Plasma 3-methylindole and Blood 3-methyleneindolenine in Feedlot Cattle

Authors

  • Guy H. Loneragan Colorado State University, Ft. Collins, CO
  • Paul S. Morley Colorado State University, Ft. Collins, CO
  • John J. Wagner Continental Beef Research, Lamar, CO
  • Daniel H. Gould Colorado State University, Ft. Collins, CO
  • Gary S. Mason Colorado State University, Ft. Collins, CO
  • Garold S. Yost University of Utah, Salt Lake City, UT

DOI:

https://doi.org/10.21423/aabppro20015193

Keywords:

Bovine respiratory disease complex, Rumen-generated toxins, 3-methylindole, enzymes

Abstract

Bovine respiratory disease complex (BRD) results from an interaction of stressors, animal susceptibility and respiratory pathogens. Well known factors that increase the likelihood of BRD development include young animals, long transportation distances and dehydration. Rumen-generated toxins, such as 3-methylindole (3MI), may also be an important BRD-propagating factor.

Animals challenged with both bovine respiratory syncytial virus (BRSV) and 3MI developed more severe respiratory disease than animals challenged with BRSV or 3MI alone.1 Further, animals with greater serum 3MI concentrations at feedlot arrival had greater odds of being treated for respiratory disease than animals with lower serum 3MI.2

3-methylindole must be metabolized to induce toxicity. Enzymes responsible for the bioactivation of 3MI are P450s and prostaglandin H synthetase (PHS).3,5 These enzymes are found in high concentrations in the bovine Clara cells. The putative pneumotoxic metabolite of3MI thought responsible for 3MI-induced disease is 3-methyleneindolenine (3MEIN).4 Pulmonary injury is prevented if bioactivation of 3MI is blocked.

Cover image of the 34th Conference Proceedings: Four men on horseback lead a single cow through a pen. Yellow background.

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Published

2001-09-13

Issue

2001

Section

Research Summaries - Beef

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