Whether you’re talking about pigs or people, COVID-19 or porcine reproductive respiratory syndrome (PRRS), zinc keeps coming up in the conversation as tool to help fight these serious health challenges.
“Zinc is one of the critical, foundation nutrients for effective immunity. There is no doubt that it is an important nutrition tool,” says Eric Weaver, assistant professor of animal science at South Dakota State University.
Viral Defense
Research shows zinc plays an important role in slowing the replication and spread of viral infections, says Wes Schweer, swine nutritionist with Zinpro Corporation.
Zinc is a trace mineral that impairs replication of RNA viruses, increases cilia beat (which helps expel pathogens from the respiratory tract) and improves the epithelial integrity in the lungs (helping prevent translocation of secondary bacteria into the lungs).
Gretchen Hill, retired professor of swine nutrition at Michigan State University, points out that replication of a virus is very complex, and many required nutrients play a role. The specific role of zinc, as with other nutrients, could be found in the literature in activation, mediation, etc., but this does not mean that zinc would only inhibit virus replication, Hill says.
“Just as important as the anti-viral mechanisms of zinc, zinc deficiency has also been shown to cause an exaggerated inflammatory cytokine response in response to viral infection. The role of zinc in modulating the immune response may be the most important one,” Weaver says.
Ultimately, zinc deficiency puts the host at risk for an increase in disease because it participates broadly in the effectiveness of the immune system against viral disease, Weaver explains.
“Since the immune system is one of redundant mechanisms, the evidence of increased infections and disease with zinc deficiency speaks to the importance of zinc in the body’s defenses,” he says.
Feed Intake
“As we know, stress is high in an animal when their environment is changed, such as being handled, moved, etc. There are many effects on the body of stress during these times,” Hill says. “Decreased immunity, reduced feed and water intake, etc., alter many things in the body.”
When you combine reduced feed intake with the fact that critical nutrients, especially zinc, must be utilized for the ensuing immune response, it can cause an acute zinc deficiency, Schweer says. This further impairs a pig’s ability to fight off infections.
One way to avoid acute zinc deficiency is to make sure pigs consume adequate levels of it through drinking water, even if feed intake is reduced.
“We’ve known for a long time that zinc is essential,” he says. “We feed it in every pig diet. But that’s kind of where we left it for a long time. Bringing it back to the forefront, nutritionists and veterinarians worry about a lot of different things day-to-day. Because of this, vitamins and minerals don’t get a lot of thought. But they can have some really big impacts on health and performance that they haven’t gotten as much credit for as they should.”
He believes there is room to be more proactive in supplementing zinc, especially during health challenges.
“Having a water-soluble zinc makes it easier to supplement those pigs, especially for a veterinarian or barn manager. They now have this tool available for them, and they don’t have to change the diet,” Schweer says.
A Weapon Against PRRS?
At the 2021 Leman Conference, Schweer says there was a lot of concern expressed by participants about PRRS rates this fall.
PRRS 1-4-4, Lineage 1C has persisted through the summer months and has resulted in higher rates of morbidity and mortality than usual, Schweer says. On top of that, the immune response PRRS causes opens the door for secondary bacterial infections that can be even more dangerous than PRRS itself.
“PRRS in general has been a lot different this year than in the past. When we had a farm break with PRRS recently, we conducted a field study to determine the impact of water-soluble zinc in combatting the virus,” Schweer says.
Their research showed that the addition of zinc can provide health benefits in the face of different challenges. In one study, supplementing ProPath LQ Zn in the water for pigs weaned with PRRS reduced the number of medical interventions required by 24% throughout the nursery period, including a 25% reduction in the first week.
“We know there is a seasonality component to PRRS. We need to be ready for it,” Schweer says. “No one is quite sure what to expect, but in talking with a lot of the vets at Leman Conference, there’s a bit of nervousness about how the fall is going to go. Be proactive about what’s in your toolbox for PRRS and other infections.”
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