Abstract

Characterization of changes in hepatic expression of inflammation-associated genes during the peripartum period in multiparous Holstein cows using quantitative real time-PCR (RT-PCR)

N. A. Janovick, J. J. Loor, H. M. Dann, H. A. Lewin, and J. K. Drackley. University of Illinois, Urbana.

ADSA/ASAS/PSA Annual Joint Meeting, St. Louis, July 25-29, 2004

Dietary strategies in the dry period and early lactation might impact hepatic expression of genes associated with inflammatory responses, which in turn could impact metabolic adaptations to lactation.  The objective of this study was to characterize changes in hepatic expression of tumor necrosis factor-α (TNF-α), peroxisome proliferator activated receptor-γ (PPAR-γ), PPAR-α, and interleukin-6 (IL-6) during the dry period through 49 DIM in cows fed according to current NRC recommendations.  Five multiparous Holstein cows had ad libitum access to a far-off dry period diet (1.29 Mcal NEl/kg; 15.8% CP) from d -65 through -25 relative to parturition, followed by ad libitum access to a close-up diet (1.61 Mcal NEl/kg; 15.7% CP) from d -24 until parturition.  Cows were fed a common lactation diet (1.77 Mcal NEl/kg; 18.1% CP) from 1 through 49 DIM.  Liver biopsies were collected on d -65, -30, -14, +1, +14, +28, and +49 relative to calving and RNA was extracted with Trizol reagent.  Complementary DNA was made from 2 μg of total RNA and primers for RT-PCR were designed to yield amplicons <100 bp.  Relative copy number in PCR amplifications was measured using SYBRGreen I Dye fluorescence.  Bovine 18S rRNA was used as an internal standard for data normalization.  Day -65 relative to parturition was used as a baseline to compare relative changes in expression.  Relative to d -65, preliminary analysis of data using all cows showed that relative copy number of TNF-α was 1.85-fold greater (P = 0.05) on d + 1 relative to calving.  Fold changes on d -14 and +14 were not significant (P > 0.17). Relative copy number of PPAR-γ was 1.36, 1.94, or 1.83-fold greater on d -14, +1, and +14, respectively, however, these changes were not significant, P > 0.36.  Results showing increases in relative copy number for these two genes suggest that inflammatory or general stress responses occurred in the liver after parturition. Journal of Dairy Science, 88(Suppl. 1):195.