Evaluation of Bovine Rumen Microbial Populations Following Periods of Dietary Restriction and Subsequent Re-alimentation

Authors: Matthew S. McCabe, Paul Cormican, Kate Keogh, Aaron O’Connor, Eoin O’Hara, Rafael Alejandro Palladino, David A. Kenny and Sinead M. Waters 

Periodic feed restriction is used in cattle production to reduce feed costs, subsequently when normal feed levels are resumed; cattle typically display an accelerated growth phenomenon, known as compensatory growth (CG). Our objective was to examine microbial populations in rumen digesta following a period of dietary restriction and subsequent CG using Illumina Miseq Phylogenetic marker amplicon sequencing of DNA extracted from rumen contents. 60 Holstein Friesian bulls were fed either a restricted diet (125 days), following which they were fed ad libitum for a further 55 days or fed ad libitum for the entirety of the trial. Rumen digesta samples were collected at the end of each period. Following a period of restricted feeding a large increase in overall species diversity, as well as an increase in the relative abundance of Methanobrevibacter gottschalkii clade were observed. A large decrease in the relative abundance of an uncharacterised Succinivibrionaceae species was also evident. The increase in the Methanobrevibacter gottschalkii clade was strongly correlated (ρ=-0.72, P<1x10^-20) with the decrease in the Succinivibrionaceae species. Fifty five days of re-alimentation following previous dietary restriction, resulted in animals displaying CG, growing at 1.8 times that of their non-restricted counterparts. However although they displayed accelerated growth, their rumen microbes were not different to animals not restricted. This showed that the disruption caused by feed restriction did not have any long term effects on the rumen microbiome composition. Additionally, it also showed that the rumen prokaryotic microbiome was not associated with CG following 55 days of re-alimentation.