title: Metagenomic analysis of rumen microbial population in dairy heifers fed a high grain diet supplemented with dicarboxylic acids or polyphenols.
abstract: BACKGROUND
  The aim of this study was to investigate the effects of two feed supplements on rumen bacterial communities of heifers fed a high grain diet. Six Holstein-Friesian heifers received one of the following dietary treatments according to a Latin square design: no supplement (control, C), 60 g/day of fumarate-malate (organic acid, O) and 100 g/day of polyphenol-essential oil (P). Rumen fluid was analyzed to assess the microbial population using Illumina sequencing and quantitative real time PCR.
  
  
  RESULTS
  The P treatment had the highest number of observed species (P < 0.10), Chao1 index (P < 0.05), abundance based coverage estimated (ACE) (P < 0.05), and Fisher's alpha diversity (P < 0.10). The O treatment had intermediate values between C and P treatments with the exception of the Chao1 index. The PCoA with unweighted Unifrac distance showed a separation among dietary treatments (P = 0.09), above all between the C and P (P = 0.05). The O and P treatments showed a significant increase of the family Christenenellaceae and a decline of Prevotella brevis compared to C. Additionally, the P treatment enhanced the abundance of many taxa belonging to Bacteroidetes, Firmicutes and Tenericutes phyla due to a potential antimicrobial activity of flavonoids that increased competition among bacteria.
  
  
  CONCLUSIONS
  Organic acid and polyphenols significantly modified rumen bacterial populations during high-grain feeding in dairy heifers. In particular the polyphenol treatment increased the richness and diversity of rumen microbiota, which are usually high in conditions of physiological rumen pH and rumen function.
authors.affiliation: Department of Animal Medicine, Production and Health, University of Padova, Legnaro, PD, 35020, Italy. roberta.denardi@studenti.unipd.it.
authors.forename: Roberta
authors.initials: R
authors.lastname: De Nardi
authors.affiliation: Department of Animal Medicine, Production and Health, University of Padova, Legnaro, PD, 35020, Italy. giorgio.marchesini@unipd.it.
authors.forename: Giorgio
authors.initials: G
authors.lastname: Marchesini
authors.affiliation: Department of Animal Science, University of Manitoba, Winnipeg, MB, R3T 2 N2, Canada. shucong.li@umanitoba.ca.
authors.forename: Shucong
authors.initials: S
authors.lastname: Li
authors.affiliation: Department of Animal Science, University of Manitoba, Winnipeg, MB, R3T 2 N2, Canada. Ehsan.Khafipour@umanitoba.ca.
authors.forename: Ehsan
authors.initials: E
authors.lastname: Khafipour
authors.affiliation: Department of Animal Science, University of Manitoba, Winnipeg, MB, R3T 2 N2, Canada. Kees.Plaizier@umanitoba.ca.
authors.forename: Kees J C
authors.initials: KJ
authors.lastname: Plaizier
authors.affiliation: Department of Animal Medicine, Production and Health, University of Padova, Legnaro, PD, 35020, Italy. matteo.gianesella@unipd.it.
authors.forename: Matteo
authors.initials: M
authors.lastname: Gianesella
authors.affiliation: Department of Animal Medicine, Production and Health, University of Padova, Legnaro, PD, 35020, Italy. rebecca.ricci@unipd.it.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Ricci
authors.affiliation: Department of Animal Medicine, Production and Health, University of Padova, Legnaro, PD, 35020, Italy. igino.andrighetto@unipd.it.
authors.forename: Igino
authors.initials: I
authors.lastname: Andrighetto
authors.affiliation: Department of Animal Medicine, Production and Health, University of Padova, Legnaro, PD, 35020, Italy. severino.segato@unipd.it.
authors.forename: Severino
authors.initials: S
authors.lastname: Segato
mesh_terms: D000821:Animal Feed; D000818:Animals; D044822:Biodiversity; D002417:Cattle; D003998:Dicarboxylic Acids / Q000494:pharmacology*; D019587:Dietary Supplements; D002523:Edible Grain; D056186:Metagenomics; D064307:Microbiota / Q000187:drug effects*; D059808:Polyphenols / Q000494:pharmacology*; D012417:Rumen / Q000187:drug effects / Q000382:microbiology*
chemical_list: D003998:Dicarboxylic Acids; D059808:Polyphenols