Effects of Intramammary Antimicrobial Treatment on the Milk Microbiota Composition in Mild Clinical Bovine Mastitis Caused by Gram-Positive Bacteria

Mayu Hayashi; Yasunori Shinozuka; Tomomi Kurumisawa; Takuya Yagisawa; Nagomu Suenaga; Yuko Shimizu; Naoki Suzuki; Kazuhiro Kawai

doi:10.3390/ani13040713

Effects of Intramammary Antimicrobial Treatment on the Milk Microbiota Composition in Mild Clinical Bovine Mastitis Caused by Gram-Positive Bacteria

Animals (Basel). 2023 Feb 17;13(4):713. doi: 10.3390/ani13040713.

Authors

Mayu Hayashi¹, Yasunori Shinozuka^{1

2}, Tomomi Kurumisawa¹, Takuya Yagisawa³, Nagomu Suenaga¹, Yuko Shimizu¹, Naoki Suzuki⁴, Kazuhiro Kawai^{1

2}

Affiliations

¹ School of Veterinary Medicine, Azabu University, 1-17-71 Fuchinobe, Sagamihara 252-5201, Japan.
² Mastitis Research Center, Azabu University, 1-17-71 Fuchinobe, Sagamihara 252-5201, Japan.
³ Hokkaido Agriculture Mutual Aid Association, 4-1-1, Sapporo 060-0004, Japan.
⁴ Graduate School of Integrated Sciences for Life, Hiroshima University, 1-4-4 Kagamiyama, Higashi-Hiroshima 739-8528, Japan.

Abstract

The purpose of this study was to clarify the effects of antimicrobial treatment for mild mastitis caused by Gram-positive bacteria on the milk microbiota in dairy cattle. Sixteen quarters of sixteen cows with mild clinical mastitis from the same herd were included in the study. On the day of onset (day 0), the cows were randomly allocated to a no-treatment (NT; n = 10) group or an intramammary antimicrobial treatment (AMT) group that received AMT starting on day 0 (AMT-AMT group; n = 6). The next day (day 1), the cows in the NT group were randomly allocated into an NT group (NT-NT group; n = 3) that received no treatment or an AMT group that received AMT starting on day 1 (NT-AMT group; n = 7). Milk samples were collected on days 0, 1, 3 and 7, and the milk microbiota of each sample was comprehensively analyzed via 16S rRNA gene amplicon sequencing of the milk DNA. During the treatment period, the milk microbiota of the NT-NT group did not change, but those of the NT-AMT and AMT-AMT groups changed significantly on days three and seven. Thus, the use of antimicrobials for mild mastitis caused by Gram-positive bacteria changes the milk microbiota composition.

Keywords: 16S rRNA-based metagenomic analysis; gram-positive bacteria; intramammary antimicrobial treatment; mastitis; milk microbiota.

Grants and funding

This research received external funding by Grants-in-Aid for the Promotion of the Livestock Industry from Japan Racing Association Grant Number R4-117.