Brewing up a novel pet food using precision fermentation

There has been a growing interest in sustainable alternative protein sources for both humans and pets in recent years. 

In a collaborative project, scientists at the University of Illinois (UI) and Bond Pet Foods created a novel protein source through precision fermentation. The study is believed to be the first to use precision fermentation to produce a protein composed of both yeast and chicken protein and assess its safety in pet food.

Bond’s research and development team began by identifying proteins that were highly abundant in the muscle tissue of chickens and then cross-referencing their DNA sequence. The DNA was inserted into a specific site in the Saccharomyces cerevisiae (brewer’s yeast) genome to express the chicken protein, which was cultivated in large stainless steel tanks similar to those used in breweries or other industrial fermentation operations.

After the culture medium was removed, the biomass was harvested, heat-treated and spray-dried to produce the inactivated S. cerevisiae-containing chicken protein, which was formulated into the dog kibble. 

The findings from the six-month feeding study, published in the journal Frontiers in Veterinary Science, indicated that the brewed chicken protein was safe and nutritious at proportions of up to 40% of the dogs’ food. Dogs that consumed it showed no differences in body weight, physical condition, blood chemistry or other markers compared with those in the control group.

“It was highly digestible and there were some beneficial changes to the dogs’ gut microbes and metabolites,” said Professor Kelly Swanson, Director of the Division of Nutritional Sciences at UI. Swanson was a corresponding author on the study along with Tomas Belloso, Vice President of Regulatory Affairs at Bond Pet Foods, which funded the work.

“The main goal was to provide foundational protein for pet health, but it looks like there could be a secondary benefit from the soluble, fermentable fibres in the whole cell product for the dogs’ large intestines as well,” Belloso said.

S. cerevisiae yeast products have long been used in commercial pet food, oftentimes serving as palatants — ingredients that enhance the aroma and taste of the food, making it more appetising for pets. In addition to being a rich source of protein, brewer’s dried yeast also provides complex B vitamins, amino acids and minerals, Swanson said.

Yeast products in pet foods have other positive effects as well, such as elevating concentrations of beneficial faecal bacteria and immunoglobulin A, an antibody in the mucosal secretions of the intestines that plays a crucial role in immune functions by neutralising pathogens and other substances, Swanson and his colleagues found in prior research.

“When we were formulating these diets, we knew there was a lot of soluble fibre in them, and that was one thing I was a little nervous about — if it would cause loose stools or constipation, which is not a nice outcome for pets or their owners. And I was happy to see that the stool quality was not affected,” Swanson said.

The study has shown promising results for potential use of brewed chicken protein as a sustainable pet food option.

Image caption: On the left is a tray of the modified brewer’s yeast, and on the right is the dog kibble used in the feeding study at Illinois. Image credit: Fred Zwicky.