Early life fecal microbiota transplantation in neonatal dairy calves promotes growth performance and alleviates inflammation and oxidative stress during weaning

This study aimed to evaluate the effects of early life fecal microbiota transplantation (FMT) on the health and performance of neonatal dairy calves. The donor was selected based on health and production records and fecal material testing negative for infectious pathogens. Sixteen healthy newborn Holstein calves were randomized to either a baseline nutritional program (CON) or 1×/d inoculations with 25 g of fecal donor material (FMT) mixed in the milk replacer (n = 8/TRT) from 8 to 12 days of age. Blood and fecal samples were collected weekly, and calves were weaned at 7 weeks of age. A TRT × Week interaction was observed in haptoglobin, which was reflected in a positive quadratic effect in FMT calves but not in CON. A trend for a TRT × Week interaction was observed in the liver function biomarker paraoxonase, which resulted in greater paraoxonase in FMT calves than CON at three weeks of age. Fecal microbial community analysis revealed a significant increase in the alpha-diversity between week 1 and week 5 for the FMT calves. These results suggest that early life FMT in neonatal calves has positive effects in mediating the inflammatory response and gut microbial maturation.