Bacterial Community Dynamics across the Gastrointestinal Tracts of Dairy Calves during Preweaning Development

Abstract

Microbial communities play critical roles in the gastrointestinal tracts (GIT) of preruminant calves by influencing performance and health. However, little is known about the establishment of microbial communities in the calf GIT or their dynamics during development. In this study, next-generation sequencing was used to assess changes in the bacterial communities of the rumen, jejunum, cecum, and colon in 26 crossbred calves at four developmental stages (7, 28, 49, and 63 days old). Alpha diversity differed among GIT regions with the lowest diversity and evenness in the jejunum, whereas no changes in alpha diversity were observed across developmental stage. Beta diversity analysis showed both region and age effects, with low numbers of operational taxonomic units (OTUs) shared between regions within a given age group or between ages in a given region. Taxonomic analysis revealed that several taxa coexisted in the rumen, jejunum, cecum, and colon but that their abundances differed considerably by GIT region and age. As calves aged, we observed lower abundances of taxa such as ,, and with higher abundances of and in the rumen. The jejunum also displayed taxonomic changes with increases in and taxa in older calves. In the lower gut, taxa such as, , and decreased and S24-7, , and increased as calves aged. These data support a model whereby early and successive colonization by bacteria occurs across the GIT of calves and provides insights into the temporal dynamics of the GIT microbiota of dairy calves during preweaning development. The gastrointestinal tracts (GIT) of ruminants, such as dairy cows, house complex microbial communities that contribute to their overall health and support their ability to produce milk. For example, the rumen microbiota converts feed into usable nutrients, while the jejunal microbiota provides access to protein. Thus, establishing a properly functioning GIT microbiota in dairy calves is critical to their productivity as adult cows. However, little is known about the establishment, maintenance, and dynamics of the calf GIT microbiota in early life. In this study, we evaluated the bacterial communities in the rumen, jejunum, cecum, and colon in dairy calves across preweaning development and show that they are highly variable early on in life before transitioning to a stable community. Understanding the dairy calf GIT microbiota has implications for ensuring proper health during early life and will aid in efforts to develop strategies for improving downstream production.

Repeated inoculation with fresh rumen fluid before or during weaning modulates the microbiota composition and co-occurrence of the rumen and colon of lambs

“…Several inoculum-predominant genera were significantly increased in the colon of the IDW lambs, but not the IBW lambs. These results are in general agreement with the successful colonization of some rumen bacteria in the colon of calves when they started consuming solid feed, and the number of taxa shared between the rumen and the colon increased as calves grew [61]. It is interesting to note that Veillonella was enriched in the colon of both the IBW and the IDW lambs in our study.…”

Dynamic Changes in Fecal Bacterial Microbiota of Dairy Cattle across the Production Line

“…2, 3, 4). These differences confirmed the earlier findings that the enteric microbiota in neonatal calves were different from the adult cows and the bacterial communities underwent a dramatic change during the development in early age (8,9,18). Intriguingly, bacteria from the samples in unit 2 displayed similar patterns with the communities from the adult cattle, predominately Firmicutes; but at the same time, they showed no significant difference from those in unit 1.…”

Residual feed intake divergence during the preweaning period is associated with unique hindgut microbiome and metabolome profiles in neonatal Holstein heifer calves

“…The greater abundance of carbohydrate-fermenting bacteria (i.e., Fusobacteria, Blautia, Lachnospiraceae, Proteobacteria, and Bacteroides) during the preweaning period in M-eff heifers suggests a better capacity for utilizing complex carbohydrates reaching the hindgut including cellulose, hemicellulose, resistant starch, and xylan [35][36][37]. This result is supported by previous studies in which digestibility of dry matter, organic matter, fiber, protein, and total digestible nutrients was greater in M-eff heifers [38].…”