Physiology and Endocrinology

摘要

During transition period dairy cows have to deal with several stressfulevents e.g., change from a fiber-rich close-up diet to a high-concentratediet. Primiparous cows (PPC) might be more susceptible to these changesthan multiparous cows (MPC). The aim of the study was to investigate theblood microRNA (miRNA) profile of PPC and MPC before and duringfeeding of a high concentrate diet. Eight lactating Simmental cows (73± 25.4) DIM; 4 PPC, 4 MPC) were used for this study. Cows received abaseline diet (60% roughage; 40% concentrate) followed by a high concentratediet (HCD) for 4 weeks (40% roughage, 60% concentrate). Bloodwas collected during baseline diet, wk 1 and wk 4 of HCD. miRNAs wereisolated from plasma samples and sequenced using the CleanTag smallRNA library prep kit. Sequencing was performed on an Illumina NextSeq550. Reads were mapped against miRBase using miRDeep2. MiRNA rawread counts were processed using EdgeR and generalized linear modelsto perform differential expression analysis. P-values were adjusted formultiple testing using Benjamini-Hochberg false discovery rate. Overall,48 miRNAs were differently expressed in PPC and MPC (P < 0.05).During baseline, 16 miRNAs were differently expressed in PPC cowscompared with MPC (P < 0.05). While during wk 1 and 4 of HCD, 26and 10 miRNAs were differently expressed (P < 0.05), respectively. Differentialexpression was confirmed for a subset of miRNAs by RT-qPCR.Accordingly, the HCD increased the expression of bta-miRNA-122 by2.2-fold as well as the expression of bta-miR-30a-5p by 1.6-fold in wk 4(P < 0.05). These 2 miRNAs were as well affected by parity in wk 1 of theHCD as they were increased in PPC by 3.6-fold and 2.9-fold (P < 0.05),respectively. In addition, bta-miR-192 was increased by 1.5-fold, btamiR-194 by 1.4-fold and bta-miRNA-100 by 2.0-fold in PPC during wk1 of the HCD (P < 0.05). Furthermore, bta-miRNA-1246 was increasedby 2.1-fold in PPC (P < 0.05). In conclusion, HCD affected miRNAs associatedwith liver and mammary gland health in both PPC and MPCcows. However, other miRNAs associated with the gut and immune systemwere differently affected in PPC and MPC. Therefore, PPC mightneed special attention and might benefit from different management.