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By Biomin, Austria
Starting during the seventies of the last century, after the discovery that young birds consuming faeces from adult birds were more resistant to Salmonella infections, probiotics in animal production have gained a lot of attention. A spectacular boost in research and overall market share of natural products for poultry was experienced at the end of the nineties due to the banning of antibiotics used as growth promoters in the European Union. Due to this regulation, classical diseases inherent to intensive poultry production systems that were once very well controlled with the use of low doses of antibiotics are now recovering momentum (necrotic enteritis).
Defined and undefined cultures
Undefined cultures are a collection of bacterial species. The numerically most predominant bacterial species are normally identified within these products. Undefined cultures tend to be a rapid solution to satisfy many markets. This is due to the lower cost of production when compared to defined cultures. If the selection process is carefully conducted and bacteria from healthy birds is collected and multiplied under appropriate conditions several key bacterial strains tend to remain stable and can be recovered after producing many batches of the original cultures.
One of the general concerns when using undefined probiotic cultures is the theoretical lack of consistency of the final product. It is likely that slight variations in the raw materials will change the rate in which different bacterial species multiply. This will probably result in a different performance of these probiotics under field conditions. We should always keep in mind that only a fraction of intestinal bacteria can be cultured using standard laboratory techniques and it is likely that the strains and or proportions of the strains contained in these products will change over time.
Probably the main factor that makes these products unacceptable in several markets is that hidden within the bulk of beneficial bacteria some pathogens could be propagating in low numbers. Favourable conditions, like application of the product in immune suppressed birds, could cause rapid propagation of these potential pathogens. In addition, if a defined list of bacteria is missing it is impossible to determine the risk of introducing antibiotic resistance genes into bacteria of the host’s intestinal tract, for example by plasmid transfer.
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