Blue-green algae, also known as cyanobacteria, are microorganisms that are similar to both bacteria and plants. They produce poisonous algae blooms containing cyanotoxins, which are secondary metabolites that are highly toxic to cattle. Although there are several types of cyanotoxins, they primarily affect the cow’s liver (microcystins, nodularins and cylindrospermopsins) or nervous system (anatoxins and saxitoxins).
Algae blooms occur worldwide in fresh and brackish water bodies, usually nutrient-rich, calm waters such as that found in ponds and dugouts. They can also occur in small stagnant water puddles or water troughs. They develop in warm sunny weather with temperature conditions ranging from 50 to 86°F (10 to 30°C), high phosphorus concentrations (over 30 micrograms/L), and high water nitrogen content.
Cattle are poisoned through drinking from contaminated water, usually from the windward side of stagnant water sources. Symptoms of poisoning vary depending on the type of toxin ingested.
- Neurotoxic cyanotoxins: (associated with the nervous system) cause muscle tremors, decreased movement, difficulty breathing, convulsions, or in many cases sudden collapse and death.
- Hepatotoxic cyanotoxins: (associated with the liver) will cause weakness, bloody diarrhea, pale colored mucous membranes, mental derangement, and eventually death.