Boar taint is a very strong odor and taste that 75 percent of consumers can detect in pork produced by sexually mature (intact) males. The odor is said to be similar to hog manure or urine. It is only noticeable once meat is cooked and not a problem in cold meat products.

Four years ago, USDA’s Food and Drug Administration (FDA) approved a drug used to control boar taint that had been available globally for about five years. Called Improvest, the drug uses a protein to cause the pig’s immunization system to produce an antibody that reduces the production of a steroid and an amino acid responsible for producing boar taint.

Though her company would not comment on actual sales, Christina Lood, senior marketing communication manager for the U.S. Pork & Poultry at Zoetis, characterized interest in the drug product as “significant.”

Benefits of drug

There are a number of advantages to using the drug versus more traditional means of castration. Perhaps the most significant is the 4.5 percent increase in average daily gains experienced when feeding intact males, Mike Senn, senior veterinarian of Zoetis’ pork technical services team, said.

“There is no difference in quality or composition of the meat,” he said, “and there is no hormonal activity associated with the drug.”

Another advantage is reduced chance of infection. Because it is administered by injection, wound infections are virtually eliminated and fly problems are no longer as much of a concern. Improvest’s mode of action inhibits production of androstenone – a testosterone steroid – and skatole, an amino acid (tryptophan) derivative.

Androstenone is a sex pheromone produced in the male’s testicles at sexual maturity that collects in the salivary glands. Skatole is produced in pigs’ hind guts and contributes to the smell of hog manure. Levels of skatole are much higher in males versus females because testicular steroids block skatole’s breakdown by the liver.

These two compounds’ presence in male pigs is one of the major reasons why castration is so prevalent on commercial hog farms.

Improvest requires a two-dose, 2 mL subcutaneous injection regimen, Senn said, with the first dose administered after pigs are nine weeks of age. The second dose is administered three to 10 weeks prior to slaughter.

This is not a withdrawal time, he said. “It relates to how long it takes for the immune process to occur and has nothing to do with drug residues.” Two injections cost $4 to $5 per pig, total.

Cover photo: alffoto/istock

Before producers can administer the drug, they must undergo a no-cost, mandatory, online training and certification process, overseen by Zoetis representatives. It consists of online lessons and quizzes, followed by an in-barn certification to teach farm personnel how to administer the drug.

Feeding intact males does not require facility modification, Bill Beckman Jr., an Improvest area application manager, said. “All you really need is some kind of barrier or sort-board to separate the animals while administering the drug,” he said.

Beckman also reported that boar behavior changes significantly within seven to 10 days of the second injection. Activity normally associated with sexually maturing boars – vocalization and mounting – subsides and declines completely.

“At 14-21 days after the second dose, we guarantee the pigs have made the transition,” Beckman said. “They are calm, content, spend more time at the feeder and become kind of like lazy boys.”

Cover photo: Steinbergpix/istock