Bovine Mycotoxicosis Study Guide

Overview and Clinical Importance

Mycotoxicosis refers to diseases caused by ingestion of toxic secondary metabolites (mycotoxins) produced by fungi growing on grains, forages, and other feedstuffs. In cattle, mycotoxicosis represents a significant cause of multisystemic disease with effects ranging from subtle production losses to acute toxicity and death. Over 400 mycotoxins have been identified, but only a handful cause clinically significant disease in cattle.

The six major mycotoxins of concern in bovine practice include aflatoxins (hepatotoxic, carcinogenic), ergot alkaloids (vasoconstriction, gangrene), trichothecenes (DON and T-2 toxin causing immunosuppression), zearalenone (estrogenic effects), fumonisins (hepatotoxicity), and ochratoxin A (nephrotoxicity). Understanding these toxins is critical for NAVLE success as they frequently appear in questions involving multisystemic disease, production losses, and public health concerns.

Pathophysiology and Toxin Classification

Mycotoxins are produced by fungi primarily of genera Aspergillus, Fusarium, Penicillium, and Claviceps. Toxin production occurs in the field (pre-harvest) or during storage (post-harvest) depending on environmental conditions including temperature, moisture, and substrate availability.