218 Effects of feeding a vitamin and mineral supplement and (or) an energy supplement on concentrations of amino acids in beef heifer serum and fetal fluids at d 83 of gestation

Abstract

Abstract Objectives were to evaluate effects of feeding vitamin and mineral (VTM) and (or) energy (NRG) supplements on concentrations of amino acids (AA) in heifer serum and allantoic (ALF) and amniotic (AMF) fluids at d 83 of gestation. Thirty-five crossbred Angus heifers (body weight = 359.5 ± 7.1 kg) were randomly assigned to one of four treatments (n = 8 or 9/group) in a 2 × 2 factorial arrangement with main effects of vitamin and mineral (NoVTM or VTM) and energy (NoNRG or NRG) supplements. Heifers were fed a basal total mixed ration once daily with VTM and NRG treatments top-dressed. The VTM treatment (113 g•heifer-1•d-1) was initiated 71 to 148 d before artificial insemination (AI). The NRG treatment was initiated at AI targeting gains of 0.28 kg/d for NoNRG and 0.79 kg/d for NRG. Serum, ALF, and AMF were collected at d 83 ± 0.27 of gestation and analyzed for concentrations of AA. In serum, a VTM × NRG interaction (P = 0.02) was observed for Glu, with greater concentrations for VTM-NoNRG than VTM-NRG. Concentrations of serum Cys, Met, and Trp were greater (P ≤ 0.03) for NRG than No-NRG. In ALF, concentrations of Glu were affected by a VTM × NRG interaction, where VTM-NRG was greater (P < 0.01) than all others. In ALF, VTM increased (P ≤ 0.05) concentrations of His, Asp, and 12 of the 14 neutral AA, whereas NRG increased (P ≤ 0.05) Arg, Cys, and Asp. In AMF, AA concentrations were not affected (P ≥ 0.10) by VTM, NRG, or their interaction. In conclusion, an increase in neutral AA concentration in ALF from beef heifers was observed at d 83 of gestation with VTM supplementation, suggesting effects on the mechanisms of AA uptake and balance between the maternal circulation and fetal fluid compartments.