Location: Livestock Issues Research
Title: Effect of citrus pulp on the viability of the probiotic Saccharomyces cerevisiae bouldarii (Levucell) and subsequent effects in presence of pathogens Authors
Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: November 27, 2012
Publication Date: N/A
Technical Abstract: The probiotic Saccharomyces cerevisiae subtype boulardii (i.e., Levucell) is commonly provided to weaned and nursing sows to promote intestinal health through limiting the colonization of pathogens. Recent research from our group identified that supplementation of this probiotic to feed containing the alternate carbohydrate citrus pulp reduced (P < 0.01) the average daily gain of newly weaned pigs challenged with the enteric bacterium Salmonella typhimurium. To determine the possible cause for this effect, an in vitro analysis was conducted on the interaction of Levucell in the presence or absence of citrus pulp in combination with exposure to Salmonella typhimurium. Viability was assessed for both Levucell and S. typhimurium in swine fecal growth medium supplemented with either 0% or 5% citrus pulp through viable plate counts for 48 hours. Citrus pulp reduced (P < 0.01) populations of Levucell by 1.5 log10 within 48 hours post-exposure, suggesting that citrus pulp may exhibit fungicidal activity. In co-cultures of S. typhimurium and Levucell, the populations of Levucell also decreased (P < 0.001) by 1.5 log10. However, when citrus pulp was included in the co-culture, greater reductions in the populations of S. typhimurium and Levucell were observed than in either single treatment. Therefore, it is possible that the decrease in average daily gain previously observed in swine was due to an increase in cytotoxin release by lysed S. typhimurium, which compounded the immune response to this pathogen. We have also identified that citrus pulp-induced lysis of Levucell provides protection to the growth of Escherichia coli O157:H7 by providing carbon sources that were utilized by this pathogen. Though future research is needed to determine if this effect occurs in vivo, these data strongly suggest caution should be exercised in providing citrus pulp to swine being fed diets supplemented with live yeast probiotics.