Midway Extension District, Livestock Production

Blue-Green Algae

With the continued use of ponds and streams as a main water source during the grazing season, it is increasingly important to know the water quality our livestock is consuming. So what is blue-green algae?

Blue-green algae are actually bacteria named cyanobacteria. They can cause problems in many parts of the United States during hot weather. Occasionally, blue-green algae multiply rapidly and form blooms that look like scum on the water’s surface- often changing the water’s color to:

  • bright green,
  • blue-green or gray
  • occasionally red or brown

The research to date shows that toxin levels in a pond can be very different across different areas of the pond, so it is necessary to sample water from multiple places. As a general rule, if toxin levels are found in any sample, it is best to consider the entire pond to be a risky water source.

If blue-green algae toxins are found, livestock producers who are relying on the pond as a water source have a few options:

  1. Provide an additional water source for livestock.
  2. Move them off the pasture with the affected pond.

It is possible to kill the blue-green algae with several compounds, including copper sulfate. However, there are problems when utilizing this strategy. As blue-green algae die, they release toxin that will spread throughout the pond; copper sulfate will also kill competing organisms such as green algae, which keep blue-green populations lower. In addition, the higher level of copper in the pond water is toxic for sheep and some other animals- but considered safe for cattle.

Another strategy is to spread wheat or barley stray in a thin layer across the surface of the pond to prevent the algae from having the direct sunlight they need to survive and multiply. This strategy had the advantage of not using any toxic compounds, but the straw will need to be replaced as it sinks.

An affected pond can be a risk to cattle anywhere from a few days to several months; it is difficult to predict how long the risk will last in any given situation. In general, cool, cloudy and windy weather will reduce the amount of time that the problem lasts. Before allowing cattle to drink water from a pond that had a blue-green algae bloom, it is recommended that you send water samples into the lab for appropriate analysis to be certain the toxins are no longer present.

To summarize, making sure that cattle have access to plenty of good-quality water is one of the most important things we as producers must do for our herds. Insufficient space for animals to drink low flow rate, low storage capacity, high mineral or toxin content and unfamiliar taste can discourage water consumption to a point that feed intake is reduced or cause severe health problems.  It is always recommended to test your ponds and drinkers, but if you see the algae changing colors throughout the summer stop by the Extension Office and pick up a water test kit.

For more information about livestock and livestock water topics contact the Midway District Extension office or call (785)483-3157 or (785)472-4442. Dusti Lynne Betts serves as the Midway Extension District Livestock Production Agent. All Kansas Extension education programs and materials are available to all individuals without discrimination on the basis of race, color, national origin, sex, age, or handicap.

 

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