Protect livestock from blue-green algae this summer

By Scout Nelson

North Dakota farm and ag leaders are advising ranchers to protect livestock from the dangers of blue-green algae, scientifically known as cyanobacteria. These organisms accumulate in nutrient-rich water bodies, especially after heavy rainfall, and can appear as green, red, or yellow scum on the surface.

When ingested, they cause tremors, difficulty breathing, and even death in livestock. Preventive measures include managing nutrients to reduce runoff, fencing off contaminated areas, and using alternate water sources during the hot summer months. The North Dakota Ag Commission provides more tips on their website.

Cyanobacteria blooms result from excess nutrients, particularly nitrogen and phosphorus, commonly originating from fertilizer and manure runoff. The NDSU Extension publication “Environmental Implication of Excess Fertilizer and Manure on Water Quality” offers further information on this issue.

Blooms are more likely to occur during hot, sunny days in late summer and early autumn. Under favorable conditions, cyanobacteria can double their numbers in just one day. Rain, heavy winds, or cooler temperatures can disrupt these blooms, but they can persist for weeks under continuous favorable conditions.

These algae thrive in stagnant ponds with high nutrient levels, forming colonies that can appear green, red, or yellow. After dying, they often turn blue on the water’s surface or shoreline. Winds can concentrate these bacteria on the downwind side of water bodies, where livestock might drink.

North Dakota has several potentially poisonous cyanobacteria species, including Microcystis, Anabaena, Dolichospermum, Aphanizomenon, and Oscillatoria. These toxins affect the nervous system and liver, and are harmful to most livestock and wildlife, as well as humans.

Symptoms of poisoning in animals include weakness, staggering, difficulty breathing, convulsions, and death within 20 minutes of ingestion. Liver toxin symptoms include weakness, pale mucous membranes, mental derangement, bloody diarrhea, and death.

No antidotes exist for cyanobacteria poisoning, so awareness and prevention are critical. For human drinking water, the WHO guideline for microcystin-LR is 1 microgram per liter.

A veterinarian should confirm the cause of death. Reducing nutrient levels through proper fertilizer and manure management, reducing soil runoff, and implementing nutrient management plans are essential for long-term prevention.

Picture Credit: istock-dorin-s