Blue-green algae toxicosis in cattle.

Twenty-four of 175 heifers died after ingesting water from a stock pond containing blue-green algae (genus Microcystis) in southern Colorado. Affected cattle were found dead or had signs of nervousness, and were recumbent, weak, anorectic, and hypersensitive to noise when first examined. All cattle died within 3 days after the onset of signs.