The safety of fermented milk as a feedback method to reduce diarrhoea in newborn piglets

Diarrhoea in newborn piglets represents a significant challenge to pig production. Controlled oral exposure, also known as "feedback", whereby sows are exposed at least two weeks before farrowing to pathogens that cause health problems in piglets, is a traditional method of diarrhoea prevention. One type of feedback involves fermenting cow's milk with faeces from piglets suffering from diarrhoea and administering it to sows before farrowing. The bacterial composition of the faecal inoculum and fermented milk was compared in this study, and the safety of administering the fermented milk to pregnant sows was evaluated. Using microbiota characterisation by 16S rRNA gene sequencing, the genera <i>Acetobacter</i>, <i>Lactobacillus</i> and <i>Lactococcus</i> formed the core microbiota of the fermented milk. However, <i>Clostridium perfringens</i> accounted for up to 33% of the total microbiota in some fermented milk samples. Interestingly, the drop in pH during the later stages of fermentation inactivated <i>C. perfringens</i> and the samples were thus enriched for inactivated <i>C. perfringens</i> antigen. Our findings contribute to a better understanding of the mode of action of fermented milk when used as a form of feedback.