While the idea that a food preservative used in bacon could be fed to feral swine to reduce population growth may seem a little odd at face value, it is none-the-less being considered by the U.S. Department of Agriculture for just that purpose.

Sodium nitrate is the common salt preservative used in bacon and other types of meat, a substance that has little or no negative effect in people because the human body is rich in enzymes that stop the nitrate from preventing red blood cells grabbing oxygen from the system. But wild animals, including swine, do not produce the same kind of enzymes in sufficient number, so sodium nitrate might serve as an effective poison if target species consume enough of it.

The idea isn't a new one. Sodium nitrate has been used in both Australia and New Zealand for years to help control spiraling feral swine populations. USDA testing could take place in Texas later this year, according to Bryan Black with the Texas Agriculture Department.

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Officials say for sodium nitrate to be effective, wild pigs would need to digest large amounts of the substance over a short period of time. If they do, the sodium nitrate can induce symptoms and results similar to carbon dioxide poisoning. Feral swine become uncoordinated, lose consciousness and eventually die.

TDA officials say they are committed to working with Texas Parks and Wildlife officials in finding a way to reduce feral hog populations across the state. Wild swine are credited with causing as much as $500 million in economic damage in Texas every year. Texas’ feral swine growing population already numbers well over two million. Texas, in fact, can lay claim to having nearly as many feral swine in the state as the total number of feral swine in the remaining 38 states with damaging wild hog populations.

Damage costs are high

Estimates show feral swine in the United States cause more than $1.5 billion in damages and control costs each year. Damage includes rooting and wallowing that cause property damage and erosion to river banks. Feral swine eat and destroy field crops such as corn, milo, rice, watermelon, spinach, peanuts, hay, turf, and wheat. They are also efficient predators and, when given the opportunity, prey upon young livestock and other small animals, such as ground-nesting birds.

Controlling feral swine population is a major task according to USDA Biologist Fred Cunningham at the National Wildlife Research Center field station in Starkville, Mississippi. He says to maintain a constant population of feral swine, up to 70 percent of feral swine in an infested area must be eradicated.

In spite of escalated trapping efforts and intensive hunting over the last two years, population numbers across Texas continue to grow.

Earlier this year, USDA Undersecretary Edward Avalos announced that USDA is providing additional funding this year to reduce the devastating damages caused by feral, or free-ranging, swine. The $20 million program aims to help states deal with a rapidly expanding population of invasive feral swine.

"Feral swine are one of the most destructive invaders a state can have,” said Avalos.  “They have expanded their range from 17 to 39 states in the last 30 years and cause damage to crops, kill young livestock, destroy property, harm natural resources, and carry diseases that threaten other animals as well as people and water supplies. It’s critical that we act now to begin appropriate management of this costly problem."

Cooperating agencies

The Wildlife Services (WS) program of USDA’s Animal and Plant Health Inspection Service (APHIS) is leading the effort, tailoring activities to each state’s circumstance and working closely with other Federal, State, Tribal, and local entities. WS works directly with states to control populations, test animals for diseases, and research better methods of managing feral swine damage, including the use of sodium nitrate. A key part of the national program will include surveillance and disease monitoring to protect the health of domestic swine.

Avalos says feral swine have become a serious problem in 78 percent of all states in the country, carrying diseases that can affect people, domestic animals, livestock and wildlife, as well as local water supplies.

In addition to killing young animals, their characteristic rooting and wallowing damages natural resources, including resources used by native waterfowl, and archeological and recreational lands.  Feral swine also compete for food with native wildlife, such as deer, and consume the eggs of ground-nesting birds and endangered species, such as sea turtles.

"In addition to the costly damage to agricultural and natural resources, the diseases these animals carry present a real threat to our swine populations,” Avalos added.  “Feral swine are able to carry and transmit up to 30 diseases and 37 different parasites to livestock, people, pets and wildlife, so surveillance and disease monitoring is another keystone to this program."

He says as part of the national program, APHIS will test feral swine for diseases of concern for U.S. pork producers, such as classical swine fever—which does not exist in the United States—as well as swine brucellosis, porcine reproductive and respiratory syndrome, swine influenza, and pseudorabies.  Ensuring that domestic swine are not threatened by disease from feral swine helps ensure that U.S. export markets remain open.

While USDA-APHIS has yet authorized widespread use of sodium nitrate, field testing of the substance is expected to begin as early as this year.