Livestock at Risk from Summer Algae Blooms

Hot Weather Raises Chances of Toxic Cyanobacteria Exposure

Summer’s hot and dry weather can lead to the development of harmful cyanobacteria, also known as blue-green algae, in water sources used by livestock.

These blooms often occur in stagnant ponds with high nutrient levels, especially nitrogen and phosphorus from manure and fertilizers.

Cyanobacteria can produce dangerous neurotoxins and liver toxins. Symptoms in animals range from weakness and trembling to respiratory distress and death.

Often, animals are found dead before symptoms are seen. “The hot, dry conditions projected for July are perfect for the production of cyanobacteria,” says Miranda Meehan, a livestock environmental stewardship specialist.

To reduce exposure, farmers are encouraged to test water sources following NDSU guidelines. Gloves should be worn when collecting samples to avoid human exposure.

Samples should include surface and subsurface water and be kept cool (not frozen) before being sent to a diagnostic lab.

Veterinarian Jake Galbreath advises producers to act quickly if poisoning is suspected. “A veterinarian can determine which samples would be appropriate for each situation,” says Galbreath.

Farmers can reduce cyanobacteria risks by following these steps -

• Apply nutrients at proper rates and times.

• Use buffer strips to limit runoff.

• Avoid direct livestock access to ponds.

• Pump water from deeper areas or alternative sources during hot spells.

Management practices like erosion control and strategic grazing also help reduce nutrient loads in water bodies.

Cyanobacteria are a serious summer concern, but with proactive water management and testing, the threat to livestock health can be greatly reduced.

For water testing and nutrient management resources, farmers are encouraged to contact local agricultural extension offices or visit NDSU's water quality page.