A probiotic or direct-fed microbial (DFM) can be defined as a live organism that has beneficial health effects to the host by modulating or improving the intestinal microbial balance. Achieving gut health – and the subsequent performance benefits that come with it – is largely dependent on establishing a balance in the gut microbiota in which beneficial bacteria, such as Bacillus spp., keep non-beneficial bacteria under control. There are many unique species of Bacillus with numerous subtypes (or strains) within each species. The effectiveness of each strain against a specific pathogen varies considerably. Therefore, in the development of a probiotic as a supplement for animal diets, a multi-strain solution certainly has its benefits as this provides better coverage against diverse non-beneficial microbial populations. Not all DFM are created equal and, ultimately, results achieved by including a DFM in your ration may vary considerably.
Enviva® PRO is a three-strain Bacillus amyloliquefaciens that provides broad control and growth inhibition of highly diverse pathogenic populations in the gastrointestinal tract (GIT), including avian pathogenic Escherichia coli (APEC). Selecting and including a multi-strain solution provides better coverage simply because, if one of the strains is not as effective in its inhibition action against APEC, there are two other strains that can compensate for this. Different strains of Bacillus spp. also exhibit different modes of action in the GIT and using more than one strain facilitates the benefit of multiple modes of action:
- An effective probiotic works by promoting or supporting the growth of beneficial gut bacteria, while reducing the number of enteric pathogenic bacteria by means of competitive exclusion. This is done by increasing the number of beneficial bacteria, which then compete with the non-beneficial bacteria.
- Reducing the number of non-beneficial enteric bacteria can also happen by the secretion of anti-microbials.
- A probiotic can also work by modulating the intestinal immune system by reacting with receptors located on the epithelial surface, which leads to downstream signalling cascades such as the activation of innate phagocytic scavenger cells. These cells have the role of ingesting any foreign material such as microorganisms that may have translocated through the gut barrier.
- Another way the probiotic can be beneficial is by reducing inflammation caused by a disease challenge.
- Published data have shown that the probiotic has benefits by improving gut structure by means of increasing villi height and consequently improving nutrient absorption.
Each strain of Bacillus has its own characteristic due to the secretion of different enzymes and antimicrobials in different concentrations. The strain that is best suited for the host animal will depend on what one wants to achieve.
Read more about probiotics and antibiotic resistance in the next article in this series.
Anneleen Swanepoel is a poultry layer specialist at Chemuniqué. She holds a bachelor's degree in animal science from the University of Pretoria, as well as a master's degree in aquaculture from Auburn University in the United States.