Among the many challenges facing hog farmers in the United States is the commonly occurring incidence of post-weaning diarrhea. At best, the affliction requires the administration of antibiotics; at worst, it results in the spread of infection among weaned pigs, at times leading to more diarrhea, loss of appetite and even their death.

That motivates people like Yanhong Liu to use her expertise to find a better way. As an associate professor of animal nutrition at University of California, Davis, she researches feed-based technologies with an eye on improving animal health and taking a bite out of post-weaning diarrhea. The premise is a simple, relatable one: Make the animals stronger and healthier, and they will be better able to stave off illness.

“Our goal is to use nutrition to make pigs more resistant to enteric infection,” she says. “Once they are infected with a bacterial pathogen, antibiotics are the only cure. So, we’re researching feed additives and gauging their effectiveness in promoting growth, improving gut health and overall, in preventing illness.”

When shoats get sick

The common practice on U.S. hog farms is to have sows nurse their piglets for 21 days, after which, the offspring – now known as shoats – are weaned and placed in pens with other young pigs. The stress of moving, the process of assimilating with pen mates and the abrupt change from a liquid diet to solid feed make the shoats susceptible to bacterial infections such as E. coli. In years past, feed was laced with prophylactic antibiotics, but that practice is both undesirable and restricted now. A justifiable movement, but one that nevertheless leaves farmers to deal with the fallout – the potential loss of up to 30% of their stock.

According to Frank Mitloehner, an expert in animal agriculture and air quality, and director of the CLEAR Center at UC Davis, that’s another aspect of sustainability we need to worry about.

“When we talk about sustainability, we have to think of it in a broad sense,” he says. “Yes, it’s about reducing greenhouse gas emissions and other environmental factors from farms, but sustainability also includes animal welfare, food safety, worker health and retention, and ensuring that our farmers can make a living – that they can continue to provide food for a rapidly growing global population.” 

A food-forward approach

That line of thinking elevates the work of Liu, Yijie He and several other scientists to a new level. They recently published a study in the Journal of Animal Science that Liu believes is a promising one. By adding the probiotic Bacillus subtilis to shoats’ feed, the researchers were able to reduce severe cases of post-weaning diarrhea by as much as 5% and improve the growth of young pigs by as much as 20%. Furthermore, there were no observable side effects.

For insight into how it works, think about yogurt that adds helpful bacteria to your gut. In the same way, Liu’s lab has found the probiotic Bacillus subtilis is related to an uptick in beneficial bacteria in the ileum – the final portion of the small intestine – where the pathogenic E. coli reside. Consequently, the improved gut microbial community (Jinno et al. 2022) and bacterial metabolites (He et al., 2021) contribute to the speedy recovery of pigs from post-weaning diarrhea.

Mimicking nature’s natural defense

And there’s more good news. Liu and team are delving into other solutions to decrease E. coli infections and improve swine morbidity rates. Because pathogenic E. coli must attach to a pig’s small intestine before the disease can develop, her research team is looking at ways of heading the attachment off at the pass.

Specifically, the team is focusing on a specially crafted polymer that’s based on the naturally occurring oligosaccharides (i.e., carbohydrate chains made up of three to 10 simple sugars known as monosaccharides) that are found in pigs with Type A blood. The oligosaccharides are effective in reducing E. coli attachment to the pigs’ intestines (Kim et al., 2022); consequently, pigs fed with this special oligosaccharide have lower rates of diarrhea. If the lab-created polymer – that’s based on nature’s carefully crafted defense mechanism – can effectively interfere with the initial attachment of pathogenic E. coli and rapidly eliminate the harmful bacteria from the gut, the infection might be avoided.  

Work that’s more than academic

Although this manner of work is happening at the university level, it stands to benefit millions of people outside the realm of academia. According to the USDA, with 72.9 million hogs and pigs, the United States is the world’s third-largest producer and consumer of pork, making the issue of animal health a significant one. For that reason alone, Liu’s work, including the ability of Bacillus subtilis and oligosaccharides-based products to cut down on disease and death among shoats, is especially relevant.  

And it’s research that’s already being put into play. Based on studies by Liu and others, the probiotic is already being marketed to farmers, gaining acceptance from the swine industry at the same time. In addition to its potential to lower cases of post-weaning diarrhea, Bacillus subtilis is affordable and shelf stable, criteria that any remedial measure must meet, she says. The oligosaccharides-based polymer (that’s based on the carbohydrate chains in Type A blood) is in the midst of further evaluation, but its potential to fight diarrhea in post-weaned pigs is exciting.

“Whatever we develop and recommend for producers, we have to consider benefits, stability and cost,” Liu says. “If any one of those is missing from the equation, it’s not going to add up to a viable solution.”

The CLEAR Center receives support from the Pork Checkoff, through the National Pork Board.