Alternatives to Antibiotics Could Improve Animal Gut Health
Researchers are looking to probiotics, prebiotics, postbiotics, feed additives, and feed enzymes to help keep animals healthy, an effort which could temper consumer fears over antibiotic use in the food supply.
The food industry has been undergoing a course correction these past several years, with companies removing trans fats, excess sugars, and other unhealthy ingredients from products. Removal of antibiotics from livestock animals has been part of that effort.
“The public has a negative perception about antibiotics in agricultural animals,” Ryan Arsenault, an assistant professor in the University of Delaware’s department of animal and food sciences told Seeker. “However, there are no antibiotics in food animal products that go to the consumer. Even with chickens raised with antibiotics in their feed, these antibiotics are withdrawn well before the chicken is sent to processing, so there will be no residual antibiotics in the chicken. This is the same for dairy cows and their milk.”
The potential for the development of antibiotic resistance in consumers remains a debated health risk, though, so the livestock industry has been working to eliminate as many antibiotics as possible from their animals. At the very least, informing consumers that a product is antibiotic free has proven to be an effective marketing tool.
Now the challenge is to keep animals raised for human consumption healthy, without all of the drugs.
Arsenault’s lab members are investigating some surprising possible solutions.
Team member Casey Johnson has been studying yeast cell wall extracts, and how they may help to prevent necrotic enteritis, otherwise known as inflammatory dead-gut disease, which is a threat to chickens.
“Yeast are a fungus,” Arsenault said. “Their cell wall contains different components than bacteria or viruses, thus they engage different receptors on the surface of the epithelial and immune cells of the gut.”
He explained that, when purified, yeast cell-wall extracts can be fine-tuned to target particular receptors in the animal’s gut. They do not engage the immune response like a bacteria or virus would, but instead appear to “prime or modulate” the immune system, helping it to better fend off pathogens.
Lab member Bridget Aylward has been working with forskolin, a plant extract normally thought of as a weight-loss supplement for humans. Prior studies show that forskolin increases levels of a signaling molecule called cAMP that is important in a number of cell functions, including response to hormones. It may serve as a link between the animal’s metabolism and immune system.
Members of Arsenault’s lab are also looking at additional probiotics, prebiotics, postbiotics, feed additives, and feed enzymes as alternatives to antibiotics.
Keeping animals healthy is clearly important for a number of reasons. One is economics, but another is animal welfare.
“The goal is a healthier and disease-free animal,” Arsenault said. “If we can prevent diseases by improving gut health, we improve the quality of life of the animal and improve production. Our goal is that win-win.”
He and his team are focusing on the gut because more than 50 percent of an animal’s immune system is found there. This is true for humans as well. The other 50 percent consists of immune organs like the spleen and white blood cells that circulate throughout the body. Both the oral and the gut microbiomes are key to immunity.
“The oral microbiome, like the gut microbiome, provides protection from pathogens by not allowing them a place to reside, referred to as competitive exclusion,” Arsenault explained. “Beyond this, the stomach and its acidic environment is very important to protect the gut from pathogens. Beyond that, the gut microbiome helps to protect the gut from pathogens that get through.”
The gut, by its nature, must be permeable, because it needs to allow nutrients to get through.
“This provides an opening for pathogens to get through as well,” he said. “Because the guts of many animals are similar to humans, and our interactions with both wild and domestic animals are very extensive, zoonotic diseases can pass from animals to humans.”
The most common zoonotic diseases are those that affect the gastrointestinal system. They may result from pathogens such as Salmonella, E. coli, and Campylobacter.
Ideally, the animal’s immunity will be primed well enough to fend off these health threats. Research over the past several years has shown that the acquisition of effective oral and gut microbiomes early in life can benefit the individual over the course of an entire life span. Such microbiomes tend to stabilize a bit more as the individual ages, making it more challenging to change them over time, even though they are not fully fixed.
As a result, Arsenault and his team are also looking at ways of encouraging the development of proper microbiomes in young livestock animals.
“It may be possible to orally provide the newly born or hatched animal with a mixture of beneficial bacteria to get them off to the best start,” he said. “That is just one example.”
He added there are minimal risks to consumers associated with such microbiome tinkering, since the additives are only affecting the animal’s microbiome and gut immune response. The additives would therefore not necessarily show up in any animal product sold to consumers.
Improving the health of livestock animals through these antibiotic-free means could also lead to improved medical treatments for humans.
Arsenault said there’s a long history of research on animals leading to health benefits for humans: The discovery of B-cells, virus-induced cancer, interferon used to treat viral infections and multiple sclerosis, and work on second-hand smoke in embryos all happened in chickens.
“We think our research will be applicable to human gastrointestinal health as well,” he added.
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