摘要
Background:Ketosis in dairy cows is associated with body fat mobilization during the peripartal period.Sub-clinical and clinical ketosis arise more frequently in cows that are overfed energy during the entire dry(last 50 to 45 days prior to parturition)or close-up period(last^28 days prepartum).Methods:A retrospective analysis was performed on 12 cows from a larger cohort that were fed a higher-energy diet[1.54 Mcal/kg of dry matter(DM);35.9%of DM corn silage and 13%of DM ground corn]during the close-up dry period,of which 6 did not develop clinical ketosis(OVE,0.83 mmol/L plasma hydroxybutyrate;BHB)and 6 were diagnosed with clinical ketosis(KET,1.4 mmol/L BHB)during the first week postpartum.A whole-transcriptome bovine microarray(Agilent Technologies)and metabolomics(GC-MS,LC-MS;Metabolon~?Inc.)were used to perform transcript and metabolite profiling of liver tissue harvested at-10 days relative to parturition which allowed to establish potential associations between prepartal transcriptome/metabolome profiles and susceptibility to clinical ketosis postpartum.Results:Cows in KET had greater(P=0.01)overall body weight between-2 and 1 week around parturition,but similar body condition score than OVE.Although dry matter intake(DMI)did not differ prepartum,KET cows had lower(P<0.01)DMI and similar milk yield as OVE cows during the first week postpartum.Transcriptome analysis revealed a total of 3065 differentially expressed genes(DEG;P≤0.05)in KET.Metabolomics identified 15 out of 313 total biochemical compounds significantly affected(P≤0.10)in KET.Among those,greater concentrations(P≤0.06,+2.3-fold)of glycochenodeoxycholate in KET cows also have been detected in humans developing non-alcoholic fatty liver disease.Bioinformatics analysis using the Kyoto Encyclopedia of Genes and Genomes(KEGG)pathway database and the DEG revealed that,among the top 20 most-impacted metabolic pathway categories in KET,65%were overall downregulated.Those included’Metabolism of cofactors and vitamins’,’Biosynthesis of other secondary metabolites’,’Lipid’,’Carbohydrate’,and’Glycan biosynthesis and metabolism’.The lower relative concentration of glucose-6-phosphate and marked downregulation of fructose-1,6-bisphosphatase 2 and pyruvate dehydrogenase kinase 4 support a strong impairment in gluconeogenesis in prepartal liver of cows developing KET postpartum.Among the top 20 most-impacted non-metabolic pathways,85%were downregulated.Pathways such as’mTOR signalling’and’Insulin signalling’were among those.’Ribosome’,’Nucleotide excision repair’,and’Adherens junctions’were the only upregulated pathways in cows with KET.Conclusions:The combined data analyses revealed more extensive alterations of the prepartal liver transcriptome than metabolome in cows overfed energy and developing ketosis postpartum.The causative link between these tissue-level adaptations and onset of clinical ketosis needs to be studied further.
Background: Ketosis in dairy cows is associated with body fat mobilization during the peripartal period. Sub-clinical and clinical ketosis arise more frequently in cows that are overfed energy during the entire dry(last 50 to 45 days prior to parturition) or close-up period(last ～ 28 days prepartum).Methods: A retrospective analysis was performed on 12 cows from a larger cohort that were fed a higher-energy diet [1.54 Mcal/kg of dry matter(DM); 35.9% of DM corn silage and 13% of DM ground corn] during the close-up dry period, of which 6 did not develop clinical ketosis(OVE, 0.83 mmol/L plasma hydroxybutyrate; BHB) and 6 were diagnosed with clinical ketosis(KET, 1.4 mmol/L BHB) during the first week postpartum. A whole-transcriptome bovine microarray(Agilent Technologies) and metabolomics(GC-MS, LC-MS; Metabolon~? Inc.) were used to perform transcript and metabolite profiling of liver tissue harvested at-10 days relative to parturition which allowed to establish potential associations between prepartal transcriptome/metabolome profiles and susceptibility to clinical ketosis postpartum.Results: Cows in KET had greater(P = 0.01) overall body weight between-2 and 1 week around parturition, but similar body condition score than OVE. Although dry matter intake(DMI) did not differ prepartum, KET cows had lower(P < 0.01) DMI and similar milk yield as OVE cows during the first week postpartum. Transcriptome analysis revealed a total of 3065 differentially expressed genes(DEG; P ≤ 0.05) in KET. Metabolomics identified 15 out of 313 total biochemical compounds significantly affected(P ≤ 0.10) in KET. Among those, greater concentrations(P ≤ 0.06,+ 2.3-fold) of glycochenodeoxycholate in KET cows also have been detected in humans developing non-alcoholic fatty liver disease. Bioinformatics analysis using the Kyoto Encyclopedia of Genes and Genomes(KEGG) pathway database and the DEG revealed that, among the top 20 most-impacted metabolic pathway categories in KET, 65%were overall downregulated. Those included ’Metabolism of cofactors and vitamins’, ’Biosynthesis of other secondary metabolites’, ’Lipid’, ’Carbohydrate’, and ’Glycan biosynthesis and metabolism’. The lower relative concentration of glucose-6-phosphate and marked downregulation of fructose-1,6-bisphosphatase 2 and pyruvate dehydrogenase kinase 4 support a strong impairment in gluconeogenesis in prepartal liver of cows developing KET postpartum. Among the top 20 most-impacted non-metabolic pathways, 85% were downregulated. Pathways such as ’mTOR signalling’ and ’Insulin signalling’ were among those. ’Ribosome’, ’Nucleotide excision repair’, and’Adherens junctions’ were the only upregulated pathways in cows with KET.Conclusions: The combined data analyses revealed more extensive alterations of the prepartal liver transcriptome than metabolome in cows overfed energy and developing ketosis postpartum. The causative link between these tissue-level adaptations and onset of clinical ketosis needs to be studied further.
