Prepartal energy intake alters blood polymorphonuclear leukocyte transcriptome during the peripartal period in Holstein cows

Using an Agilent microarray platform, the present study examined changes in the transcriptome of bovine polymorphonuclear leukocytes (PMNL) due to prepartal dietary intake. Twelve Holstein cows were fed a high-straw, control diet (CON; NEL = 1.34 Mcal/kg) or overfed a moderate-energy diet (OVE; NEL = 1.62 Mcal/kg) during the dry period. Blood for PMNL isolation and metabolite analysis was collected at -14 and +7 d relative to parturition. At an ANOVA false discovery rate (FDR) <0.05, energy intake (OVE vs. CON) influenced 1806 genes. Dynamic Impact Approach (DIA) bioinformatics analysis classified treatment effects on KEGG pathways, including: activated Oxidative Phosphorylation and Biosynthesis of Unsaturated Fatty Acids, and inhibited RNA Polymerase, Proteasome, and Toll-like Receptor Signaling Pathway. This analysis indicates that processes critical for energy metabolism and cellular and immune function were impacted with mixed results. However, overall interpretation of the transcriptome data agreed in part with literature documenting a potentially detrimental, chronic activation of PMNL in response to overfeeding. The widespread, transcriptome-level changes captured here confirm the importance of dietary energy adjustments around calving on the immune system. 8 cows were assigned to one of two groups which differed in dietary energy levels fed throughout the 45-d dry period. One group received at least 100% calculated NEL (CON; 1.34 Mcal/kg DM) from a diet high in wheat straw while the other received over 140% calculated NEL (OVE; 1.62 Mcal/kg DM) from a corn silage-based diet. Total RNA from PMNL isolated from coccygeal venous or arterial blood samples (~120 mL) collected in vacutainer tubes containing acid citrate dextrose (ACD Solution A; Fisher Scientific) on days -14 (±2) and +7 relative to parturition.