Poultry Microbiota Insight: Part 1 – Meet the microbes

The gut microbiota includes a majority of commensal species as well as potential pathogenic ones. It is composed of thousands of different strains and species of bacteria, yeasts, viruses and archaea.

Each part of the poultry digestive tract offers a different habitat in terms of nutrients and pH conditions but also feed retention time. From the crop to the caecum, the composition, concentration, and diversity of the microbiota is highly variable (Fig. 1). However, in birds, microbiota diversity is fairly low when compared to bigger animals, probably due to the short transit time. Typical retention time for a 29-day-old broiler is between 4-5 hours compared to humans where the average is 20 hours.

Establishment of the chick’s microbiota takes several days after hatching, a time when the birds are particularly sensitive to enteropathogen contamination.

The primary roles of the microbiota are:

1. to aid in digestion
2. to safeguard the organism against pathogens and reinforce immunity.
   

   Fig1. Estimated microbial population density along the poultry digestive tract

The poultry gut microbiota is a fragile ecosystem that can be disturbed by many factors, such as vaccination, pathologies, drugs, antimicrobial treatments, heat stress, sexing, feed transition, building changes, etc.

A method to assess the equilibrium of the gut microbiota at farm level is to analyze the fecal microflora and look at the ratio between two bacterial populations: one beneficial, such as Lactobacilli; and the other, a potential risk, such as coliform. Fecal microflora analysis can be a good indicator of a flock’s health status. It has been shown in various conditions that feeding selected probiotic bacteria to poultry helps improve the ratio between lactic acid bacteria and enterobacteria populations.