Heat Stress Can Cause Cattle Loss

Proper Preparation During Hot Summer Days Can Help Prevent Cattle Loss

Jennifer Carrico
By  Jennifer Carrico , Senior Livestock Editor
Cattle producers can determine how to handle the risk of heat stress by referring to the Beef Cattle Temperature Humidity Chart. (Chart courtesy of Rob Eirich, UNL Extension)

REDFIELD, Iowa (DTN) -- As summer temperatures start to climb, along with humidity and stagnant air, cattle producers should be aware of how the heat can stress their animals. Preparation can help prevent poor weight gain, sickness, or even death.

"Typically pasture cattle aren't as susceptible to heat stress as feedlot cattle," said Grant Dewell, Iowa State University Extension beef veterinarian. "Pastured cattle have the ability to seek shade, water and air movement to cool themselves. Radiant heat from dirt or concrete surface is increased for feedlot cattle. At temperatures above 80 degrees Fahrenheit, cattle endure physiological stress trying to deal with their heat load."

Dewell said cattle cannot dissipate their heat load very effectively as compared to other animals, since they don't sweat effectively and rely on respiration to cool themselves. The fermentation process in their rumen generates additional heat in their body.

"During extreme weather conditions with insufficient environmental cooling at night, cattle will accumulate heat that they cannot disperse," he said.

DTN's Livestock Market Analyst ShayLe Stewart said one of the biggest concerns for feedlots usually during the dogdays of summer is remaining current in marketings as showlists normally become more burdensome during these months. This keeps the heaviest feedlot cattle moving through the system and prevents loss of these animals.

"Thankfully, showlists are extremely current this year as packers have had to actively procure more cattle from the cash market to ensure they have enough product to market to retailers," she added. "But with hotter temperatures spanning across the U.S. this week, feedlots are keenly aware that cattle gain less (weight) and convert feed poorly when they're stressed by the heat."

RECOMMENDATIONS FOR FEEDLOT CATTLE

Rob Eirich, University of Nebraska-Lincoln (UNL) Extension educator and director of Beef Quality Assurance located at the Panhandle Research and Extension Center in Scottsbluff, Nebraska, said airflow in feedlot pens is very important to help animals cool down, as well as providing shade and sprinklers to help limit heat stress on those cattle. Ample access to water is important as well, as water consumption is the fastest way to reduce body temperature.

UNL developed a chart to help producers determine the risk facing cattle based on the temperature and the percent of relative humidity, Eirich said. The chart is based on research done by UNL and the USDA Meat Animal Research Center in Clay Center, Nebraska. The chart can be found at http://goo.gl/….

Eirich recommended on hot days feedlots process cattle early in the morning hours before 10 a.m. Working cattle can increase body temperature depending on the environmental conditions and processing time.

Some say handling cattle in the evening is good, but there is still a risk due to the animal's body temperature being elevated from high outside temperatures, Eirich said. He recommended that during the hottest season cattle be worked in smaller groups, so they don't stand in holding areas much longer than 30 minutes. Cattle producers should also consider having shade and good air movement in facilities.

"Work cattle slowly and use low-stress handling techniques," he said. "Processing cattle in any temperature elevates the animal's core temperature."

Eirich also suggested feedlot operators should consider reading UNL's NebGuide titled "Feedlot Heat Stress Management Guide" which can be found at http://goo.gl/….

WEATHER COMBINATIONS CAN CAUSE PROBLEMS

DTN Ag Meteorologist John Baranick said it is most important to watch the combination of temperature and humidity, and especially with fat cattle as they seem to be more susceptible to those conditions. "Truly, the combination of heat and humidity is bad for all animals, but to what degree is that dangerous for cattle is what needs watched," he said.

Still air with hot humid conditions and no clouds or precipitation becomes blistering. Lower temperatures at night help relieve the animals and forecasts into the 60s at night with winds acts as a nice air conditioner for them, Baranick said. Highs in the mid- to upper-90s with dewpoints in the upper 60s to mid-70s aren't good for any animals.

OTHER FACTORS TO WATCH

Dewell said to especially watch the heavier cattle in a feedlot when conditions are hot and humid as they cannot handle heat stress compared to lighter weight cattle. The increase in fat deposition prevents cattle from regulating their heat effectively. Black-hided cattle can have more problems with heat than other hide colors.

"Cattle that had severe respiratory disease early in the feeding period will have decreased ability to regulate their heat load," he added. Extra water tanks can be added to pens to be sure cattle are consuming the proper amount of clean water. He recommended a 1,000-pound animal needs about 1.5 gallons of water per hour.

Another recommendation is to feed cattle at least 70% of their feed two to four hours after peak ambient temperatures as heat production from feed intake peaks four to six hours after feeding. Changing the ration by lowering the energy content of the diet can decrease the heat load also.

Fly control is also important for both feedlot and pasture situations. Biting flies cause cattle to bunch up and decreases body cooling. (For more on how to control different flies to provide economic losses, see https://www.dtnpf.com/….)

Stewart said if feedlots remain current it gives feedlot owners more leverage in the marketplace when packers cut throughput as soon as boxed beef prices top seasonally. "Continuing to monitor boxed beef demand and prices, along with slaughter speeds, remains a top priority in keeping up to date on the live cattle/fed cattle market," she added.

Staying current on marketings and implementing additional strategies during summer heat, while monitoring cattle prior to and during a stress event, will help minimize the impact because of heat stress.

Editor's note: This story includes information from previously published DTN stories by DTN staff.

Jennifer Carrico can be reached at jennifer.carrico@dtn.com

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Jennifer Carrico