Bacteriophages as a tool to improve poultry gut health

The concept of “gut health” is not clearly defined by the scientific community, but generally it is considered the balance of physiological, microbiological, and physical functions – which allows the intestine to be in a homeostasis status. It should have a diverse, balanced, and functional community of beneficial and pathogenic microorganisms (microbiome), a robust intestinal barrier for physical and chemical protection and an effective immune system that acts locally and systemically.

Intestinal barrier integrity

The intestine has the longest interface with the external environment being constantly vulnerable to infections. When birds are infected, for example by enteric pathogens, the intestinal barrier integrity and microbiome can be disturbed, resulting in dysbiosis, and the immune system is triggered, being energetically expensive for the host.

This dysbiotic event results in inflammatory response and nutrients malabsorption, that was already associated to reduced performance of affected poultry, decreased farm profitability, and impairment of birds’ welfare. Even subclinical levels of a pathogen, such as Salmonella spp., can disrupt intestinal health and decline productivity.

Since the ban on the use of antimicrobials to promote chickens’ growth and prevent infections in Europe, United States and other countries, there has been an increase in poultry enteric illnesses (Kogut, 2019) due to dysbiosis. Some additives are used to support the gut health and the immune system of the host, for instance probiotics, prebiotics, organic acids, enzymes and now, bacteriophage brings hope as a new alternative.

Bacteriophages

Bacteriophages, or phages, are beneficial viruses, naturally found in several environments. They are an important part of the global microbiome protecting animals and humans from the overgrowth of certain bacterial populations. In the animal production industry, phages can be employed to prevent or reduce the presence of specific bacteria, including Salmonella spp. and Avian Pathogenic E. coli (APEC).

Two types of phages are crucial in this context: lytic and lysogenic. The lysogenic is a dormant virus, embedded in the bacterial cell and able to live-off of the bacteria without destroying it – this one is not suitable for animal production. The lytic phage is virulent and will infect the target bacteria, force it to multiply their DNA until it causes the lysis of the cell. As per the destruction of the pathogen, it will result in the reduction of bacteria counts.

Want to learn more about how bacteriophages work? Watch this video