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Circulating amino acids and biomarkers of metabolism and inflammation during the peripartal period in cows with different liver functionality index (LFI)
Objectives were to profile amino acids (AA) and biomarkers of inflammation during the peripartal period. Eighteen multiparous cows were used from -21 through 56 d around parturition. Cows were monitored for health status, milk yield, and dry matter intake. Body weight and body condition score (BCS) were measured every week. Blood samples were obtained twice weekly or daily from -10 to 10 d. Cows were ranked retrospectively in tertiles according to the liver functionality index (LFI), which includes three liver biomarkers of hepatic function: albumin, cholesterol, and total bilirubin. LFI measures the relevant changes in concentrations between 3 and 28 d, standardized with the optimal pattern of change for the 3 parameters obtained from healthy cows at the same stage of lactation. A high LFI (better liver function) is characterized by lower bilirubin and higher cholesterol and albumin, and the opposite is true for low LFI. Although DMI (16.8 kg/d) and BCS (2.45) did not differ (P > 0.05) due to LFI or the interaction, cows in the high (39.2 kg/d) and medium (34.8 kg/d) vs. low (30.8 kg/d) LFI had greater (P < 0.05) milk production. As expected, there was a significant interaction (P < 0.05) for the concentration of albumin, cholesterol, and bilirubin such that cows in low vs. high LFI had lower cholesterol and albumin but greater bilirubin namely after calving. There was no interaction or LFI effect (P > 0.05) for NEFA, hydroxybutyrate, and haptoglobin but concentrations increased (P < 0.05) after calving. The interaction (P = 0.06) effect observed for concentration of essential AA was due in part to greater values in high and medium LFI cows namely during d 7 through 14. A similar type of response resulted in a trend (P = 0.10) for an interaction in the concentration of branched-chain AA (BCAA). There was no LFI or interaction effect (P > 0.05) for concentration of Lys, which decreased (P < 0.05) markedly from -21 d to calving followed by a gradual increase to prepartal values by d 14. In contrast, concentration of Met decreased markedly between -21 d and calving but did not reach prepartal values until d 42. Results suggest some alterations in postpartal EAA and BCAA concentration such that cows with high vs. low LFI produce more milk and maintain greater concentrations of these AA.
Keywords: transition period, inflammation, immunometabolism