Potential roles of colostrum microbiota in shaping calf gut microbiota and colostrum metabolites.

Colostrum provides vital nutrients and antibodies that are crucial for calf health and survival. It also contains microbes that may be vertically transmitted to calves and influence early gut microbiota development. These microbes in colostrum may also biologically function to produce unique metabolites that affect colostrum quality and calf growth. However, these colostrum components remain largely unexplored. The aim of this study was to identify colostrum-derived microbes capable of colonizing and persisting in the calf gut and to characterize colostrum metabolomics in relation to the colostrum microbiota. Colostrum samples were collected from 25 Holstein heifers, and fecal samples were collected from their individually housed Holstein-Angus crossbred offspring on d 4, 7, 14, and 30 after birth. Colostrum and fecal microbiota were analyzed using full-length 16S rRNA gene amplicon sequencing, whereas the untargeted metabolomics was performed using ultra-performance liquid chromatography MS. We identified 20% prevalent colostrum bacteria (15 species) were consistently detected in calf fecal samples across all time points, indicating their potential to colonize and persist in the early gut, although the relative abundance of these species in calf feces gradually decreased from d 4 to 30. Colostrum samples were classified into 3 distinct clusters based on the dominant species: