Planned prevention is necessary to abate heat stress.
It was a long, hard winter, and most cattlemen have eagerly awaited warmer temperatures. However, when the thermometer’s mercury climbs too far in the other direction, it can still cause issues.
Heat stress is easy to recognize in cattle, says Lindsey Hulbert, assistant professor in animal science at Kansas State University (K-State), when cattle start breathing heavily and panting. Noticing acute heat stress is much easier than preventing it.
Robbi Pritchard, distinguished professor in animal science at South Dakota State University (SDSU), says cattlemen need to pay attention and work ahead. By the time cattle are visibly showing signs of advanced heat stress, it is too late to do much good.
Cattle suffering from heat stress don’t perform well. Feed intake declines and, Terry Mader of Mader Consulting LLC notes, black-hided cattle are more susceptible to heat stress than light-colored cattle.
“The biggest thing to realize is that heat stress isn’t a one-day event. You have to do the preparation ahead of time. Cattlemen need to have a plan in place in May so they can intervene before cattle start dying,” he emphasizes.
Here are 10 factors to consider for your heat-stress-abatement plan.
1. Shade
Shade has been getting more attention from researchers. For creating shade, Mader suggests using shade cloths about 100- to 200-feet (ft.) long and in 12- to 20-ft.-wide spans. Shade structures should be a minimum of 10- to 12-ft. high to allow a breeze underneath.
He says he tends to prefer a north-south orientation so shade moves throughout the day. This makes cattle move throughout the day and decreases the amount of mud and water buildup beneath the structure. However, this method does result in the ground the shade moves to having to be cooled. He says on really hot days, the floor of a feedlot pen can easily reach temperatures as high as 140° F.
2. Sprinkling
Sprinkling can cool down animals and pens alike. Mader says a cooler pen floor helps cattle dissipate heat more easily.
Sprinkling is most effective at night. Pritchard says at the SDSU feedlot, they run sprinklers at 6 p.m. and again at midnight, wetting about 30 square feet of mound space per steer. The water draws heat away from the surface of the mound.
He recommends two to three sprinklings to avoid creating mud. In the morning, steers are often observed standing where the ground was sprinkled, and those areas of the pen are often 20° F cooler.
3. Soaking
In severe cases of heat stress, an option is to thoroughly soak cattle with cold water. This can shock the system if done too late. If done preemptively, soaking allows the heat in the body to transfer away from the cattle.
Fully soaking the animal works well in areas with wind because it doesn’t exacerbate humidity. This approach works best if used late afternoon or early evening the day before things become acute.
4. Water quality
“Cattle do sweat and with increased respiration, they lose a lot of water. The heavy breathing cools them down, but they lose water in the process. Cattle need ample access to clean water to make that up,” says Hulbert.
If cattle drink more, it is highly correlated that they will eat more, too. It is important to note that water consumption increases by 20% when the water is clean, so make sure your waterers are cleaned more often in hot weather, Hulbert adds.
5. Diet
Cattle produce heat themselves when digesting feed. Pritchard notes that distillers’ grains usually have a higher fat content, which provides calories without causing as much heat from metabolizing fiber. Be aware of changes in products. Many ethanol plants are beginning to remove some of the corn oil making this less helpful during heat stress.
6. Timing of management
All three scientists suggest shifting more management to the evenings. Mader notes that rumen fermentation creates the most heat three to five hours after eating, and the hottest part of the day is from 2 p.m. to 3 p.m. If you do feed in the morning, feed earlier (prior to sunrise if possible) so cattle can digest food before the hottest part of the day.
Avoid transporting cattle or working cattle during the day in hot weather, Hulbert emphasizes.
7. Pen cleanliness
Organic matter holds heat, Hulbert says. If manure covers the pen floors, cattle can’t get as much conductive cooling from the pen floor. If the ground is warmer, then cattle stand more during the day and will eat less.
8. Bedding
In addition to cleaning the pen of manure, Pritchard recommends bedding pens with straw. The bright-colored straw reflects light so the floor is cooler. He likens it to the same relief as walking from hot asphalt to grass.
9. Fans
Cattle housing will dictate this option, but, if available, fans can create breeze when there is no wind. In humid areas, no wind makes the heat worse, says Hulbert. She says these are more common in dairies, but can still be applicable in some beef operations.
10. Plan ahead
Pritchard suggests creating a shortcut on your computer to the National Oceanic and Atmospheric Administration (NOAA) heat stress forecast map, www.ars.usda.gov/Main/docs.htm?docid=19887.
“Learn to watch the signals, and you can manage heat stress most of the time,” says Pritchard.
Editor’s Note: For an expanded version of this article, read
the complete story beginning on page 86 of the May 2014
Angus Journal, which is available to subscribers at http://angusjournal.epubxp.com/read/account_titles/174018.