Prebiotics/Probiotics and Feed Additives

There is a lot of attention these days on the use of microbial supplements to improve aquaculture practices.  Something United-Tech has known for years.  The term ‘probiotic’ has loosely classified these supplements.  Probiotic comes from the Greek words pro (for) and biosis (life); Pro-life.  The use of probiotics then, is not to kill pathogenic organisms but to promote the proliferation of beneficial microorganisms.  The exact opposite of what an ‘antibiotic’ does.  There is some confusion over exactly what a probiotic is.  Some even confuse another term ‘prebiotic’ as being the same thing.  There have been lots of definitions out there but as the field is expanding, the industry is continually refining its definition. 

Probiotics are microbial supplements utilized to alter the biota of the gastrointestinal (GI) tract of the cultured species.  These active microorganisms have a positive effect on the host organism by modifying its GI biota.  These changes may improve the digestion of food and assimilation of nutrients and may limit potentially harmful microorganism populations.  Probiotic microorganisms work by adhering to the intestinal mucus blocking infection routes or displacing pathogens.  Benefits include: Enhanced of GI microflora and essential amino acids and vitamins they produce, increased absorption of vitamins and minerals, improved FCR, improved production statistics (harvest yields, ABW, survivability), improved effluent water quality, less disease incident, and elimination of antibiotic use.

Prebiotics can be classified as non-digestible supplements that beneficially affect the host by stimulating growth and/or activity of a limited number of health-promoting microorganisms (probiotics) in the GI tract.  These compounds also may even directly limit potentially pathogenic microorganisms.  Examples of prebiotics include various oligosaccharides such as those derived from chicory, palm kernel meal, or yeasts.  These saccharides can interfere with the binding of species like Salmonella, E. coli, and Vibrio to specific sugars - inhibiting their proliferation.  They help good microorganisms (probiotics) to outcompete these pathogenic species for food.

Arguably with aquaculture systems, application of potential prebiotic and probiotic materials to the water column will no doubt have an impact on the culture and this is where the definitions of prebiotic and probiotic become less clear.  Some include the improvement of water quality in culture systems since this removes the stressors like ammonia and nitrite and lessen the prevalence of pathogens like Vibrio or viral infections.  Plus microbial additions to the water column will no doubt make their way into the gut of the culture species.

Still for optimum prebiotic/probiotic effects BZT® products are introduced to the culture directly as feed supplements.  They can be added as a top dressing, applied in the field by the farmer or they can be added to the feed during processing.  Some spore-forming bacteria such as Bacillus can withstand the stresses of pelletization and are incorporated directly into the feed.  Another approach is to use powder-coating or post-coating processes which are far friendlier to the microorganisms being applied.  However, this surface coating process leaves bacteria subject to moisture (activation) during storage. 

In many cases farmers use BZT® as a top dressing to their feed while also applying directly to the water column.   This process allows maximum control and maximum efficacy of application.  Farmers know the same products that provide a direct impact on culture health also offer excellent control of water quality and solids buildup.  It is this two-pronged attack that makes BZT® application far superior to others.