Effects of prepartum dietary energy and lipid supplementation on hepatic transcriptome profiles in dairy cows during the transition period

transition period;transcriptome;Dairy cows

Khan, Muhammad

关键词: transition period;    transcriptome;    Dairy cows;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/45552/Muhammad_Khan.pdf?sequence=1&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

The transition period in dairy cows is the most crucial time for both cow health and dairy management. Three experiments were conducted on transition dairy cows to evaluate the effects of prepartum overfeeding and lipid supplementation around parturition on hepatic mRNA expression using qPCR and microarray techniques. In the first experiment, we examined the expression of 44 genes associated with PPARα target genes including fatty acid oxidation, TAG metabolism and storage, potential related nuclear receptors (NRs) and FGF21 modulating GH/IGF signaling in cows (n = 6/diet) assigned to a control (CON; NEL = 1.34 Mcal/kg DM) or moderate-energy (OVE; NEL = 1.62 Mcal/kg DM) diet during the entire dry period. All cows were fed a common lactation diet (NEL = 1.69 Mcal/kg DM) postcalving. Percutaneous liver biopsies were collected at -14, 7, 14, and 30 days relative to parturition (DIM) for transcript profiling via quantitative PCR. Estimated prepartal energy balance (EBAL) was greater (~159% vs. 102%, P<0.05) in OVE vs. CON, but during the first wk postpartum cows fed OVE prepartum were in more negative EBAL. Prior to calving, CON cows had greater (P < 0.05) serum FGF21, which corresponded with greater (P < 0.05) liver FGF21 expression. Concentration of FGF21 decreased (P < 0.05) gradually postpartum regardless of diet. Along with more severe negative EBAL, cows fed OVE vs. CON prepartum had greater (P < 0.05) postpartal concentrations of NEFA, BHBA, and GH in serum and liver triglyceride. Those data agreed with greater expression of ACOX1, CPT1A, ACADVL, HMGCS2, FGF21, and ANGPTL4 in OVE vs. CON at 7-14 DIM. Despite the gradual increase in serum GH after calving, at 7-14 DIM liver from cows fed OVE prepartum had greater (P < 0.05) IGFALS potentially to counteract the temporal decrease in hepatic GHR, STAT5ab, and IGF-1. Our results revealed transcriptional adaptations in liver resulting from the link between prepartal energy overfeeding and postpartal negative EBAL leading to greater serum NEFA. . Transcriptional changes encompassed not only LCFA oxidation and GH signaling but also hepatokine production.In the second experiment, we examined blood metabolites and expression of 58 genes related to inflammation and ER stress in the same cows assigned (n = 6/diet) to CON or OVE diets during the entire dry period. All cows were fed a common lactation diet (NEL = 1.69 Mcal/kg) postpartum. Blood was collected on d (± 3) -14, -5, -2, -1, 0, 1, 2, 5, 7, 10, 14 and 21 relative to parturition. Percutaneous liver tissue biopsies were harvested at -14, 7, 14, and 30 d relative to parturition for transcript profiling via quantitative PCR. Estimated prepartal energy balance (EBAL) was greater (P < 0.05) for OVE and averaged 159% of requirements compared with 102% in CON. However, EBAL during the first week postpartum was lower in OVE (83% vs. 89% of requirements). After parturition the concentrations of ceruloplasmin, creatinine, bilirubin and reactive oxygen metabolites (ROM) were greater (Diet × Time; P < 0.05) in OVE.Around calving the expression of ER and oxidative stress indicator genes XBP1, PERK, GRP94 and HSP40 was lower in OVE than CON but TRB3, HSPA1A, HSPA1B and CREB3L3 had greater (Diet × Time; P < 0.05) expression in OVE. Expression postpartum of the inflammatory genes NFKB1, RELA, CHUK, MYD88, TNF, SAA3, and PTX3 increased (Diet × Time; P < 0.05) in OVE. Genes associated with cell growth (mTOR, RPTOR, AKT3, TP53) also had greater (Diet × Time; P < 0.05) expression in OVE after parturition. Overall, results indicated that postpartal negative EBAL induced by prepartal OVE was associated with hepatic pro-inflammatory and pro-stress upregulation. In the third experiment, we used a microarray platform to determineexpression of the hepatic transcriptome in dairy cows (n = 6/diet) fed no supplemental lipid (control) or fed supplemental lipid from either Energy Booster 100 (a mixture of primarily saturated free fatty acids, mainly 16:0 and 18:0) or fish oil. Treatment diets were fed from -21 d until 10 d relative to parturition. The doses of lipid used were 250 g/d prepartum and 1% of the previous day’s feed intake postpartum. Percutaneous liver biopsies were harvested at -14, 1, and 14 d relative to parturition. A 13,257 bovine oligonucleotide (70-mers) array was used for transcript profiling. Pre- and postpartum feed intake, milk production, and body condition score were not affected by lipid supplementation. Blood NEFA (P = 0.06) and BHBA (P < 0.05) were lower postpartum in cows fed either lipid source but postpartal liver triacylglycerol did not differ in these cows (ca. 4% wet weight) relative to controls (4.5%). Liver transcriptome analysis by microarray revealed a list of differentially expressed genes (DEGs) within diet and time comparisons. The number of DEG was greater at day 1 and day 14, and the contrast of EB100 vs. FO at d 14 had the highest number of DEGs within diet comparisons. Within time comparisons, feeding fish oil resulted in a greater number of DEGs and the effect was strongest at day -14. Further computational and bioinformatics analysis by KEGG pathways using DIA indicated highly impacted metabolic pathways in both diet and time comparisons. Carbohydrate and lipid metabolism were the pathways most impacted by feeding fish oil and EB100. Also, cell communication, immune system, endocrine system and nervous system of KEGG pathways were impacted among all comparisons. Gene ontology functional analysis of DAVID by DIA also uncovered the most impacted pathways of growth and cellular component organization in the biological processes (BP) category, biological adhesion and multicellular organismal process in the molecular functions (MF) category, and membrane–enclosed lumen and organelle part in the cellular components (CC) category. Results from this experiment showed that feeding saturated (EB100) or unsaturated (fish oil) sources of fatty acids in transition cows induce strong changes in gene expression to control metabolism and other biological processes.