As the dog days of summer begin to unwind into fall, it’s a good time to reflect on how heat stress impacted your feeder cattle and explore steps to prevent future crises and improve profits.
Heat stress like what occurred this year is not that unusual and has happened several times over the past 10 years.
The paradox of the feedyard industry revolving around the Corn Belt is two-fold, explains University of Nebraska-Lincoln professor emeritus Terry Mader. The environmental livestock guru has trotted around the globe in his research and consulting work, digging primarily into heat- and cold-stress research.
“Throughout the High Plains and Midwest, crops are grown for livestock feed because they thrive in the wet and humid conditions it takes to produce an inexpensive feed source — the main reason why we have large livestock operations in these areas,” Mader says. “And generally the higher humidity you have, the more problems that presents for livestock that are managed under hot conditions.”
Other factors come into play, as well, such as hide color, genetics, health of the cattle and how far along they are in the finishing pen.
“We’re raising animals that are genetically bred to perform, and to perform, they need to eat,” he explains. “This requires the animal to work harder to balance between climatic heat load and metabolic heat load, especially in the summer.”
When a healthy animal overheats, the first thing it loses is appetite. If plenty of water is available that is reasonably cool, the animal can maintain a comfortable thermo-balance. But if the water supply is compromised and the animal becomes dehydrated, it is unable to expel heat through sweating and panting. As the body temperature starts to rise, breathing is increased to bring in more air for dissipating heat, which eventually can result in a compromised respiratory system.
“Even if the animal is able to make it through the adverse heat event and get cooled off, its physiological components may not function properly and the animal could still die,” Mader explains. “There are also findings that cattle which have been severely heat stressed are more likely to develop intestinal-track problems, which they cannot overcome.”
There are two main strategies to reduce heat stress on feedlot cattle, Mader says, and they both require some thought and some investment in infrastructure.
“One of the most effective ways to cool cattle down is by spraying them with water,” Mader says. “The evaporating water operates like sweat. However, there are some implications producers need to keep in mind.”
According to him, cattle sprayed with water during hot days will quickly adapt to it. If those cattle are not consistently wet down after their bodies adjust, they can become metabolically compromised and at greater risk for heat stress.
Another factor is mud development and humidity levels.
“Cattle are going to lie down in the pen, and if there is mud on their hides, it is going to make it even harder to manage heat,” he explains. “It’s also important to keep the pen from getting too wet so humidity levels don’t increase even more.”
Sprinkling systems are also going to increase the use of water resources and employee labor if a watering truck is used. In research done by Mader, he found that feedlot water use could increase two to three times when sprinkling systems were utilized.
An increasingly popular preventive method of heat stress is installing shading systems into feedyard pens. In research published in the 2002 Journal of Animal Science by Mitloehner, Galyean and McGlone, shading on a test group of feeder heifers increased dry-matter intake to 21.56 pounds per day, compared to 20.94 pounds per day by non-shaded counterparts. Average daily gain also increased from 3.61 pounds per day to 3.82 pounds per day. The biggest results were seen in quality, with 55.8 percent grading Choice, compared to the non-shaded test group grading 36.2 percent Choice. The researchers also noted that the shaded pen of cattle had 50 percent less dark cutters than the non-shaded group.
When looking to implement shading systems, there are many factors to consider, Mader says. First off is the choice of materials: metal or cloth.
“Unless it is built really well, tin can come loose and flap through feedyards; however because metal shading is more permanent, it can handle snow load in the winter,” he says. “Right now, we’re seeing a lot of shade cloth put up in the spring and taken down in the fall prior to winter. While it doesn’t have the lifespan of a metal structure, it is priced reasonably and doesn’t have to have as [much] structural integrity.”
Feedyard producers also need to be diligent in the placement of the shading structures, calculating shade movement with the sun and finding what positions will give cattle optimum coverage throughout the day, particularly when temperatures reach their highest points.
“Generally, shade from north and south orientation will move with the sun, but east to west shade won’t,” he says. “Orientation that doesn’t move is the best because the ground remains cooler. However, more urine and fecal build up under the shade will require more maintenance.”
Perhaps even more important is height and spacing of shading systems. Mader suggests producers allow 20 to 25 square feet per animal for shading and says the shades should be at least 12 to 20 feet off the ground so airflow isn’t restricted.
“Bottom line — if we are going to produce high-performing cattle, it is our responsibility to make sure they can handle environmental stress, whether it be hot or cold,” Mader concludes. “Weather is something that is unavoidable and there is not one thing that can be done to make environmental stress go away, so it is best to be equipped for it the best we can, using multiple strategies.”