| Ketosis is one of the most common transitional metabolic disorders in dairy cows,which has a significant impact on glucose and lipid metabolism,production performance and reproductive performance of postpartum dairy cows.The gut microbiota of dairy cows may provide a possibility to improve the prediction of susceptibility to ketosis,but there are few studies on the differences of hindgut microbiota in healthy and subclinical cows with ketosis.In this study,Holstein dairy cows with close parity(1-3 parity)in the late perinatal period were selected and divided into healthy group(7 days postpartum,BHBA<1.2mmol/L),and Subclinical ketosis group(7 days postpartum,1.2≤BHBA<3.0 mmol/L),and the recovery group(14 days postpartum,BHBA<1.2mmol/L)was selected from subclinical ketosis cows,with 9 cows in each group.The feed digestion,intestinal flora diversity and blood biochemical indexes of dairy cows in each group were analyzed and compared.The experimental results were as follows:Experiment 1:Study on the effect of postpartum blood ketone body level on feed digestion of dairy cows.The results showed as follows:compared with healthy group,the apparent digestibility of CP and EE in subclinical ketosis group was significantly decreased(P<0.05),and the apparent digestibility of NDF and ADF was extremely significantly decreased(P<0.01).Compared with subclinical ketosis group,the apparent digestibility of CP,EE and NDF in recovery group was increased,and the apparent digestibility of ADF was significantly increased(P<0.01).Experiment 2:Study on the effect of postpartum blood ketone body level on fecal flora of dairy cows.The results showed that at phyla level,Firmicutes,Bacteroidetes and Proteobacteria were the dominant phyla in feces of three groups.Compared with healthy group and recovery group,fecal abundance of Bacteroidetes in subclinical ketosis group was significantly decreased(P<0.05),while fecal abundance of Proteobacteria was significantly increased(P<0.05).Compared with healthy group,fecal Spirochaetes abundance in subclinical ketosis group and recovery group was significantly decreased(P<0.01).The fecal abundance of Euryarchaeota in subclinical ketosis group was significantly lower than that in healthy group(P<0.05).At the genus level,compared with the healthy group,the abundance of Solibacillus and Escherichia-Shigella in feces of cows in subclinical ketosis group was significantly increased(P<0.01),and the abundance of Acinetobacter was significantly increased(P<0.05).Compared with healthy group and recovery group,the fecal abundance of Ruminococcus-UCG-005 and Rikenellaceae RC9_gut_group in subclinical ketosis group was significantly decreased(P<0.01),the abundance of Ruminococcus-UCG-001 and Christensenellaceae_R-7_group was significantly decreased(P<0.05),while the abundance of Psychrobacillus was significantly increased(P<0.05).Experiment 3:Study on the influence of postpartum blood ketone body levels on blood biochemical indexes of dairy cows.The results showed that:compared with the healthy group and the recovery group,the free fatty acid(NEFA)concentration of the subclinical ketosis group was significantly higher(P<0.01),while the glucose(Glu)and triglyceride(TG)concentrations were extremely high(P<0.01).Compared with the cows in the healthy group,the serum potassium concentration and superoxide dismutase(SOD)activity of the subclinical ketosis group and the recovery group were extremely significantly decreased(P<0.01),while the alanine aminotransferase(ALT)activity was extremely significantly increased(P<0.01).High-density lipoprotein cholesterol(HDLC),immunoglobulin G(IgG)concentrations,and glutathione peroxidase(GSH-Px)activity were significantly lower in subclinical ketosis cows compared with healthy cows(P<0.05),while low-density lipoprotein cholesterol(LDLC)concentrations and alkaline phosphatase(ALP),glutamyl transpeptidase(GGT),aspartate aminotransferase(AST),malondialdehyde(MDA)activities were significantly elevated(P<0.05).In conclusion,compared with healthy cows,the apparent digestibility of each nutrient in feed of subclinical ketosis cows was significantly decreased.Compared with subclinical ketosis,the apparent digestibility of feed nutrients was increased by hemoketone recovery.The abundance of some fibre-degrading bacteria in feces of cows with subclinical ketosis was significantly decreased,while the abundance of some pathogenic bacteria was significantly increased.The abundance of Ruminococcus,Rikenellaceae_RC9_gut_group and Christensenellaceae_R-7_group decreased significantly,and the abundance of Solibacillus 1 and Acinetobacter increased significantly,which were the characteristics of subclinical ketosis of dairy cows.The lipid metabolism of cows with subclinical ketosis at 7 days postpartum was significantly enhanced,liver function was abnormal at 7 and 14 days postpartum and antioxidant capacity was significantly reduced. |
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