If you haven’t been a parent or carer for an infant in recent years, you’ll be forgiven for missing out on the oligosaccharide trend in breast milk in infant formula. These complex carbohydrate supplements mimic breast milk and act like prebiotics, promoting beneficial microbes in babies’ intestines.
Milk oligosaccharides are not just intended for humans, however. All mammals make them. And new research from the University of Illinois suggests that milk oligosaccharides can be beneficial for cats and dogs when added to pet diets.
But before the compounds were tested, scientists had to find them.
“When we first looked at this, there was only one study of milk oligosaccharides in dogs and none in domestic cats. The next few were really small studies on a single lion and a single cloudy leopard,” says Kelly Swanson, the Kraft Heinz Von Company Endowed Professor of Human Nutrition in the Department of Animal Sciences and the Department of Nutritional Sciences in Illinois.
“Our study was the first robust characterization of dog and cat milk oligosaccharides,” he adds. “Our data not only provides a better understanding of how milk meets the nutritional needs of newborn kittens and puppies, but also how it can promote gut immunity and build a healthy gut microbial community early in life.” This research appears in the journal PLoS ONE.
The fundamental study identified three predominant oligosaccharide structures in dog milk: 3-sialyllactose, 6′-sialyllactose, and 2′-fucosyllactose, the same compound found in many infant formulas today. Together, these three structures made up more than 90% of the total oligosaccharides in dog milk.
Cat milk was much more complex and balanced, with roughly 15 structures making up 90% of the total oligosaccharides. Of these, difucosyllactose-N-hexaose b, 3′-sialyllactose and lacto-N-neohexaose each accounted for more than 10%.
“Although domestic dogs and cats both evolved as carnivores, they are metabolically different in a number of ways. Although pet cats still exist as true carnivores, pet dogs are naturally omnivores,” says Swanson. “These new milk oligosaccharide data highlight another interesting difference between species and warrant further investigation to identify their role in the nutritional and health status of newborn puppies and kittens.”
Even before Swanson and his colleagues identified the oligosaccharides in cat and dog milk, the pet food industry was beginning to realize the potential benefits of these compounds as dietary supplements in pet foods. In 2019, Swiss biotech company Gnubiotics Sciences announced an oligosaccharide-like animal milk product called GNU100, but it has not been tested on animals. Swanson’s team took care of that.
In two separate studies, both published in the Journal of Animal Science, Swanson and colleagues determined the safety, palatability, and digestibility of GNU100 in dogs and cats.
First, in vitro laboratory tests with cell colonies showed no toxic effects or tendencies to cause cell mutation. There was no reason to expect toxicity, but the result met one of the basic FDA requirements for the inclusion of new ingredients in pet foods.
Next, the researchers mixed GNU100 1% with a fat source and coated commercial dry food for cats or dogs. Fat-coated diets without GNU100 were also offered as controls. When the animals were able to choose between control and 1% dishes, they went crazy about the GNU100.
“It was a huge preference with cats. They ate almost 18 times more food on GNU100 than the control food. We were just hoping they wouldn’t refuse it. You know, cats can be pretty picky,” says Swanson. “When we got the data back, it was like, wow, they really love this stuff! And so do the dogs.”
Swanson explains that GNU100 is made up of a complex mixture of oligosaccharides and peptides, small protein compounds that can make cat and dog food more appetizing.
Finally, the researchers included GNU100 at 0%, 0.5%, 1% and 1.5% in experimental diets and fed them to healthy adult dogs and cats for six months. During this time, they measured stool quality, blood metabolites, and nutrient digestibility, and assessed changes in gut metabolites and gut microbe community.
Overall, cats and dogs performed well with GNU100 with no adverse health effects. And the researchers saw shifts in the gut microbiome towards more beneficial species and their metabolite profiles.
Aside from palatability testing, the changes associated with GNU100 were as expected, showing fascinating trends in gut microbiota and metabolites that Gnubiotics would like to investigate in future studies. Swanson believes they would have seen greater benefits in a more targeted study focusing on newborn cats and dogs, geriatrics, or pets with compromised immune systems.
“In theory, these products should stabilize and feed good bacteria in the gut and limit the growth of potentially unwanted bacteria. So if an animal is being treated with antibiotics for treatment or is in a high stress situation, this product should be included in the diet keep the gut from destabilizing, “says Swanson. “Another target group for these products could be young animals to maintain beneficial bacteria in the gut when they wean their mothers. We would need to do more testing to see if the product will hold up in these target groups, but at least we now know that it is safe and well tolerated. “