Fifty years ago artificial insemination in pigs was practically unknown, but today in many European countries AI accounts for more than 90 percent of matings. Ironically,
As in the
1) On-farm AI: This system, also known as do-it-yourself AI, is not the preferred option but is popular in some countries (such as
2) Commercial boar studs: In countries such as the
So, let’s start by looking at some of the recent developments in boar management.
Housing and environment: The latest trend is to house boars in deep sawdust instead of on solid floors or on other flooring types. Deep sawdust keeps the boars clean and dry, and enhances feet and leg soundness. The sawdust is changed once or twice a year. Boars do need to be wormed before entry and checked regularly for parasites.
Welfare: Current European legislation prescribes a living area of at least 6 square meters per boar, with some welfare groups recommending 7.5 square meters.
Health: There are two ways to look at disease-introduction risk. On one hand, there are fewer diseases that can be spread via semen compared to diseases potentially spread by live animals. On the other hand, semen introduction is frequent (usually at least once a week) on a farm, so that increases the risk.
The impact of a disease break in a boar stud could be widespread, as many farms could be affected. For example, a 250-head boar stud would supply semen for approximately 75,000 sows. That makes health-risk checks extremely important.
Polymerase chain reaction: These tests have improved in recent years.
PCRtests can be used on semen, serum or both. They are mainly used to monitor semen for the presence of PRRS virus. The RT-nested PCRs are the tests with the highest sensitivity.
Semen and blood sampling: The advantage to semen testing is that the boars do not need to be restrained for sampling; the disadvantage is that results might not be available before the semen is used.
Because most viruses appear in blood before they appear in semen, new blood sampling techniques are becoming more common. Blood samples are obtained from veins while the boar mounts the breeding dummy. Blood testing can be very useful, especially when monitoring PRRS-negative studs for recent infection.
Semen washing: This is a relatively new technique that is not yet ready for commercial use. However, an adapted version has proven to eliminate PRRS virus from semen.
A recent study was conducted to see if washing would affect semen quality and farm performance using PRRS-negative washed semen. Seventy-five inseminations were carried out using washed semen versus 47 using normally processed semen. For both groups the farrowing rate exceeded 95 percent, and litter size was more than 12 pigs. In the end, any differences were statistically insignificant.
Semen collection and equipment: During the last six years automatic semen collection machines have surfaced (such as Gene Diffusion’s Collectis). An electro-pneumatic regulation unit allows semen collection to occur mechanically. Within this process one employee can supervise up to three collection units, which is naturally a big labor savings.
Of course, there also are semi-automatic collection units (such as Minitub’s Automate) on the market.
Now let’s look at semen processing, which involves several options and levels.
Concentration: Developments here include the NucleoCounter, produced by ChemoMetec A/S. This system uses fluorescent stains to count seminal
DNA. While it is accurate, simple, precise and fast, this technology is still relatively expensive for small boar studs.
Quality-control programs: Centers generally have their own standards and programs. However, in the
, following industry concerns about semen quality, the British Pig Executive met with all AI centers to establish uniform quality standards, which BPEX independently monitors. United Kingdom
Fresh-semen extenders: There are “short,” up to three days; “medium,” up to five or six days; and “long,” up to eight, nine or even 10 days.
Long-term extenders have improved and have the benefit that
PCRresults can be available before the semen is shipped, but they are expensive and there’s still a perception that “fresher” semen is better.
Semen containers: Semen is usually packed in bags, tubes or flat packs that are flexible and can be color coded.
The Gedis is a 6-inch-long catheter that contains the semen. The catheter is inserted through the vulva, and the sow absorbs the semen without human aid.
A French company, Cobiporc, has just launched its Neosem system, which holds semen under pressure in a container about the size of a golf ball. When the container is attached to the catheter the semen flows quickly into the sow.
Semen techniques: In recent years intrauterine insemination techniques have been developed, which allow boar semen to be deposited in the uterine body or the uterine horn.
With the process called IUBI (in the uterine body), semen is deposited in the uterine body, about 8 inches further than with the cervical method. A double catheter is needed for insemination. Some studies show that the sperm concentration could be reduced by two-thirds without affecting farrowing rates or litter size. Other studies, though, found that with IUBI, litter size was significantly lower.
With the uterine horn or deep intrauterine insemination (DIUI), a flexible catheter 70 inches long and ¼ inch in diameter is inserted into the middle of one uterine horn to deposit semen. This technique requires a great deal of skill and requires specialized application with frozen/thawed semen or sexed semen.
Frozen/thawed semen: This option is ideal where pig units are located in remote areas. Disease-wise, it allows semen to be tested for pathogens before it’s dispatched for use. It also allows rare breeds to be preserved. Unfortunately, it is expensive, and science still has not found successful thawing methods. So, litter numbers fall short of those for fresh semen.
Editor’s note: This article is adapted from a paper presented at the 2007 International Pig Science Conference held at the University of Nottingham, UK, by Meritxell Donadeu of