News Update: Heat Stress
August 9, 2010

Protect Your Cattle and Yourself From Heat Stress

Be careful, it’s hot out there. U.S. Department of Agriculture (USDA) Agricultural Research Service (ARS) maps show a large portion of Central and Southern parts of the U.S. to be in emergency heat watch zones. To view the maps, click http://www.ars.usda.gov/Main/docs.htm?docid=19890. To view USDA-ARS pictures of the different stages of heat stress in livestock, click http://www.ars.usda.gov/Main/docs.htm?docid=15625. For advise on how to take care of your cattle in heat stress, click http://www.ars.usda.gov/Main/docs.htm?docid=15627, and also read the articles below from Angus Productions Inc. (API) coverage of the International Symposium on Beef Cattle Welfare (ISBCW) and university publications on heat stress.

Drink plenty of water, don’t push yourself too hard, and try to stay cool.

Soaring Temperatures, Humidity Take Toll on Cattle

Compared to people, cattle have a distinct disadvantage when it comes to handling some kinds of heat. Soaring temperatures and high humidity are taking a deadly toll, a Kansas State University (K-State) veterinarian said.

“Cattle lack the ability to sweat significantly, so it is critical that producers and livestock handlers take steps to reduce heat stress before conditions become dangerous,” said K-State Research and Extension Veterinarian Larry Hollis. “High daytime temperature by itself rarely causes problems. It is a combination of the humidity with heat that creates the maximum heat load on cattle.”

He cited this month’s reports in Kansas of hundreds of cattle deaths attributed to the weather mix. Temperatures well into the 90º F range coupled with high humidity levels to push heat indices to 105º degrees or above.

Other factors compounded the cattle’s lack of ability to perspire. Several days in a row of high temperatures, a lack of nighttime cooling, lack of shade or cloud cover, lack of wind, lack of air movement in pens, and grazing on endophyte-infested fescue pastures can all create problems for cattle, Hollis said.

In addition, animals with dark hides and/or heavy body weights, as well as those in advanced stages of pregnancy are particularly vulnerable to the consequences of such weather.

“Producers should watch for signs of heat-related distress during hot, humid weather. The signs can include cattle going off feed, standing with their head over the water source, panting, salivating excessively, or open-mouthed breathing,” he added.

Producers and feedlot managers should consider ways to alleviate the stress, when possible, including:

• Avoid gathering or working cattle after mid-morning;
  
• Provide access to abundant cold water/waterer space and make sure the water flow rate is adequate;
  
• Provide access to shade;
  
• Provide the ability to move away from anything that reduces airflow, even cutting down weeds around pens;
  
• Use sprinklers — wet the skin;
  
• Control flies;
  
• Make arrangements with fire department.
  

“And, don’t forget about the people,” Hollis added.

— Release by K-State Research and Extension.

Keep Cattle Alive By Combating Heat Stress

“Cattle don’t get hot and die; they get hot and then die the next day,” said Dee Griffin, professor at the University of Nebraska Veterinary and Biomedical Science Department. Speaking at the ISBCW, Griffin explained several factors involved with heat stress in cattle.

Heat stress occurs when the heat load is greater than what the animal can dissipate, Griffin noted. There are three different types of susceptibility factors to heat stress:

• Inherent factors, including hair color and genetics;
  
• transient factors, including age, acclimation, nutrition and health; and
  
• environmental factors, including temperature, humidity, wind speed and overnight low temperatures.

Low temperatures reached overnight are key to timing cattle processing, Griffin said. When trying to work cattle in the late evening, he realized the cattle were not getting cool enough and they were still having problems with heat stress and death. Working cattle of an evening may be cooler for those working, but the core body temperatures of the cattle are just peaking, he explained, adding that he now waits till 4 a.m. to begin processing on extremely hot days.
Griffin also advised feeding during evening hours so the heat caused by digestion will occur during the cooler evening hours.

The design of an operation can play a role in how much the heat will stress an animal. Griffin advised putting tall mounds around the lot, explaining they can increase wind speeds by 3-5 miles per hour for cattle standing on top of them. Griffin encouraged getting rid of all windbreaks (unless winter weather is extreme) as they can block airflow during summer months.

Along with the welfare issues, heat stress can cause economic losses. A decrease in feed intake and increased susceptibility to diseases are two examples Griffin gave.

Recognize the high-risk groups and signs of heat stress early, Griffin advised. “Do what it takes to keep them comfortable.” Ask the local fire department to come out and spray the cattle with water to help them cool, he offered as an example. Steroids and IV fluids can also be used in extreme situations to save a life.

For more information on improving cattle welfare from the ISBCW, visit http://www.api-virtuallibrary.com/meetings_other_news.html.

— by Mathew Elliott, assistant editor, Angus Productions Inc.

Tool Available to Help Livestock Producers Determine Extent of Threat From Heat, Humidity

A string of hot, humid days through much of the Plains and Midwest this summer have taken a toll on cattle, according to K-State Veterinarian Larry Hollis.

To help cattle producers and feedlot managers determine the risk of such conditions, the University of Nebraska developed a Temperature-Humidity Index. The index is part of a Livestock Weather Hazard Guide, posted on the Ardmore, Okla., website of the Samuel Roberts Noble Foundation: www.noble.org/Ag/Livestock/Heat/.

“When there is no daytime wind and/or nighttime temperatures do not drop below 75º degrees so conditions reach a score of 75 (on the Temperature-Humidity Index), producers should be on the alert for heat stress problems,” Hollis said. “When the index reaches 79, the situation has reached the danger point. An index of 84 means emergency conditions exist.”

Panting scores probably give the best visual method to estimate the severity of heat stress on cattle, he added. If cattle are panting at a rate of 80 to 120 breaths per minute, they are in moderate stress; 120 to160 breaths per minute mark the danger zone; and more than 160 should be considered an emergency.

“When they see signs of moderate heat stress, producers may have a very short time to provide a mechanism for cooling the cattle before the situation becomes life-threatening,” the veterinarian said.

— Release by K-State Research and Extension.

Cool Off and Watch ‘The Vita Ferm Angus Hour’

The popular live television show returns to RFD-TV, with a focus on preweaning and weaning management.

Weaning your calves can be a difficult strategy to master. Their health and performance — and your wallet — are on the line. Tune in to “The Vita Ferm Angus Hour,” 7 p.m. (CST), Monday, Aug. 9, on RFD-TV to hear industry experts discuss complete preweaning and weaning strategies to help unlock your profit potential.

The hour-long program also will feature live audience questions for the panel, which includes Howard Jensen, nutritionist for Biozyme Inc.; and Larry Corah and Mark McCully, Certified Angus Beef LLC (CAB). Read more.

— Compiled by Mathew Elliott, assistant editor, Angus Productions Inc.