Recent facility improvements at the University of Nebraska-Lincoln have given a boost to the university’s swine research, critical to the state’s industry and efforts to feed a growing global population.

New gate feeders in the “pig room” in the Animal Science Complex, funded by the Nebraska Pork Producers Association, were installed in late winter to provide more space for research.

Pork is a key food source for a growing world population, parts of which already struggle with food insecurity. It’s the most consumed meat worldwide, with demand expected to increase 37% by 2050. Researchers and the livestock industry are working to increase production to meet this need by focusing on animal health and production efficiency.

Nebraska is a key state in that effort, with a variety of research projects underway to boost animal health and overall production.

“Interest and momentum in swine research are growing at UNL, and that is in part due to their importance for agriculture in the state, and nationally and internationally, but also they’re fantastic biomedical models,” said Amy Desaulniers, a reproductive physiologist.

Focusing on boars

Traditionally, research on reproductive productivity has focused on sows over boars, but Nebraska researchers are breaking that mold. For example, the project for which the new gate feeders were needed is an attempt to develop boars that are more genetically tolerant of gestational heat stress.

Desaulniers, an assistant professor in the School of Veterinary Medicine who leads the project, said direct exposure to summer heat stress dramatically impairs sperm production in adult males. Exposure to heat stress in utero also impairs sperm production.

Boar fertility is critical for the swine industry, which relies almost exclusively on artificial insemination. A typical boar sires an average of 8,398 progeny per year, compared to 23 progeny per year for a sow. Nebraska is home to 21% of the nation’s boar stud population.

“The boar has the greatest cumulative impact on swine reproductive performance and drives genetic progress in the herd,” Desaulniers said.

Ultimately, Desaulniers’ research could lead to new pharmacological approaches, genetic tests or dietary changes that support reproductive health.

The new gate feeders will increase the size of pens available for market-weight pigs and expanding the space for housing additional animals, said Desaulniers, assistant professor of veterinary medicine and biomedical sciences. She recently received an Early Career Excellence Award from UNL’s Agricultural Research Division.

Brett White, associate professor of animal science, is also researching the boar’s role in reproduction. His goal is to determine as early as possible which boars are subfertile and remove them from the artificial insemination programs that typically pool semen from two to five animals.

Subfertile boars limit reproductive efficiency and are best suited to being culled as market animals and removed from the stud population early, White said.

His research explores the role of a certain hormone produced throughout boars’ bodies, but especially in the testes. It appears this gonadotropin-releasing hormone II and its receptor affect testosterone release.

“We could potentially identify subfertile boars at a younger age or create additives for semen extenders to lengthen the amount of time that sperm remain viable, improving reproductive efficiency and thus overall profitability for swine producers,” White said. “Litter size is the name of the game.”

Improving pigs’ gut health

Other researchers are studying pigs’ diets to see if they can produce healthier animals without using antimicrobials, excessive use of which has led to antimicrobial resistance in animals and the emergence of drug-resistant pathogens. The United States is the second-largest consumer of antimicrobials for livestock.

Veterinarian Natalie Erker, who’s working on her doctorate, is researching how pigs’ diets could be altered to modulate their gut microbiome and reduce the need for antimicrobials. Her research uses Jerusalem artichoke tubers as a source of prebiotic fiber.

“Through nutrition and diet, are we able to promote health, especially with the need now of reducing antimicrobial usage in our agricultural animals? In an ideal world, we’d find a way to create a more robust animal from the start without the use of any antimicrobials. We’ve certainly made great strides in moving away from them,” Erker said.

Olivier Munezero, another Ph.D. student, also is focusing on antimicrobial use, researching  alternatives that could replace antimicrobials in pigs’ diets. He’s been experimenting with replacing the 3% corn oil content in the pigs’ feed with 3% black seed essential oil.

The switch shows promise, he said. With the experimental feed, there was no growth of salmonella or E. coli bacteria.

Other researchers are also looking to the pigs’ gut to improve productivity. Duncan Paczosa, another Ph.D. student, is researching the effects of zearalenone, a mycotoxin,  on the gut microbiome.

Zearalenone, commonly found in grains such as corn, can contaminate animal feed and cause reproductive issues and reduce piglet survival. Paczosa said research indicates certain microorganisms can degrade or modify mycotoxins. His work seeks to reinforce those microorganisms, such as the bacteria Lactobacillus, to help maintain a healthy pig gut.

“If we can reinforce that bacteria within the microbiome, we can help the pig fight off mycotoxins, because mycotoxins are very hard to avoid within the feeds,” Paczosa said.

Making strides toward better vaccines

Hiep Vu, associate professor of animal science, studies how to protect against the influenza virus in pigs.  

Viral diseases are a major source of economic losses for swine producers, with swine influenza and porcine reproductive and respiratory syndrome virus collectively costing the U.S. swine industry more than $1 billion annually.

Vaccination is the most cost-effective tool for controlling viral diseases in livestock, but traditional vaccines, such as inactivated-virus and live-attenuated vaccines, often prove inefficacious or are time-intensive to develop, Vu said.

He is developing a versatile “plug-and-play” vaccine platform that can rapidly adapt to develop new vaccines to control viral pathogens. He’s already developed a lipid nanoparticle formulation, or LNP, to encapsulate DNA plasmids encoding viral antigens. DNA vaccines are highly stable, cost-effective to produce and safe for animal use. These features enable DNA vaccines to gain regulatory approval more quickly.

Using swine influenza virus as a model, Vu demonstrated that a single dose of the LNP-DNA vaccine induces a strong immune response in pigs and provides complete protection against the virus. He has also applied this approach to the avian influenza virus and obtained similar results.

“This underscores the versatility of this vaccine platform to address multiple viral pathogens affecting different animal species,” Vu said.

Eric Weaver, director of the Nebraska Center for Virology and professor in the School of Natural Resources, is a leading expert on  swine vaccines. His work addresses several drawbacks with current vaccines: They are infrequently updated, induce strain-specific responses and have limited duration of protection.

His research team has used a computational program to analyze data on every available mutational variant of hemagglutinin, a viral protein, and has made progress on developing a vaccine that would fight a much wider variety of strains than currently available vaccines.

The goal is to produce vaccines that will protect against a variety of strains and have longer periods of efficacy. This has implications for human health, since swine influenza is a zoonotic disease that can transmit to people. Pigs act as “mixing vessels,” where various swine and bird influenza strains can reconfigure and become transmissible to humans. 

UNL is a leader in this research.

“What we are doing in the lab here at Nebraska is setting the bar on an international level,” Weaver said.

Monitoring animal health and wellbeing

Ten years ago, Ty Schmidt, associate professor of animal science, and others in UNL’s Department of Animal Science created NUtrack Livestock Monitoring, a vision-based computer program that utilizes precision livestock technology to identify and continuously track the behaviors of group-housed livestock. Researchers have used the tool to improve swine health, welfare and production efficiency.

The technology tracks individual pigs’ behaviors  and can be adapted to identify and track more complex behaviors, Schmidt said.

Ultimately, Schmidt said, the technology could be commercialized and used by the swine industry to identify animals that are sick or engage in problematic behavior like fighting. If producers can identify sick animals more quickly, they can treat them sooner.

“Someday, somebody’s going to have a system where they pull up a sheet that’s printed out first thing in the morning. It says, for example,  ‘You have eight pigs in this pen that need to be evaluated,’” he added.

“The healthier the animal, the more productive they’re going to be, the more efficient they’re going to be. We’re hoping it will have a huge benefit for producers.”

Animal Science Institute of Agriculture and Natural Resources Veterinary Medicine and Biomedical Sciences