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

## TL;DR

This study explores how colostrum bacteria may colonize calf guts and influence early gut microbiota and metabolite profiles.

## Contribution

Identifies 15 colostrum bacterial species that persist in calf feces and links them to specific metabolites.

## Key findings

- 15 colostrum bacterial species were consistently detected in calf feces during the first month of life.
- Strong associations were found between colostrum bacteria and metabolites, including 4 species positively correlated with microbial-derived metabolites.
- Streptococcus uberis showed the most negative associations with metabolites among colostrum bacteria.

## Abstract

Summary: Colostrum is the first and essential meal in a calf's life; however, research investigating the microbial and metabolic profiles of colostrum in relation to calf gut microbiota remains limited. In this study, 15 bacterial species identified in colostrum were persistently detected in calf feces throughout the first month of life, indicating their potential to colonize the gut and influence the microbiota development of calves. Based on bacterial composition, colostrum samples were classified into 3 clusters, though no significant differences were observed in the metabolomic profiles between the clusters. Nevertheless, multiple associations were detected between colostrum bacteria and metabolites, including 4 of the 15 shared species that were positively correlated with microbial-derived metabolites. These microbial-metabolite interactions warrant further investigation to clarify their potential roles in colostrum quality and calf health. Created in BioRender.

Summary: Colostrum is the first and essential meal in a calf's life; however, research investigating the microbial and metabolic profiles of colostrum in relation to calf gut microbiota remains limited. In this study, 15 bacterial species identified in colostrum were persistently detected in calf feces throughout the first month of life, indicating their potential to colonize the gut and influence the microbiota development of calves. Based on bacterial composition, colostrum samples were classified into 3 clusters, though no significant differences were observed in the metabolomic profiles between the clusters. Nevertheless, multiple associations were detected between colostrum bacteria and metabolites, including 4 of the 15 shared species that were positively correlated with microbial-derived metabolites. These microbial-metabolite interactions warrant further investigation to clarify their potential roles in colostrum quality and calf health. Created in BioRender.

•Approximately 20% of colostrum bacteria persisted in the calf gut during the first month of life.•Colostrum metabolomic dynamics were not mainly driven by the colostrum microbial profile.•Strong associations were detected between colostrum bacteria and metabolites.•Streptococcus uberis exhibited the most negative associations with metabolites among colostrum bacteria.•Future work should validate the effect of microbial-associated colostrum metabolites on calves.

Approximately 20% of colostrum bacteria persisted in the calf gut during the first month of life.

Colostrum metabolomic dynamics were not mainly driven by the colostrum microbial profile.

Strong associations were detected between colostrum bacteria and metabolites.

Streptococcus uberis exhibited the most negative associations with metabolites among colostrum bacteria.

Future work should validate the effect of microbial-associated colostrum metabolites on calves.

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: Streptococcus thermophilus, Lactococcus lactis, and Comamonas testosteroni. Three colostrum samples from each cluster were selected as a focal group for the untargeted metabolomics analysis. We identified a total of 405 metabolites present in the colostrum samples. No significant differences in metabolomic profiles were observed among the 3 microbial clusters, indicating that colostrum microbiota were not the main drivers of metabolomic dynamics. However, 54 strong positive correlations were detected between bacterial species and metabolites, particularly between colostrum-calf feces shared species and microbial-derived metabolites. For example, 4-methylphenol was positively associated with Bacteroides fragilis, the most abundant bacterial species in calf feces on d 4. In addition, Streptococcus uberis, a pathogen associated with mastitis, exhibited the greatest number of strong negative correlations with metabolites. In conclusion, this study identified specific colostrum bacterial species with the potential to transmit and persist in the calf gut microbiota and to contribute to microbial metabolite production. Further research is warranted to evaluate the roles of these persistent microbes and their metabolites in shaping colostrum quality, calf growth, and health outcomes.