Short communication: Postpartum plasma amino acid concentration in primi- and multiparous Holstein cows

Determination of 27 bovine plasma amino acids and metabolites using zwitterionic-hydrophilic interaction liquid chromatography coupled with isotope dilution electrospray ionization triple quadrupole liquid chromatography-mass spectrometry and the effect of deproteinization timing

“…The concentration of Orn in this study was 20.6 μ M on-site and 19.8 μ M in-lab, which are not within the range provided by Martineau et al (2017) of 30 to 82 μ M , although Chandler et al (2022) showed concentrations as low as 21.7 μ M . Concentrations of the other metabolites (urea, creatinine, 1MH, 3MH, carnosine) were also within the ranges found in the literature ( Fetter et al, 2021 ; Premi et al, 2021 ; Chandler et al, 2022 ), except for Hyp for which the present study had higher concentrations. Since Cys2 is bound to plasma proteins, the concentrations presented in this paper only reflect free Cys2 and not total Cys2.…”