Amino Acids

, Volume 43, Issue 5, pp 2165–2177

Effects of rumen-protected methionine on plasma amino acid concentrations during a period of weight loss for late gestating beef heifers

  • Richard C. Waterman
  • Valerie L. Ujazdowski
  • Mark K. Petersen
Original Article

DOI: 10.1007/s00726-012-1301-3

Cite this article as:
Waterman, R.C., Ujazdowski, V.L. & Petersen, M.K. Amino Acids (2012) 43: 2165. doi:10.1007/s00726-012-1301-3


This study determined changes in plasma amino acid concentration in late-gestating (beginning 58 ± 1.02 days prior to calving), primiparous, winter-grazing range heifers receiving wheat middling-based supplement without (CON) or with rumen-protected methionine (MET) to provide 15 g dl-MET each day. Plasma was collected on days −2 and 0 (start of MET supplementation just prior to individually receiving supplement at 0700 hours). Plasma was sampled again on days 40, 42 and 44 prior to supplementation at 0700 and 1100 hours (4 h after receiving daily supplement). Data were analyzed with cow as the experimental unit. Continuous variables were analyzed by the main effects of treatment, date, or time and their interaction when appropriate. Comparable BW (P = 0.32) and BCS (P = 0.83) over the 44-day metabolism trial were found between both CON- and MET-fed heifers. MET-supplemented heifers had greater (P < 0.01) plasma concentrations of methionine indicating that the rumen-protection technology successfully delivered methionine to the small intestine. Supplementation with rumen-protected dl-MET caused a significant supplement × date interaction for glutamine (P = 0.03), glycine (P = 0.02), methionine (P < 0.01), and serine (P = 0.05). In addition, trends for supplement × date interactions were detected for leucine (P = 0.07), threonine (P = 0.09), valine (P = 0.08), total amino acids (TAA; P = 0.08), non essential amino acids (NEAA; P = 0.08), branched chain amino acids (BCAA; P = 0.08), and glucogenic amino acids (GLUCO; P = 0.08). These results suggest that the BCAA (leucine and valine) were utilized more efficiently with MET supplemented heifers compared to CON supplemented heifers. Plasma AA concentrations for glutamic acid (P < 0.01), histidine (P = 0.01), tyrosine (P < 0.01), and EAA (P < 0.01), all decreased throughout the study. These results further confirm methionine is a limiting amino acid in forage fed late-gestating heifers and further suggests the limitation when grazing dormant range forages as shown by improved utilization of other plasma amino acids when supplemental methionine was provided.


Amino acids Primiparous heifers Rumen-protected methionine 



Amino acids


Branch-chain amino acids


Body condition score


Body weight


Crude protein


Dry matter




Essential amino acids


Glucogenic amino acids


In situ neutral detergent fiber disappearance


Ketogenic amino acids


Livestock and range research laboratory


Mepron® M85


Neutral detergent fiber


Non essential amino acids


Organic matter


Total amino acids

Copyright information

© Springer-Verlag (outside the USA) 2012

Authors and Affiliations

  • Richard C. Waterman
    • 1
  • Valerie L. Ujazdowski
    • 2
  • Mark K. Petersen
    • 1
  1. 1.Fort Keogh Livestock and Range Research LaboratoryUnited States Department of Agriculture, Agricultural Research ServiceMiles CityUSA
  2. 2.School of Veterinary MedicineUniversity of WisconsinMadisonUSA

Personalised recommendations