Abstract #T95

# T95
Coordinated responses of hepatic lipid-associated proteins in cows with high or low liver lipid content peripartum.
H. T. Holdorf*1, R. Caputo Oliveira1, R. S. Pralle1, H. M. White1, 1University of Wisconsin-Madison, Madison, WI.

Lipid associated proteins may allow for dynamic storage or utilization of liver triglyceride (lvTG). The objective of this study was to examine the coordinated response of liver lipases during the transition to lactation. Multiparous cows, representing a subset of a larger nutritional study (n = 40), were retrospectively grouped by maximum lvTG into a high (>15% DM; n = 6) or low (<15% DM; n = 10) group with no effect (P = 1.0) of original dietary treatment. Liver biopsies were collected at −28, −14, +1, +14, and +28 DRTC and LvTG was quantified. Protein abundance of abhydrolase domain containing 5 (ABHD5), hormone sensitive lipase (HSL), perilipin 1 (PLIN), patatin-like phospholipase domain containing 2 and 3 (PNPLA2, PNPLA3) was determined by Western blot analysis. Data were transformed as log10(abundance + 1), to achieve normal residuals. Data were analyzed for main effects of lvTG group, DRTC, and lvTG group x DRTC, and random effect of cow(lvTG group), dietary treatment, and repeated measures within cow using PROC GLIMMIX (SAS 9.4). Main effects were considered significant at P < 0.05 or marginal at P < 0.1. Means were separated by Tukey’s adjustment when interactions were P < 0.05. Abundance of ABHD5 tended to be greater (P = 0.09) at +28 compared with +1 DRTC and PNPLA2 was greater (P < 0.03) at +28 compared with −14 DRTC. An interaction of lvTG group × DRTC was detected (P < 0.05) for HSL and PLIN, but means could not be separated by Tukey’s post hoc analysis. There was an interaction (P < 0.01) of lvTG group × DRTC on the proportion of phosphorylated PLIN, relative to total PLIN (%PPLIN), with reduced (P < 0.03) abundance at +14 and +28 compared with prepartum time points in high lvTG cows. Additionally, %PPLIN tended to be greater (P = 0.07) in low lvTG cows, compared with high lvTG cows, at +28 DRTC. These data indicate that some hepatic proteins, namely ABHD5 and PNPLA2, are increased postpartum regardless of lvTG group while abundance of PLIN and HSL may reflect lvTG content. Shifts in the %PPLIN coincide with changes in lvTG and should be further examined for potential to mediate remobilization of stored lvTG.

Key Words: lipolysis, transition cow, fatty liver