Short communication: Free fatty acid receptors FFAR1 and FFAR2 during the peripartal period in liver of dairy cows grouped by their postpartum plasma β-hydroxybutyrate concentrations

Free fatty acid receptors (FFAR) play significant roles in various physiological processes, including energy metabolism, through interaction with their ligands, fatty acids. To determine whether the receptors FFAR1 and FFAR2 are involved in the regulation of liver metabolism during the peripartal period, we selected 13 German Holstein multiparous dairy cows and grouped them as high β-hydroxybutyrate (H-BHB; n = 8) or low β-hydroxybutyrate (L-BHB; n = 5) according to their individual maximum plasma BHB concentration observed within wk 2 or 3 postpartum (H-BHB: >1 mmol/L and L-BHB: <0.77 mmol/L). The selected cows had a milk yield of more than 10,000 kg/305 d during a previous lactation. The cows were fed a total mixed ration according to their requirements during the far-off dry period [5.9 MJ of net energy for lactation (NEL)/kg of dry matter (DM), crude protein (CP) 126 g/kg of DM], close-up dry period (6.5 MJ of NEL/kg of DM, CP 137 g/kg of DM), and lactation (7 MJ of NEL/kg of DM, CP 163 g/kg of DM). Blood samples were taken weekly, from d −34 to d 40 relative to parturition. Liver biopsies were taken on d −34, −17, 3, 18, and 30 relative to parturition and at slaughter (d 40). The protein abundance of FFAR1 was lower during the whole peripartal period in the H-BHB group. The abundance of FFAR2 increased over time and tended to be higher in H-BHB cows. The abundance of FFAR1 might be associated with imbalances of liver metabolism in peripartal dairy cows.