【摘要】 本试验旨在探究亚急性瘤胃酸中毒(subacute rumen acidosis,SARA)对泌乳奶牛血液生化指标和血浆代谢组的影响。试验选用8头装有永久性瘤胃瘘管的泌乳中期奶牛,随机分成对照组(CON)(n=4)和处理组(SARA)(n=4),CON组与SARA组分别饲喂精粗比为4∶6和6∶4的全混合日粮,试验周期为3周。于试验期每周最后一天晨饲后0、2、4、6、8和12 h进行瘤胃pH的测定,同时在pH测定当天晨饲后6 h采集颈静脉血样,用于血液生化指标和代谢组的分析。结果表明,与CON组相比,SARA组的瘤胃pH显著降低(P=0.002),两组干物质采食量没有显著差异(P=0.524)。血浆生化指标结果显示,与CON组比较,SARA组奶牛的β-羟丁酸浓度显著降低(P=0.007),甘油三酯浓度显著升高(P=0.014)。采用液相-质谱(LC-MS)联用技术对血浆进行代谢组学分析,主成分分析(PCA)和偏最小二乘法分析(PLS-DA)结果显示,SARA组奶牛血浆代谢物组成较CON组发生明显变化,两组间共检测到26种差异代谢物(VIP>1&FDR<0.05),与CON组相比,SARA组奶牛血浆中的7-酮脱氧胆酸、脱氧胆酸、胆酸、12-酮脱氧胆酸、12(13)Ep-9-KODE、12,13-DHOME和L-天冬酰胺代谢物含量显著升高(FDR<0.05),而十一烷二酸、十六烷二酸、9-HODE、血氧烷B3、PGE2、L-精氨酸、L-色氨酸、L-苏氨酸、异丁酰甘氨酸、异戊酰甘氨酸、马尿酸、4-羟基马尿酸和6-磷酸-2-脱氢-D-葡萄糖酸酯等代谢物含量显著降低(FDR<0.05)。综上,与CON组比较,SARA组奶牛的脂代谢、氨基酸代谢和糖代谢发生显著变化,这些物质可作为SARA潜在的生物标志物。更多还原

【Abstract】 This research explored the relationship between subacute ruminal acidosis(SARA)and blood metabolic changes in dairy cows.Eight ruminally cannulated Holstein cows in mid-lactation were randomly assigned to either a low-concentrate(40%)diet(CON)or a high-concentrate(60%)diet(SARA)for 3 weeks.On the last day of each week of the experimental period,ruminal pH was measured at 0,2,4,6,8 and 12 h after morning feeding,and blood samples for metabolomics analysis and determination of the biochemical indexes were obtained from the jugular vein at 6 h after morning feeding.It was found that,compared with the control group,ruminal pH was significantly reduced in the SARA group(P=0.002).No difference was observed in dry matter intake(DMI)between the two groups(P=0.524).The results for plasma biochemical indexes showed that cows fed the SARA diet had a lower plasma concentration of β-hydroxybutyrate(P=0.007),and a higher concentration of triglycerides(P=0.014).Plasma metabolomics profile was performed using liquid chromatography/mass spectrometry(LC/MS).Both principal component analysis(PCA) and partial least squares discriminant analysis(PLS-DA) showed a clear separation between the CON and SARA groups.By multivariate analysis,26 differential plasma metabolites were identified[variable importance in the projection(VIP)>1 and false discovery rate(FDR)<0.05].Compared with the CON group,in the SARA group,7-ketodeoxycholic acid,deoxycholic acid,cholic acid,12-ketodeoxycholic acid,12(13)Ep-9-KODE,12,13-DHOME and L-asparagine metabolites were significantly increased(FDR<0.05),while undecanedioic acid,hexadecanedioic acid,9-HODE,thromboxane B3,PGE2,L-arginine,Ltryptophan,L-threonine,isobutyrylglycine,isovalerylglycine,hippuric acid,4-hydroxyhippuric acid and 6-phospho-2-dehydro-D-gluconate were significantly reduced(FDR<0.05).Overall,compared with the CON group,SARA affected the lipid metabolism,amino acid metabolism and glucose metabolism of dairy cows.The identified differential metabolites may serve as potential biomarkers for SARA.更多还原