Abstract #M48

# M48
Characterization of peripartum circulating metabolites in cows with varying degrees of liver triglyceride accumulation.
C. R. Seely*1, H. T. Holdorf1, R. S. Pralle1, R. C. Oliveira1, J. L. Woolf1, M. R. Moede1, S. J. Erb1, H. M. White1, 1University of Wisconsin-Madison, Madison, WI.

Identification of circulating markers that reflect liver triglyceride (lvrTG) status would provide valuable insight when liver biopsies are not available. The objective of this study was to determine if metabolites related to energy balance and hepatic health would differ between cows with varying degrees of lvTG accumulation. Liver and blood samples were collected from multiparous Holstein cows (n = 37) at −14, +1, and +14 d relative to calving (DRTC) enrolled in 2 previously reported studies with 2 treatments (TRT) each. During the dry period, cows were fed a ration that met 100% (1 TRT; n = 13) or 120% (3 TRT; n = 7, 6, 11) of energy requirements to yield a range of postpartum lvTG. Postpartum rations were similar, except for 1 ration that included ammoniated lactate (n = 6). Cows were retrospectively grouped based on maximum lvTG% (DM basis) into 3 groups (TGgrp): high (lvTG = 30.3 ± 1.1%; n = 12), med (lvTG = 15.9 ± 1.06%; n = 13), or low (lvTG = 10.4 ± 1.1%; n = 12). Samples were analyzed for serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), albumin (alb), triglyceride (TG), β-hydroxybutyrate (BHB), and blood urea nitrogen (BUN), and plasma nonesterified fatty acids (NEFA) and glucose (glc). Data were analyzed in SAS (9.4) using Proc Mixed with fixed effects of TGgrp, DRTC, [h5] TGgrp × [SE6] DRTC, TGgrp × TRT and random effect of cow within TRT. Means were considered different at P < 0.05, and were separated by Tukey’s adjustment. Concentrations of AST, ALT, alb, BHB, BUN, glc, NEFA, and TG all changed over time (P < 0.01). Blood ALT, alb, and NEFA were different (P < 0.05) and glc tended to differ (P = 0.06) between TGgrp. Notably, NEFA was greater in the high group (P = 0.01, 0.45 ± 0.05 mmol/L) compared with the med and low groups (0.30 and 0.30 ± 0.06 mmol/L) and ALT was greater in the low group (P = 0.02, 20.2 ± 0.9 U/L) than the med and high groups (16.6 and 16.3 ± 1.0 U/L). A TGgrp by time interaction (P < 0.05) was observed for AST and BHB. It is clear that there are differences in circulating metabolites in cows with varying postpartum lvTG%, which may be useful in characterizing hepatic health.

Key Words: transition cow, biomarker, fatty liver