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Advantages to Using Artificial Insemination in Swine Breeding Programs

Livestock Update, September 1999

Mark Estienne, Swine Research Physiologist, Tidewater AREC

During the past decade there has been a tremendous increase in the use of artificial insemination (AI) by commercial swine producers in the United States. In 1990, less than 7% of sows and gilts were bred by AI (Safranski, 1997). In contrast, a recent study of the structure of the Pork Industry revealed that nearly 50% of the nations sow herd was bred via AI in 1997 (PORK'98 Staff, 1998). The use of AI will continue to increase and within the next decade, nearly all swine producers will employ this technology.

Producers utilizing AI can obtain semen in several ways: 1) Semen can be collected from boars housed on the farm or at farm-owned, off-site studs. 2) Semen can be obtained from studs that are structured so that the individual producer retains ownership of his boars. For a fee, the stud provides "room and board" for the boars as well as semen collection and processing services. 3) Some producers have joined together to create cooperative boar studs from which they obtain semen. 4) Semen can be purchased from commercial studs, the majority of which are located in the Midwest.

With regard to obtaining semen from distant locations, overnight delivery companies such as UPS facilitate the use of AI for "mating" animals housed at widely separated locations.

The method of obtaining semen a producer chooses depends on several factors including available labor, technical skills and facilities. Each method has advantages and disadvantages. For example, on-farm semen collection and processing allow a producer a readily available supply of fresh semen and complete control of genetic and semen quality decisions. However, specialized labor and equipment is necessary for semen collection and processing and capital is invested in boars. Obtaining semen from off-farm sources negates the need for the aforementioned equipment and labor. There is a potential, however, for semen delivery problems and the producer is at the mercy of someone else for many genetic and semen quality decisions. Dr. Don Levis at the University of Nebraska has developed computer spreadsheets, available on the Internet at, to help determine which method is most cost-effective for a particular producer's situation.

Most semen utilized in AI programs is in a liquid (fresh) form and is utilized within several days after collection. It has been well-demonstrated that farrowing rates and litter sizes achieved using liquid semen can be equal to or better than those resulting from natural mating systems (Flowers and Alhusen, 1992). Frozen semen, which can be stored almost indefinitely, is available from some commercial studs. Use of frozen semen, however, results in lower farrowing rates and smaller litter sizes when compared to those achieved using natural service or AI with fresh semen.

AI offers producers numerous benefits. By allowing more extensive use of superior sires, AI can enhance the rate of genetic improvement and in terminal mating systems, increase the consistency of market hogs produced. The increased use of a genetically superior boar can be illustrated in an example. Semen could be collected from a boar 2 to 3 times a week without adversely affecting semen volume or sperm concentration. A typical ejaculate could be diluted with extender in such a manner as to provide 12 insemination doses. Assuming the boar works 52 weeks a year, and sows are bred twice while in estrus, the boar could "service" 624 females in a single year (2 collections per week x 12 doses of semen per collection x 52 weeks per year divided by 2 doses of semen per sow in estrus). The same boar used for natural mating could never service that number of females in one year.

That AI decreases the number of boars needed by a farmer is an economic benefit because fewer boars mean less feed and maintenance costs. Moreover, higher prices for particularly good sires can be justified because fewer boars are needed. Again, an example is in order. With handmating, a sow-to-boar ratio of 16:1 is fairly typical. Thus, for a 300-sow unit, 19 boars would be required. With an on-farm AI program, the sow-to-boar ratio is increased to 100:1 and only 3 boars are required. Assuming boar feed and maintenance costs of $1.00 per boar per day, the savings accrued by using AI in this example amounts to $16 per day or $5,840 dollars per year. Additionally, if the producer could spend $10,000 for boars, using AI he could buy 3 high-quality boars at $3,333 a piece. Using natural mating, the producer could be forced to purchase 19 mediocre boars at $500 a head.

If a producer adopts an AI program for which semen is obtained from off-site sources, the only boars that must be housed on the farm are those used for estrus detection. Additionally, one or more boars are usually kept for "emergency" matings in case there is a problem with semen delivery.

When obtaining semen (as opposed to boars) from outside sources there is a decreased risk of introducing diseases. Some diseases (e.g., Porcine Reproductive and Respiratory Syndrome [PRRS]) can be transmitted via animal to animal contact as well as AI. Other diseases (e.g., pseudorabies), however, cannot be transmitted through semen. Boars housed at studs are tested for, and vaccinated against, a variety of common swine diseases. Moreover, semen is collected under very sanitary conditions.

Another advantage of AI is that it allows the mating of animals of different sizes. For example, older, larger boars can be "mated" to smaller gilts when employing AI.

A final advantage of AI is that compared to hand-mating systems, it can be a time saver. Flowers and Alhusen (1992) indicated that any time more than four animals were bred in a day, the amount of labor required to supervise matings was significantly less with AI than for natural service. Additionally, as the number of matings per day increased, so did the relative labor advantage of AI over natural service. In that study, estimates of labor requirements for AI included collection and processing of semen, cleaning equipment, etc. Obviously, the amount of labor required for an AI program in which semen is purchased, rather than collected on the farm, is even less.

Two final comments should be made regarding AI. First, it certainly is not a requirement that breeding programs be exclusively natural or all AI. In fact, many producers effectively use a combination of natural mating and AI. For example, producers may use natural mating for the first service of a sow in estrus. Second and possibly third matings are then accomplished via AI. This system also works well as a "transition" system for producers gradually moving from all natural to all AI breeding programs.

Secondly, AI is a reproductive technology that can work for all producers regardless of the size of their operations. What all producers have in common, is that to capture the benefits of AI described above, they must make a commitment to learn the techniques and once employing AI, pay close attention to details.

If you would like to discuss AI in swine, please call me at (757) 657-6450, ext. 114.


Flowers, W.L., and H.D. Alhusen. 1992. Reproductive performance and estimates of labor requirements associated with combinations of artificial insemination and natural service in swine. J. Anim. Sci. 70:615.

PORK'98 Staff. 1998. Artificial Insemination use explodes. Pork'98<,i> 18(9):52.

Safranski, T.J. 1997. Artificial insemination in swine: A tool whose time has come. University of Missouri - Columbia, Animal Sciences Departmental Report. p. 10.

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