When temperatures rise, cattle appetites tend to drop. Producers need to consider adjusting the ration or changing environmental factors to help manage cattle during times of extreme temperatures. This is especially important when developing heifers for replacements or raising yearling bulls in a dry lot setting.
Dr. Brad White, Dr. Phillip Lancaster and Dr. Bob Larson discuss heat feeding on the KSU Beef Cattle Institute’s Cattle Chat podcast, which aired July 26.
“Feed intake is going to drop off so that means energy intake is going to decrease,” Lancaster says. “You’re not going to get the performance you want from just two aspects, one being that maintenance requirements are going to go up because they’re trying to get rid of that extra heat and then two, they’re not getting as many calories.”
Lancaster offers a couple options for producers when adjusting rations.
“One of the things that we can try to do to alleviate is to increase the energy density of the diet,” he says. “We can decrease the amount of roughage in their diet and add more concentrates so that they’re consuming more calories. The other thing that happens is that the heat of fermentation is actually less when they’re fermenting starches in grains when compared to when they’re fermenting forages.”
While it may seem counterintuitive that a higher intensity diet would produce less heat of fermentation, Lancaster explains it’s because those different carbohydrates are fermented to volatile fatty acids.
“When starches are fermented, we don’t have as much carbon dioxide produced during that fermentation as we do with forages and that is the metabolism part of that which creates the heat and so we have less heat per unit of carbohydrate consumed with a starch than with a forage,” he says.
White points out that in a dry lot setting, the meal is provided in a bolus form vs. having cattle continuously grazing on pasture.
“We don’t see as much of a change and they’re in a different environment so it’s hard to compare grazing to this dry lot scenario that we have,” he adds.
Another factor to consider when managing a heat diet is time of day of feeding.
“The peak heat of the day is mid afternoon,” says Larson. “You’ve got the heat of fermentation so we’re trying to avoid having a big belly full right during the middle of the afternoon because that’s going to compound those two things. A lot of people talk about feeding really early in the morning or technically you could do it late evening, so that by the time you’re in the middle of the afternoon they’re starting to get hungry and not as actively creating the heat of digestion.”
Lancaster adds that the heat of digestion and fermentation may last for several hours, but it will peak somewhere around three to six hours after a meal.
“There’s some good research that shows that if you can feed those cattle in the evening in the hot weather then that heat of fermentation is going to happen in the cooler morning hours when they can dissipate that extra heat a lot better and so their performance actually improves quite a bit,” Lancaster says.
In addition, producers could consider not only the type of ration, but the amount of feed the cattle receive during extreme heat waves or temperature shifts.
Lancaster suggests moving toward a type of limit feeding where the diet more energy dense, but also a smaller amount.
“Instead of putting them on full feed, we can limit the amount so we’re getting the right calories for them to grow, but the appetite depression from the heat stress is not going to have as big an impact because we have them on a more energy dense diet,” he explains.
Another big nutrient that must be available at all times, especially during times of increased temperatures, is water.
Larson reminds producers to think about pen size and how many animals are in the space provided.
“One of the things I think to consider is to bring in an extra tank so that there aren’t any animals that are thirsty at all,” he says. “They should be able to get access to that water quickly and shouldn’t have to stand in line.”
A big open source tank that lots of animals can drink out of may be needed in addition to a ball fountain-type waterer because it is not designed to flow as fast, Lancaster adds.
Water sources should also be checked frequently to make sure large tanks remain fresh. Producers will also want to avoid tanks with stagnant water or water sources that do not pump as fast to keep up with the demand of cattle during the heat.
Listen to the full podcast here.
