Though temperature can play a big part in keeping cattle cool, many other factors can impact the summertime health of a herd.
Dr. Dave Sparks, Oklahoma State University Cooperative Extension veterinarian and food animal quality and health specialist, explains that heat stress can be exacerbated by several factors, such as humidity, lack of shade, poor water quality and forage content. Here are his top recommendations:
1. Humidity. Temperature levels that may not pose a threat at lower humidity levels can become dangerous as humidity increases, Sparks says. For example, consider a 90-degree Fahrenheit day. At 15% humidity, a watchful eye is needed; livestock drift into the "danger" level at 35% humidity, and are considered to be in an "emergency" situation at 65% humidity.
At 100 degrees Fahrenheit, 10% humidity pushes livestock into the danger zone, with 30% translating into an emergency situation.
2. Shade. While it's not easy to mitigate humidity, shade is a good option to keep cattle a bit cooler. Ruminant animals like cattle typically eat large quantities of forage, then rest and digest, Sparks says.
"The heat of fermentation produced in the rumen must be eliminated and a shady place to rest can aid this process," Sparks said. "As an experiment, place a thermometer in a shady place and another nearby but just outside the shade on a hot day; note the dramatic difference. Cattle cannot dissipate heat and their body temperature will rise when ambient temperature exceeds body temperature."
3. Water. An adequate supply of clean drinking water is important to helping livestock maintain a safe body temperature, Sparks notes.
"When cattle are allowed to stand, defecate and urinate in water sources, the palatability of the water can decline until the animals choose to limit their intake," Sparks says. "Research has shown when animals are fenced out and vegetation is allowed to grow to the water's edge, the water stays cooler as well as cleaner."
4. Forage Content. Endotoxins from fescue pastures have been known to cause a rise in body temperature of several degrees. Sparks notes this can make the difference between safe and critical conditions even when other factors are marginal.
"That is a prime reason why cattle on fescue pastures can often be seen seeking refuge in ponds or shade when cattle grazing adjoining non-fescue pastures are still actively consuming forage," Sparks says.
5. Activity Level. Sparks says activity level can be perhaps the greatest heat stress danger. He says working animals when environmental factors approach the danger zone is not recommended. Rather, work animals early in the morning before the day's heat buildup begins and after the previous day's heat buildup has dissipated.
Sparks warns against processing cattle in the evening, because it can take several hours for the animals' body temperatures to return to normal, even though ambient air temperatures might have declined into a more comfortable range.
And one last thing: Sparks says before cattle producers head out to work the cattle, they should check themselves. The same factors that are dangerous to cattle can be dangerous to people who handle livestock, he says.
News source: OSU