On their own, large roundworms can inflict substantial harm on pig performance and a producer’s bottom line.
However, new research shows the negative effects of roundworms can go much further, actually reducing the ability of a pig’s immune system to fight viral and bacterial pathogens that cause diseases such as PRRS, swine influenza and ileitis – leaving today’s pigs more vulnerable than many producers and veterinarians realize.
Recent research has shown roundworms migrating within a pig can skew the immune system away from its normally efficient method of controlling disease pathogens. This can give pathogens the foothold they need to become full-blown cases of disease.
In addition, there is a suggestion that increasing levels of roundworms could interfere with routine herd-health protocols such as vaccinations.
Specifically, research could help determine the impact roundworms have when they significantly compromise a pig’s immune system, rendering it unable to produce the required level of the antibodies to establish protective immunity.
James Arends, a consulting parasitologist based in Willow Springs, N.C., said this new information should encourage producers and veterinarians to discuss the increasingly serious threat posed by parasites.
“Over the past 15 years or so, we have focused mainly on performance in our genetic selection at the expense of a healthy immune system in pigs. This had led to today’s pigs being more like thoroughbreds instead of Clydesdales – they just aren’t as capable of fighting off health threats such as roundworms,” he said.
According to research from the University of Nebraska, most producers should be concerned about roundworms in their herds. A study there showed large roundworms infect 70 percent of Midwest swine operations.
This is even more significant because research by Stephaan De Bie of Belgium indicates roundworms can cause losses of up to $4 per head from decreased performance.
“Together, this research clearly underscores the need for producers to take preventive steps to protect the health and performance of their animals,” Arends said.
Roberto Garcia, global technical services director with Merial in Duluth, Ga., said producers need to take into account facility age, cleanliness and downtime between groups when dealing with roundworms.
“Aging buildings where floors and other structures begin to degrade can promote the establishment of parasites. This is because roundworm eggs can easily stick to rough, uneven surfaces,” he said.
Because a single female roundworm can produce more than 250,000 eggs per day, controlling the spread of eggs is a big task.
Garcia said he advises producers to implement control programs for rodents, insects and birds, all of which can spread infection throughout an operation. Even human traffic can spread roundworm eggs.
Although visible signs of roundworm infections in a herd are often hidden or attributed to other diseases, swine health experts recommend producers implement an ongoing roundworm-monitoring program.
This typically includes taking fecal samples at least once a year to detect the presence of roundworm eggs. Slaughter checks of livers are also valuable as they can indicate the damage done by migrating larvae.
“Proper surveillance is crucial, because the few clinical signs observed with roundworm infections – unthrifty appearance and poor weight gains – are too general to be of diagnostic value,” Garcia said. “Without a parasite monitoring program in place, producers and veterinarians can underestimate the level of infection or miss it altogether.”
To get the best results from a strategic treatment program for roundworms, Garcia said producers need to anticipate when their herd will be infected and then consider a twice-yearly medication treatment.
For grow-finish pigs coming from an infected sow herd, that means using a parasiticide such as Ivomec Premix for Swine when the pigs arrive.
If the sow herd is not infected, but grow-finish facilities are, pigs should be treated 21 days after arrival. Feeder pigs should be treated upon arrival and isolated for seven days.
Sows, gilts and boars should be treated twice a year starting on the same day.
“To get the most from a treatment program, producers should focus on accurate dosing, full compliance and good sanitation,” Garcia said.
Keeping an eye on pig performance, as well as product efficacy, Garcia pointed to a study published in “Veterinary Parasitology” that showed pigs treated with Ivomec had significantly higher average daily gains and 22 percent greater efficiency in feed conversion than non-treated infected pigs.
“This is just one of many well-controlled efficacy and productivity studies conducted under field conditions that have demonstrated to producers the value of parasite control with Ivomec,” he said.
Arends said the research connecting roundworms with decreased disease immunity should get the attention of the pork industry.
“If your pigs have parasite-weakened immune systems and then get Swine Influenza Virus or PRRS, you could have a herd health and pig flow train wreck because there’s very little room for production errors with today’s marketing schedules,” he said. “Hopefully, producers will get the message that parasites are a serious problem worthy of monitoring and controlling.”