title: Development of Ruminal and Fecal Microbiomes Are Affected by Weaning But Not Weaning Strategy in Dairy Calves.
abstract: The nature of weaning, considered the most stressful and significant transition experienced by dairy calves, influences the ability of a calf to adapt to the dramatic dietary shift, and thus, can influence the severity of production losses through the weaning transition. However, the effects of various feeding strategies on the development of rumen or fecal microbiota across weaning are yet to be examined. Here we characterized the pre- and post-weaning ruminal and fecal microbiomes of Holstein dairy calves exposed to two different weaning strategies, gradual (step-down) or abrupt. We describe the shifts toward a mature ruminant state, a transition which is hastened by the introduction of the solid feeds initiating ruminal fermentation. Additionally, we discuss the predicted functional roles of these communities, which also appear to represent that of the mature gastrointestinal system prior to weaning, suggesting functional maturity. This assumed state of readiness also appeared to negate the effects of weaning strategy on ruminal and fecal microbiomes and therefore, we conclude that the shift in gastrointestinal microbiota may not account for the declines in gain and intakes observed in calves during an abrupt weaning.
authors.affiliation: Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton AB, Canada.
authors.forename: Sarah J
authors.initials: SJ
authors.lastname: Meale
authors.affiliation: Department of Animal Science, University of Manitoba, Winnipeg MB, Canada.
authors.forename: Shucong
authors.initials: S
authors.lastname: Li
authors.affiliation: Department of Animal Science, University of Manitoba, Winnipeg MB, Canada.
authors.forename: Paula
authors.initials: P
authors.lastname: Azevedo
authors.affiliation: Department of Animal Science, University of Manitoba, Winnipeg MB, Canada.
authors.forename: Hooman
authors.initials: H
authors.lastname: Derakhshani
authors.affiliation: Department of Animal Science, University of Manitoba, Winnipeg MB, Canada.
authors.forename: Jan C
authors.initials: JC
authors.lastname: Plaizier
authors.affiliation: Department of Animal Science, University of Manitoba, WinnipegMB, Canada; Department of Medical Microbiology, University of Manitoba, WinnipegMB, Canada.
authors.forename: Ehsan
authors.initials: E
authors.lastname: Khafipour
authors.affiliation: Department of Agricultural, Food and Nutritional Science, University of Alberta, EdmontonAB, Canada; Nutreco Canada Inc., GuelphON, Canada.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Steele
keywords: 16S rRNA gene sequencing; Holstein dairy calves; MiSeq Illumina sequencing; feces; microbiome; rumen; weaning