Microbiome manipulations for broilers
During the course of the past six decades, the poultry industry has achieved a remarkable increase in production efficiency, largely driven through intensive breeding programs. However, this is in part at the expense of a decrease in reproductive performance and altered immune function. Consequently, a major challenge for the poultry industry is in controlling disease outbreaks caused by infectious agents.
Growth promoting antibiotics (GPAs) refer to the sub-therapeutic quantities of antibiotics, such as virginiamycin and bacitracin, that are added to livestock feed to enhance production efficiency. While the precise mode of action of GPAs has yet to be elucidated, they are thought to act through altering the microbial community (microbiome) in the gastrointestinal (GI) tract, reducing levels of pathogens causing acute enteric infections. Removal of GPAs from Canadian livestock feeds is promoting interest in the identification of efficacious alternatives.
Hundreds of species of microorganisms reside within the GI tract of chickens, which confer a mutually beneficial relationship. A major contribution of these microorganisms is their ability to extract key nutrients in addition to limiting colonization by pathogenic species. Such benefits may be particularly significant for birds with compromised immune systems and, thus, there is much interest in identifying approaches to manipulate and maintain a healthy microbiome. While recent studies have demonstrated the potential of probiotics to reduce pathogen burden in the GI tract, it is not clear how they work or which formulations are most efficacious.
The approach and experiments
Dr. John Parkinson, from the University of Toronto, and his research team aim to systematically study the precise mechanism through which probiotics operate by elucidation of active biochemical pathways. In addition, they aim to identify which probiotic species (or combination of species) provide the most beneficial effects.
They will rely on next generation sequencing to both understand the dynamics of microbial populations in the chicken GI tract as well as identify microbial and host factors that minimize pathogen burden.
The overall strategy is to examine how the microbiome of specific locations of the chicken GI tract respond to dietary regimes over the lifetime of broiler birds, and how such changes impact the abundance of major enteric pathogens, Eimeria and Clostridium perfringens.
To ensure that these findings may be translated across poultry lines, the researchers are also interested in examining the role of genetics on pathogen burden and how modern breeding practices may have compromised host immune pathways and the host’s ability to reduce pathogen burden.
In the first phase of experimentation, commercial diets in the presence and absence of GPA on commensal abundance and pathogen burden will be investigated. In the second phase, commercial diets will be supplemented with varying probiotic formulations. In the final phase, commercial diets supplemented with the three best performing formulations will be applied.
Preliminary findings and anticipated outcomes
The first phase of the experiments have been completed and results are currently being analyzed. Preliminary findings suggest that significant changes occur in the gut microbiome over intestinal sites and bird ages, but the diet and the use of antibiotics had a modest effect. The second phase is currently underway and results will lead to the initiation of phase three.
Anticipated outcomes of this research will provide validation of defined probiotic formulations that minimize the colonization of the chicken GI tract by Eimeria and C. perfringens, in addition to a systematic framework for microbiome interventions that could be readily applied in the short term to the egg laying industry. Findings will ultimately assist in the elimination of GPAs from the poultry supply chain whilst maintaining consumer confidence in the safe consumption of poultry meat.
This research is funded by the Canadian Poultry Research Council (CPRC), ALMA, NSERC Discovery, Lallemand Animal Nutrition, Pitblado Chair, Hospital for Sick Children, University of Toronto, University of Alberta, New Life Mills and Aviagen.
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