A group of scientists from several research institutions — Clermont-Ferrand University (Université Clermont Auvergne [UCA]), INRA and Institut de l’Elevage in France and Ghent University in Belgium — and Lallemand Animal Nutrition published an in-depth review on postweaning piglet gut microbiota dysbiosis (microbial imbalance) in Trends in Microbiology.

First, the researchers reviewed the impact abrupt dietary and environmental changes during weaning had on piglets’ digestive microbiota, which can lead to enteric problems. Next, the researchers looked into the effects of non-antimicrobial alternatives that are currently evaluated to restore intestinal balance and allow better management of the weaning transition.

One of the conclusions of this extensive review is that, “among the available alternatives, probiotics seem to have the highest potential and could represent a safe opportunity to fight against postweaning dysbiosis and enteric infections in the swine industry.”

Additionally, the review evaluated in vitro models that have been designed to study the piglet microbiota and develop new feed additives, which is aligned with the European Union's 2010 directive to reduce the use of animals in research.

Reviewing non-antibiotic approaches in weaning piglets

Based on the need for non-antibiotic alternative strategies to restore microbial balance and control gastrointestinal infections associated with weaning transition in piglets, the authors reviewed studies that used several types of such approaches, including zinc oxide, organic acids, essential oils, prebiotics and probiotics.

Concerning the latter, they reviewed 12 probiotic studies (six in healthy piglets, and six in pathogen-challenged piglets) conducted with different types of bacteria or yeast probiotics. Conclusions indicate that lactic acid bacteria showed an increased abundance of Lactobacillus or Bifidobacterium spp. and a decrease in Escherichia coli in newly weaned piglets, highlighting a strain-dependent effect.

This led researchers to conclude that probiotics may have the greatest potential out of the various alternatives, "as they constitute the only feed additive that is efficient towards pathogenic strains in piglets. Although the underlying mechanisms are not fully understood, protection of piglets from postweaning infections by probiotics could notably occur through inhibition of pathogen growth and adhesion to intestinal mucosa, stimulation of the piglet immune system or modulation of the composition and activity of the resident microbiota.”

Piglet colon model

The same review also evaluated in vitro models of the piglet gut. Lallemand Animal Nutrition, together with academic partners from UMR MEDIS INRA-UCA, ANSES and Ploufragan University, recently contributed to the development of a new dynamic in vitro model of the piglet colon, called PigutIVM.

Until now, very few in vitro models of the pig gut existed, and none reproduced the piglet gut. Nevertheless, such a tool would be of high interest since the first weeks of life are a critical phase in the swine growing cycle.

PigutIVM is the first model of its kind that reproduces the anaerobic conditions of the colon maintained by microbial fermentations. It was used for the first time to assess the effects of antibiotics on the colonic microbiota of piglets and the effect of the probiotic yeast Saccharomyces cerevisiae var. boulardii CNCM I-1079.

The first results were published earlier this year, and the authors acknowledged the relevance of this model to replicate in vivo situations and its possible adaptation in future research projects to study piglet digestive dysbiosis.

Interestingly, the positive effect of S. cerevisiae var. boulardii CNCM I-1079 on the decrease in E. coli levels using PigutIVM confirmed previous in vivo evidence. A new project is ongoing with the same partners to improve the model and study various dysbiosis scenarios and new ways to mitigate it.

Dr. Mathieu Castex, research and development (R&D) director for Lallemand Animal Nutrition, said, “We are very proud to be involved in such advanced research into piglet microbiota. Over the past decades, ruminant researchers have focused a lot on the characterization and understanding of the rumen microflora, and experimental models (ranging) from in vitro fermenters to cannulated cows are common tools. When Lallemand started looking into swine microbiota more than 10 years ago, the level of knowledge was really low, and we acknowledged the fact that the swine microflora was underestimated.”

“Capitalizing on our advances in ruminant microflora, we focused major R&D efforts on piglets’ and sows’ digestive microflora. Development of the PigutIVM is one piece of the puzzle that will help us get a better understanding of probiotics’ and antimicrobials’ modes of action but also to look for new solutions -- a key in the actual context of antimicrobial reduction,” concluded Dr. Frédérique Chaucheyras-Durand, research manager at Lallemand.