Replacing antibiotics in meat production: Feeding pigs probiotics found to improve gut health, nutrient use, growth

The notion that antibiotics are a silver bullet for better health, both for humans and animals, is slowly losing its weight. In meat production, this is reflected in the current restrictions placed on antibiotic growth promoters. In line with the need for ideal alternatives to in-feed antibiotics to fill the gap, scientists from the Mississippi State University and the University of Manitoba published a paper outlining the current data and practices for probiotic use for swine production. The study, which appeared in the journal Animal Nutrition, targeted both manufacturers and researchers with the objective of better long-term product development.

The study highlighted the importance of healthy gut microbiota, even for pigs: The state of the microbiota of a pig is directly linked to its gut health, nutrient absorption, and overall body health. This is important, researchers wrote, as harmful organisms can enter the gastrointestinal system in normal environments and lead to negative health outcomes.

As with humans, the gut microbiota of pigs can also be manipulated through diet. Modern swine producers all over the world have used antibiotics to fulfill this function for a long time; however, recent studies note that the practice may have detrimental health outcomes in the long run. In particular, two concerns were noted: One is the presence of chemical residues from antibiotics, while the other is that these antibiotics are similar to those used in human medicine.

This is where probiotics come into play. Defined as “live microorganisms which, when administered in adequate amounts, confer a good health benefit on the host” by the World Health Organization, the word has come to mean all products that may contain bacterial cultures, yeast cells, or both that can trigger a response in the gut environment and improve the health of the host. Since its discovery in 1908, probiotics have been used both in human and animal food. In animals, probiotics are added in feeds to increase animal’s growth and boost its health status and resistance to disease. The authors list the current state of probiotic use. Currently, probiotic strains are selected based on its resistance to gastric acids and bile salts, ability to colonize the intestine, and its capacity to antagonize potential pathogens. (Related: Probiotics found to protect honey bees from toxic effects of pesticides.)

There are a number of commercial products that contain probiotic species of bacteria; in the study, authors classified it into four main categories: Single versus multi-species/strain probiotics, bacterial versus non-bacterial probiotics, spore-forming versus non-spore forming probiotics, and allochthonous versus autochthonous probiotics. This is where the difference between antibiotics and probiotics is most defined in swine: Antibiotics destroy bacteria indiscriminately, regardless if it is harmful or beneficial. Probiotics, on the other hand, allow the growth of benign bacteria and fends off potential pathogenic ones.

The authors also listed the functional mechanisms influenced by probiotics. These include the modulation of gut microbiota, modulation of immune responses, reduction of diarrhea and antitoxin effects, and modulation of nutrient digestibility, among others.

While there are have been multiple studies that report the positive effects of probiotics in gut flora, these suffered from “a lack of rigorous experimental design.” In the paper, the authors proffered the need to explain the benefits of probiotics further, as the evidence backing up these functional mechanisms is still incomplete.

Finally, the safety and risk of using probiotics were discussed. The authors noted that probiotic usage is generally regarded as safe for both human and animal use, but there is still a risk of an adverse reaction depending on a host’s susceptibility and physiological condition.

“Although generally considered safe, there is little evidence showing that probiotics are absolutely safe, and it has been generally agreed that ‘zero risk does not exist,'” the authors wrote in the report.

Overall, the authors believe that an increase in the knowledge of gut microbiota and the effects of probiotics could lead to innovations in the field and further improve sustainable – and profitable – swine manufacturing practices.

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