the showpig studs is because it will show good motility (sperm cells will move normally) at storage temperatures without warming it to body temperature. Remember that the better long-term extenders cause the sperm cell to slow or even stop moving when stored at 16-17 degrees C. Samples need to be thoroughly warmed before analysis. Often times, customers will call the boar stud complaining that the semen is dead because they failed to warm it properly before looking at it under the microscope. By using Modena, studs can avoid these phone calls. The problem is that Modena will not keep semen alive as long as the other recommended extenders. It is a mid-term extender. Studs should be encouraged to switch to a better long-term extender. If you plan to use semen extended with Modena, be sure that you will be able to use the semen by the time it reaches 4 days of age to ensure the best possibility of success.
Collection Timing and Frequency
An issue for many showpig studs is the timing and frequency of collection. Normal collection days are Monday and Thursday, with semen being sent by UPS the same day. Some studs, however, prefer to collect the semen the afternoon before (Sun. or Wed.) and ship out the following day. In those cases, depending on what time of day your semen arrives, it may already be 48 hours old when you receive it. If the semen was not extended with a good long-term extender, you may have only 2 days left before fertility drops significantly.
Ideal collection frequency for boars is one collection every five days. A boar needs to be collected a minimum of once every ten days for optimal semen quality. When boars are collected too frequently, they ejaculate a very high percentage of immature cells and their sperm cell count in general decreases. Those immature cells will not fertilize an egg. Many times, because semen demand for a particular boar is high, a stud will collect a boar more frequently to meet the demand. In those cases it is very likely that the semen doses being sold contain very few mature cells that can fertilize an egg. Your odds of success are minimal. It is acceptable for studs to collect boars every Monday and Thursday during high-demand season, provided they are producing mature cells. It’s more reasonable to expect success with twice-per-week collection from mature boars than from new, younger boars. Some boars can only be successfully collected once per week.
Bacteria in the semen dose will greatly reduce the shelf-life of the sperm cells. As you probably know, bacteria are present everywhere in the boar environment and can be found in many places in the lab as well. It is critical that the boar stud does a thorough job of cleaning the lab, keeping boars clean, and properly collecting boars to keep contamination minimal. This is where many studs “drop the ball”. While the extenders contain antibiotics to limit the growth of bacteria in the semen dose, if the bacteria load is too high, the antibiotics are insufficient to stop the multiplying bacteria from producing toxins that kill the sperm cells. The source of the bacteria can be the barn, the boar, the lab, or even the water that is being used for the extender.
Motility and Morphology Assessment
The boar stud needs to perform an accurate assessment of the quality of the sperm cells in the ejaculate. They need to be able to accurately estimate the percentage of live, motile, normal cells. This requires a lot of training and a lot of experience. This is not an exact science, but there are minimum standards that need to be met before an ejaculate should be sold. Often times, if there appears to be a high percentage of abnormal or dead cells, studs believe that they can get by simply putting a higher number of total cells per dose. Research has shown that this seldom results in a fertile dose of semen. A semen dose should meet an absolute minimum standard of 70% live, motile, normal cells with at least 2-3 billion of these cells per dose. Anything less should go down the sink drain rather than into a semen bottle.
Some studs may have improperly trained or inexperienced people performing this task. Often times, semen is sold to the customer in the hope that it is “good enough”.
Top-notch commercial studs send samples of semen weekly to a third-party lab for analysis. These professional services provide detailed information about the semen dose, including accurate sperm cell count, detailed morphological analysis (a count and description of abnormal sperm cells), detailed bacteriology including bacteria count and type, motility assessment, and information about the consistency of the semen doses (range of cell counts, etc..). This information allows the stud to compare their analysis to the most accurate analysis available and gauge their performance. EVERY SHOWPIG STUD SHOULD BE UTILIZING THIS SERVICE. Given the investment being made by the average semen customer for showpig semen ($50 - $300 per dose), this kind of quality assurance is a must. Dr. Althouse in Pennsylvania is perhaps the most commonly used lab for this service, but there are other quality services available as well. Dr. Benny Mote at the University of Nebraska provides a valuable service with semen analysis for showpig boar studs as well.
There are many more factors involved in proper semen processing. In fact, all of the things listed here could be done properly and a mistake in extender/semen temperature could be made that would shock all the sperm cells and render the entire ejaculate useless. However, the odds are that if the boar stud is taking care of all these major points, you can feel a bit more secure that they are handling most of the other details as well. Studs should be working with a professional service to audit their performance and constantly seek out ways to improve.
Questions to ask.
1. Are your boars kept indoors or outside?
2. What is the normal temperature of your barn? More specifically, what is the temperature inside the barn on the day I am ordering semen? How hot does your barn get in August?
3. Do you use any type of cooling system in your barn? Drippers? Evaporative cooling?
4. Are your boar pens bedded or are the boars housed over slats? Are they in pens or stalls? If they are bedded, how often are they cleaned?
5. How many sperm cells are in a dose of semen from your stud? Is that the total cell count, or are you counting only the motile, normal cells?
6. What method do you use to calculate the sperm cell count? Spermacue? CASA system? Spectrophotometer? “Color method”?
7. What extender are you using?
8. What day do you collect? Is it the same day semen is shipped, or the day prior?
9. How often (with what frequency) do you collect your boars? Weekly? Twice per week? Daily?
10. Please describe your collection procedure. Is the boar’s sheath drained of all fluid prior to collection? Is the sheath hair trimmed? Are the sides and belly of the boar clean and dry? Are the dummy-sow and collection pen clean?
11. What are your standard criteria used to pass/fail an ejaculate? What percentage of motile, normal cells do you require as a minimum? What method do you use to determine this?
12. Are you using the service of a third-party lab to analyze your semen doses? If so, which one? Have they found bacteria in the semen? If so, what steps have been taken to prevent future contamination? How have their motility, morphology, and cell count analysis compared to your own?
The point of this minor essay is not to cause problems for the boar studs or to create a disagreement between you and your semen provider. The point is to raise the quality standard of the semen providers and improve your odds of success. While it may be uncomfortable for you to ask many of the questions, especially if you have already established a relationship with the semen provider, they should not be offended by your inquiries. A professional business values an educated customer. If they are uncomfortable answering your simple requests for information, ask yourself “why”? A good business will earn your trust and respect by providing you with all the information you need to make a good decision. Those that prefer to sell you semen without having to provide much information about their procedures probably need some improvement in those areas. Encourage them to seek out a professional and get some help to make the necessary improvements to their operation. In the end, do you want to spend $100 - $600 to inseminate your sow, all the while hoping that the semen was good?
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