Red Osier Dogwood: A Potential Antibiotic Alternative

Monday, March 24, 2025

Showing promise for prebiotic properties in broiler chickens.

By Emily Mckinlay

Antibiotic resistance is an increasing concern for livestock producers in Canada. In response, nutrition researchers have been investigating the potential use of prebiotics and probiotics as antimicrobial alternatives.

Dr. Deborah Adewole, assistant professor in monogastric nutrition and metabolism at the University of Saskatchewan, has focussed her research on developing and investigating alternative options to address antibiotic resistance. Prebiotics and probiotics may improve gut health and could have the ability to replace antibiotics.

“Prebiotics and probiotics are two different types of additives,” says Adewole.

“Both are used to promote the gut health of animals, including poultry, swine, and other food animals, but they have different modes of action.”

Prebiotics and probiotics both promote a healthy gut microbiome.

“Prebiotics are polysaccharides or oligosaccharides that cannot be digested in the small intestine,” explains Adewole.

“They go into the large intestine. Because the large intestine environment is conducive for microbial fermentation, these products are fermented. The bacteria will produce metabolites that provide health benefits to the host.”

The metabolites produced include short-chain fatty acids such as butyric, propionic, and acetic acids.

“These help to maintain the integrity of the intestine and make it more functional to absorb nutrients and keep pathogens out,” says Adewole.

“Prebiotics are food or substrates for micro-organisms in the gut. They increase the abundance of beneficial microbes and reduce pathogens.”

While prebiotics fuel microbes, probiotics are living microbes.

“Probiotics are live microorganisms that are beneficial to the host, including bacteria, fungi, or yeast,” says Adewole.

“Not all microorganisms can be used as probiotics. They need to be selectively added. There are many bacteria types that are used. Examples are bacillus, lactobacillus, and bifidobacteria. They have been selected as probiotics because they don’t cause harm to animals or humans and are usually beneficial.”

These additives can be delivered to poultry a few different ways.

“Most prebiotics and probiotics would be included in the feed. Some can also be applied in water or in ovo,” says Adewole.

“For in-ovo administration, the prebiotic or probiotic can be injected into the egg of a developing embryo. It’s not yet popular, but it’s an option.”

Research has also been investigating the feeding of these additives to broiler breeders, which then pass the benefits to their offspring and help develop resistance to infection in early life.

Recently, Adewole has been exploring the use of red osier dogwood as an antibiotic alternative.

“The red dogwood plant is an ornamental shrub that grows naturally in some Canadian provinces.

“This plant has been used as traditional medicine by humans to treat diseases in the past in Canada. The extract could also provide beneficial effects because it contains antioxidants.”

Adewole approached this investigation with four studies.

The first study followed broiler chickens over 45 days on four treatments: A control diet, a diet with antibiotics, a diet with 0.1 per cent inclusion of red dogwood extract, and a diet with 0.3 per cent inclusion of red dogwood extract.

“We found that both inclusion levels of red dogwood extract caused improvements in digestibility of amino acids. We also found that protein and fat digestibility were improved,” says Adewole.

“We found that both inclusion levels increased the absorptive area of the jejunum, the longest part of the small intestine.”

In the second study, Adewole added a bacterial challenge using bacterial lipopolysaccharides (LPS) to stimulate the animals’ immune response, received by half of the broilers.

The four treatments in this study were a control group, a group that received antibiotics, a group that received 0.3 per cent inclusion of red dogwood extract, and a group that received 0.5 per cent inclusion of red dogwood extract.

“We used an increased inclusion level to see if a higher level of red dogwood extract was needed to fight the bacterial challenge,” explains Adewole.

In this study, the team observed that the group that received 0.3 per cent inclusion of the extract had greater villi height to crypt depth in the intestine, indicating greater nutrient absorption capacity in groups that both received or did not receive the bacterial LPS challenge. They also observed an increased relative abundance of lactobacillus, a beneficial group of bacteria.

“Lactobacillus is one example of bacteria used as a probiotic.

“This result means that red dogwood can function as a prebiotic. It may not be classified as a prebiotic, but it has prebiotic properties.”

In the third study, Adewole’s group challenged the broilers with live salmonella instead of bacterial LPS, using the same treatment groups as the second study.

The team found that inclusion of 0.3 per cent red dogwood extract stimulated production of white blood cells, promoting the numbers of leukocytes and monocytes.

They did not observe improvements in growth performance, but this study demonstrated the ability of red dogwood extract to mitigate infection.

In the final study, Adewole evaluated the effect of heat stress on the broilers.

This study had three treatments: A control group, a group provided antibiotics, and a group provided 0.3 per cent inclusion of red dogwood extract. The 0.5 per cent group was omitted because it did not offer additional benefits in the previous studies.

During heat stress, Adewole found that inclusion of red dogwood extract improved growth performance, average daily gain and feed conversion. They also noted increased fecal bacteria relative to the antibiotic treatment group.

“Inclusion of 0.3 per cent red dogwood extract may function as an alternative to antibiotics and functions in improving performance and intestinal health,” concludes Adewole.

Based on the results of her research, Adewole is eager to see red dogwood extract grow as a feed additive in the poultry industry.

“Based on this research, some progress been made already. It has been registered as a veterinary product with Health Canada at an inclusion level of 0.3 per cent,” says Adewole, who notes a company in Manitoba is conducting the extraction process.

“I look forward to seeing more progress being made with CFIA to allow more usage by farmers and to promote the inclusion of red dogwood extract in their feeding program for antibiotic reduction.” BF