The Influence of Ketosis on the Rectal Microbiome of Chinese Holstein Cows.

This study was conducted to analyze the changes in microbial populations of rectal content of dairy cattle with and without ketosis. The plasma β-hydroxybutyric acid (BHBA) levels of 350 cows were measured and twenty-two post-parturient dairy cows with BHBA levels >1.2 mmol/L were selected and diagnosed with ketosis (KET group). According to statistical pairing rule, 22 dairy cows with BHBA levels <0.60 mmol/l formed the control groups (CON group). The profile of the microbial community of the rectal content samples was detected using high-throughput sequencing analysis of hypervariable V4 region of microbe. The average effective sequences of each sample were 84983, ranging from 64090 to 94470. The Principal Co-ordinates Analysis (PCoA) showed that there were distinctly different clusters of the rectal microbial community between KET and CON cows. Beta diversity analysis was evaluated differences in samples of species complexity. At the phylum level, the percentage of Euryarchaeota of the KET cows was less than (P<0.05) in the CON group. At the genus level, the percentages of Ruminococcaceae-UGG-014, Methanobrevibacter, Erysipelotrichaceae-UGG-009, and Atopobium of the KET cows were less than (P<0.05) those found in the CON group. The percentage of Lachnospiraceae was greater (P<0.05) in KET cows compared with CON cows. Lachnospiraceae is related to butyrate production and an increased amount may be an important causative agent of ketosis in dairy cattle. Our findings give a complete picture of current knowledge of the population structure of the rectal microbial ecosystem between KET and CON cows and enhance our understanding about the rectal microbial ecology that may be useful in the prevention of ketosis. [ABSTRACT FROM AUTHOR]