Restructuring Feeding Schedule can help with HEAT STRESS

Minimizing heat stress can also impact beef quality and cattle performance.

Temperatures on the High Plains where a large number of feedyards are located have set records much of the summer. The scorching heat that Texas had to deal with last year has now spread northward, with forecasted highs of 100-plus degrees as far North as Nebraska is not uncommon.

According to the USDA, several heat events over the last 10 years have resulted in direct and indirect financial losses estimated at over $75 million for the cattle industry.These weather events are unavoidable, but management strategies can reduce the impact of heat waves.

Although some feedyards are accustomed to dealing with extreme temperatures, others are now seeing the need to incorporate additional heat stress management techniques in their operation. One of the easiest adjustments that can be made with little cost is changing the feeding time.

Grant Dewell, Iowa State University Extension veterinarian, suggests feeding in the evening. Or if cattle are fed twice daily, feed 70 percent of the ration in the afternoon.This simple adjustment can help with erratic intake during extreme heat, and helps cattle offset their internal heat load to later in the day.

Heat from fermentation in the rumen is the primary source of heat for cattle, he explains. Heat production from feed intake peaks at four to six hours after feeding. When cattle are fed in the morning, peak rumen temperature production occurs during the heat of the day when they can’t dissipate it. Adjusting feeding times allows cattle to deal with fermentation heat when the ambient temperatures are cooler.

Dr. Terry Mader, University of Nebraska, says basically “we are trying to minimize or diminish a high metabolic heat load from occurring at the same time as a high climactic heat load.” He also suggests moving the feeding time may also reduce any sub-clinical acidosis that could contribute to the problems seen in heat stress.

Understanding how cattle handle heat is also important. Dewell explained that cattle’s core temperature peaks two hours after peak environmental temperature, so they are likely to feel the impact of the day’s heat in late afternoon or early evening. Add to that the fact that it takes at least six hours for cattle to dissipate their heat load, and an animal is not getting significant relief from the day’s temperatures until after midnight.

Mader also suggests feedlots consider lowering the energy level in the feed. Although this is somewhat controversial, research indicates that a lower energy contest may reduce the metabolic heat load on cattle.

Heat stress in the feedyard can ultimately affect cattle quality and performance. In times of extreme heat and humidity, cattle are more likely to back away from the bunk and have inconsistent feed intake,which ultimately reduces daily gain.

Mader says that meat quality can also be impacted. “One thing we see under heat stress is an increased number of dark cutters. It could be the entire muscle is dark,or it could be streaks.”

Another strategy Mader suggests to combat heat stress is wetting down the pen surface, citing that the temperature of the pen surface can reach 140-150 degrees in the hot, summer sun.

Feeding times, ration adjustments and wetting pen surfaces are ways feedlots can deal with heat stress immediately. But analyzing the construction of the feedlot, and considering investing in shades and sprinkler systems is important, too. Although the actual construction of shades or sprinkler systems would be unlikely as a spur of the moment decision at many feedyards this time of year, studying the situation, location and direction of pens, windflow, natural shade, etc. during the summer can help springboard plans for future improvements.

With cattle prices over the last 12 months, an economic factor is also involved.“We are in a situation economically where we have pretty expensive animals out there. We need to make sure they are properly cared for not just from a performance standpoint, but also what the consumer wants,” Mader suggests.

“The consumer wants to make sure the animal from which their family’s beef comes from was cared for properly. That means more than just feed and water, like also doing what we can to protect these animals from the heat.”

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