By Kay Ledbetter
As the drought continues and temperatures remain above normal, cattle water is becoming a greater concern, especially after recent reports of cattle deaths in or around watering points, according to a Texas AgriLife Extension Service specialist.Dr. Ted McCollum, AgriLife Extension beef cattle specialist, said the location of the deceased cattle suggests the deaths could be associated with water consumption.
“Because little or no forage growth has occurred this year, the forage contains very low amounts of water,” McCollum said. “An average cow grazing green forage normally consumes about 30 to 70 pounds of water daily, or about 3.5 to 8.4 gallons, from the forage she grazes. “This year, as a result of no forage growth and a relatively low intake of dry forage, daily water consumption from grazed forage is probably around 3 to 5 pounds or 0.4 to 0.6 gallons.”
Couple low water intake from forage with the higher, stressful temperatures this summer, McCollum said, and intake of water from drinking sources takes on greater importance than "normal" years or years with high temperatures but with green forage. “The lack of water from forage is more important than we credit,” he said.
“How many people would think of going out to work for a few hours without a jug of water to drink from periodically? The water in the grazed forage is the cow's ‘jug of water’ that rehydrates her while she is out on the range or pasture.” High temperatures alone may not a problem, but hot temperatures in combination with lack of green grass as is the case this year, is a problem, McCollum said.
“The risk of heat stress is greater because we have high ambient temperatures combined with dry dead forage,” McCollum said. “The cow's ‘jug of water’ is relatively empty this year, and the risk of heat stress and water-related problems is greater.” He said water deprivation, water intoxication and water quality can all play a role. These three may act independently, but often they are interrelated.
Water deprivation occurs when cattle cannot consume an adequate amount of water, McCollum said. Water is a nutrient just as protein, vitamins and minerals. And reduced water intake can result in reduced performance. Water deprivation can be fatal or lead to circumstances that can be fatal.
He said many people immediately associate this with a situation in which a well cannot pump enough water to keep up with cattle needs, the breakdown of a well or watering system, or a pond or creek drying up. These certainly are of great concern, but water deprivation also can occur in circumstances when it is perceived there is an adequate amount of water available.
McCollum said cattle behavior may lead to water deprivation because they develop preferences for grazing sites and loafing areas. If more than one watering point is available, they may develop a preferred watering location in a pasture. So, a grazing area with multiple watering points may appear to have an adequate supply of water, he said. However, if cattle have a preferred site and that site breaks down, dries up or the water quality declines and reduces consumption, then water deprivation may occur.
Cattle with no familiarity of a grazing area also can suffer deprivation, McCollum said. “Do not assume cattle will find water. When cattle are moved to new pastures, take them to water and observe their consumption to determine if they are willing to consume the water,” he advised.
Water intoxication occurs when cattle over-consume water, McCollum said. It usually occurs following a period of reduced water consumption or increased water loss from the body. The cattle are dehydrated and consume an excessive amount of water. Electrolyte balance in the body is disrupted and water intoxication occurs, which can be fatal.
In cases of acute water intoxication, dead cattle will be found near the watering site, he said. Water intoxication typically follows water deprivation. So, a key to avoiding water intoxication is avoiding water deprivation. Limiting water intake when cattle are moved to a new water source may be next to impossible, McCollum said. If cattle are dehydrated, it may be worth the effort to allow them to drink, but find a way to limit the amount immediately consumed.
With the concern of water quality, the supply of water may be adequate but the cattle are deprived because they cannot or will not consume enough of the water, he said. Total dissolved solids and total soluble salts are two water quality measures that can lead to poor performance and possibly death. As the concentrations increase, water intake is reduced. Salinity of water limits intake just as salt in feeds can limit intake, McCollum said. Hence, water quality can lead to water deprivation.
Also, high consumption of sodium, calcium, magnesium salts and sulfates can lead to failure to thrive, and in some cases, can be fatal, he said. Nitrates in the water may also be of concern. “Coupled with reduced water intake, these issues can become even more of a concern,” he said. “Water quality can indirectly affect performance and health by reducing water consumption, which exacerbates heat stress and can lead to water intoxication once cattle locate or can access palatable water.”
Another problem McCollum pointed out is that hot sunny days and warm stagnant water may lead to blue-green algae blooms. Some species of blue-green algae are toxic, so consumption of the algae or the toxins from it can be fatal. As a result, dead animals may be found close to the watering site. Oftentimes, algae is concentrated on the downwind side of the pond as a result of wave action, he said. Dead rodents, birds or fish along the downwind side of the pond may indicate the presence of blue-green algae. Limiting access to the downwind side of the pond by cattle may reduce risk of toxicity.
Copper sulfate can be used to limit algae growth, but caution must be exercised because excess copper sulfate can lead to stream pollution and harm fish and plant life, McCollum said.
“Also, don't rule out toxic plants that may be present around watering locations. The immediate area around ponds and tank-overflows is disturbed, and the moisture profile in the soil is better than out in the pasture,” he said. “Even though drought conditions exist, disturbance and moisture are conducive to weed growth. Pigweed, kochia, Russian thistle, dock, buffalo burrs, etc. can grow in these areas, and they are green and may be attractive to cattle. If cattle deaths are occurring, see what has been grazed off around the watering area.”For more information on water quality for livestock the publication “Water quality: Its relationship to livestock” can be found at http://animalscience.tamu.edu/images/pdf/beef/beef-water-quality.pdf