Early-life fecal filtrate transplantation reduces mortality and post-weaning diarrhea in pigs reared without antibiotics
Background Enteritis is a leading cause of morbidity and mortality in young pigs. Based on a pilot study, we hypothesized that sow-derived fecal filtrate transplantation (FFT) to neonatal piglets would prevent diarrhea and enhance survival and growth until the post-weaning stage.   Methods FFT was administered orally once per day for the first six days after birth in 10 litters of 15 piglets each (n = 150) and a control group (CON) of the same size was administered placebo, leading to a total of 300 piglets included in the study. We assessed blood parameters, growth, diarrhea prevalence, survival, mucosal function, and colonic microbiota composition. Results There was substantial variation in plasma lactate levels at birth, with the smallest piglets having the highest levels. The baseline values for birth weight, lactate, and IgG were similar in the two groups. Body weights were higher for FFT piglets during the suckling period (days 6, 13, 20 and 27) but similar to CON piglets during the post-weaning period. The FFT group demonstrated a lower prevalence of post-weaning diarrhea (days 27, 32-37 and 41) and higher survival rates both before and after weaning (p < 0.05). Disaccharidase and aminopeptidase were lower in FFT piglets on day 41 (p < 0.05), whereas plasma concentration of intestinal fatty-acid binding protein was similar between the groups. Regardless of the method used, a significant difference in the colonic microbiota structure of FFT piglets was observed on both days, characterized by an enrichment of operational taxonomic units (OTU) and metagenome-assembled genomes (MAG) associated with beneficial bacterial families such as Oscillospiraceae and Lachnospiraceae. Resistome analysis revealed no significant effect of FFT on the overall abundance of resistance genes nor on the quantity of specific genes of relevance to public health.  Conclusion Oral FFT in early life significantly reduced post-weaning diarrhea and mortality resulting in significant changes in gut enzymatic activity and microbiota structure before and after weaning. The proposed FFT protocol offers a safe method to stabilize the gut and reduce diarrhea and reliance on antibiotics during this critical stage in the piglet's life.