The intestinal microbiota is defined as a complex community of microorganisms of various species living in the digestive tract of animals. They represent the largest reservoir of mutual microorganisms. They interact with each other, with the external environment, and with their host. They play a key role in the host’s digestion and defenses.
A complex ecosystem
The swine gut microbiota encompasses a large and diverse population of bacteria.
- Recent studies have shown a common ‘core’ microbiota in pigs comprised of bacteria genera such as Prevotella, Clostridia, Alloprevotella, and Ruminococci.
- This microbiota is established from the first days of the piglet’s life from microorganisms present in the environment and through contact with the mother.
- Microbial diversity increases along the gastrointestinal tract. Different parts of the gut have specific roles in nutrient digestion, and they host very specific microbial communities adapted to their micro-environment. For instance, major fermentation processes take place in the hindgut with a large population of bacteria species (Table 1).
A system opened to the external environment
The microbiota is influenced by numerous factors: diet, microbiological quality of the feed, physiological stress, use of antibiotics and farming management practices – to name just a few.
A community in a relationship with the host
- A mutual relationship, or synbiosis, exists between the microbiota and the host: each individual benefits from the activity of the other.
- The microbiota acts on several digestive, metabolic and immune functions of the animal and can even mitigate the expression of some genes of the host.
The swine gut microbiota plays a key role in digestion and host defenses and, consequently, on health and performance. It is a complex microbial ecosystem, adapted to the diet, physiological factors, and site of the gut. This ecosystem tends to remain close to an equilibrium state but can be disturbed by different internal and external factors, such as diet, environment or farming practices.