Properly prepare gilts to match farm’s Mycoplasma status, By Cary Sexton, DVM, Four Star Veterinary Service

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After living with Mycoplasma hyopneumoniae (M. hyo) for years, producers now know that maintaining a stable M. hyo status is key to reducing the disease’s impact.

“The more we know about M. hyo, the more we realize how important it is to have a gilt properly prepared for either a negative or a positive farm and not mix those statuses,” said Cary Sexton, DVM, Four Star Veterinary Service in Kinston, North Carolina.

Synchronize M. hyo status

“First, you need to understand the status of the sow farm the gilts are going to,” Sexton said. “Then, the gilts need to be properly prepared, either exposed and vaccinated or both if going to a positive farm or kept clean if going to a negative farm. I would recommend working with your veterinarian to determine the proper sow-farm status.”

Most commercially available genetic stock now has a negative status, he explained. Any sow farm with a different M. hyo status will need a plan to synchronize health of the gilts before they are mixed with the herd.

“There are multiple ways to synchronize, but it has to be some type of exposure,” Sexton said. “Exposure should be at weights around 40 pounds to make sure it’s long enough for the animals to get through an infection and clear the active shedding phase. If you put shedding gilts into a stable-positive farm, it could turn clinical.”

The most common exposure methods are direct inoculation with a live M. hyo culture or fogging with lung homogenate material.

“Direct inoculation is the most labor intensive,” he said. “You have to catch each animal and inoculate it. In a barn with 1,000 gilts, it is a full day of work versus fogging that only takes a couple of hours after the environment is readied for the procedure. The most difficult part is getting exposure done consistently on an every-group basis.”

Mounting immune response

After exposure, gilts must be closely monitored for illness, including secondary infections.

Animals sickened by exposure need to be treated to help them recover and to ensure the infection doesn’t become chronic, Sexton explained.

“You want them to get exposure and mount an immune response while continuing to grow. Ultimately, they will stop shedding or shed at a very low level by the time they are ready to move onto the sow farm,” he said.

Because M hyo is a very slow-growing pathogen, it may take 7 months to complete this process. Producers must plan for adequate time and space to handle gilts for these extended periods. This time lapse increases with natural exposure as each new exposure results in resetting the time clock.

Eliminating M. hyo

Interest in M. hyo elimination is growing as producers learn about its benefits. A negative herd could see a $5-to-$7-per-market-hog improvement from when it was M. hyo positive, particularly in the growing-pig segment of production.

Two types of operations are more interested in eliminations, according to Sexton. A farrow-to-finish farm will recoup the most benefits by owning hogs to market, while a farrow-to-wean operation sees a benefit in the health of weaned pigs sold to customers.

Improvements in testing methods for M. hyo also help make eliminations successful. Deep-tracheal swabs examined by polymerase chain reaction are reliable and repeatable, he added.

If an operator is considering an elimination program or wants a change in the M. hyo status, Sexton recommends first determining the herd’s status. Then he or she should meet with a veterinarian to discuss options for the farm.

“Have a conversation about wanting to make a change in M. hyo status or looking for a different source of genetics,” he said. “You need to [identify] the cost-benefit ratio of each option. Is it worth the time and money to do an elimination? Or is there a way to get exposure of these animals to produce a stable-positive farm? You may be surprised which one rises to the top.”