Swine castration FAQs

Q. Why are male swine castrated?

Male pigs are normally castrated between 4 and 14 days old. Photo from the Animal Science Image Gallery

There are two reasons to castrate a male pig: behavior and meat quality.

Uncastrated male pigs, called boars, are known for aggression. Boars will bite, shove and jump on other pigs. Boars can also be hard for workers to handle, and boar aggression can be a risk to worker safety. Castrating a male pig will reduce these behaviors.

Some boars also produce “boar taint” or “off odors.” Boar taint does not affect food safety, but it does change how meat tastes and smells. Some describe it as a “musk” or a smell similar to onions or manure. The USDA Food Safety and Inspection Service does not allow meat with a boar taint smell to enter the human food supply.

Boar taint is associated with the hormones produced naturally in uncastrated male pigs. Scientists think the odor evolved to attract female pigs. Castrated male pigs, called barrows, do not have testicles, so they cannot produce these sex hormones.

Q. How are swine castrated?

The castration process has many steps and should only be done by a person with training and experience with pigs. Male pigs are castrated using a disinfected surgical knife. A trained worker or veterinarian holds the pig and makes an incision above each testicle. The testicle is pushed through the scrotal sac. The person doing the procedure is careful to break the testicular cords properly. It is important not to cause a hernia in the pig. The wound is then sprayed with an antiseptic.

Q. When are swine castrated?

According to the American Veterinary Medical Association (AVMA), male pigs should be castrated by 14 days of age. Most pig producers castrated their pigs between day four and 14 of age. If a producer waits longer than 14 days, AVMA recommends that pigs be castrated at least five days before weaning.

Castrating very young pigs is important for several reasons. Young pigs are nursing from a sow, and they get antibodies from the sow’s milk that help them heal and fight infection. Young pigs are also small enough that one person can safely perform the procedure. Studies have also shown that younger pigs show fewer signs of pain during castration.

Q. What methods can reduce pain?

Some pig producers use anesthesia or analgesics to reduce pain from castration. According to the USDA Agricultural Research Service, a painkiller called Lidocaine is the most common analgesic used with swine. Though anesthesia may be used in some laboratory procedures, it is not common in modern swine production.

Though analgesics and anesthesia are not officially approved in the U.S. for use in swine castration, they can be prescribed as an “extra label use” by a veterinarian.

Many pig producers do not use analgesics and anesthesia. These painkillers can be costly, and some are not practical to use in a commercial setting. AVMA does recommend that pigs castrated after 14 days of age be given anesthesia or analgesics. Research shows that pigs’ sensitivity to pain might increase over time.

Q. Are there alternatives to castration?

In the United States, nearly 100 percent of male pigs are castrated. However, some countries handle castration differently. One alternative is to harvest male pigs at a younger age. Boar taint does not usually affect meat until the boar nears sexual maturity. The drawback to this system is that the pigs are smaller when they are harvested, so more pigs are needed to get the same amount of meat. If a pig is harvested at the lighter weight of 230 lb, compared with the more weight weight of 269 lb, a producer will need to raise 15 percent more pigs to produce the same amount of meat.

In recent years, scientists have proposed the use of chemical castration and “immuno-castration.” The USDA Agricultural Research Service says more studies are needed on chemical castration. A process called “immuno-castration” could be a better alternative. Immuno-castration works by telling the body to create antibodies against a male sex hormone. This way, the pig’s own immune system can interrupt testicular function. An immuno-castration injection called IMPROVEST was approved by the FDA in 2011.

Works Cited:

“Castration-induced pain in pigs and other livestock (pdf)” from Jean-Loup Rault, et al., USDA Agricultural Research Service

“Castration of Pigs” from Dr. Allen Harper, Extension Animal Scientist, Virginia Cooperative Extension

“Extralabel Drug Use and AMDUCA (FAQ)” from AVMA

“Swine Castration” from the American Veterinary Medical Association