All eyes now are on the rapidly approaching summer season and how the temperatures could impact feed conversion for livestock producers and feedlot managers. At this point, the latest Climate Prediction Center’s summer outlook (maps below) indicates that we may see a cooler than average summer. While cooler weather does suggest animals would be more comfortable, interestingly a beef specialist from the University of Nebraska advises, that’s not always the case when there’s a lot of moisture or high precipitation levels. Sometimes when humidity is elevated enough, ranchers don’t necessarily reap a huge benefit from the cooler temperatures.
“A case in point: more often than not – our wetter years will potentially create more heat stress, than our very dry years. It’s cooler, but the cattle don’t get a chance to adapt to higher temperatures. So, when we get a sudden change in temperature in late July or August – cattle can still be carrying a partial winter hair coat because they haven’t had a chance, at that point to adapt to hotter conditions,” said Terry Mader, Ph.D., president of Mader Consulting LLC., and Professor Emeritus; Livestock Specialist in Environmental Stress at UNL.
If it stays cool, it’s a win/win for everybody. “In that case, when temperatures are about three to four degrees below normal, then we could see a two to three percent improvement in feed efficiency,” noted Mader, retired from UNL, and actively consulted about his environmental stress work with cattle.
“Yes, I can see cooler conditions possibly translating into better feed conversions. However, if the pens are still in poor condition from the previous winter’s feeding period and are muddy, I can see mud offsetting any gains,” said Dale Blasi, Ph.D, Beef Extension Specialist-Ruminant Nutrition at Kansas State University, also manager and director of the KSU Beef Stocker Unit and Animal Identification Knowledge Laboratory, a facility designed to evaluate existing and emerging animal identification technologies.
“However, if we end up with a two to three-week period of high temperatures and humidity, it would negate all, or most of the benefit of the cooler temperatures we’ve had prior to that, in that case,” Mader advised.
Mid-July to mid-August would be the period we could potentially have the most disastrous effects when temperatures are high enough and humidity levels stay elevated. “If temperatures spike by five to eight degrees above what we’ve been seeing…then you have about two days that the animals can handle that. After that,” Mader says, “We’d start seeing animals being compromised. If conditions persist for one to two weeks, then feed intakes become compromised by as much as 30 to 50-percent until the cattle get adapted to those conditions,” he added.
The way that that most cattle manage heat stress, is they’ve got to cut down on the metabolic load. So, Mader says there are two things to consider: “There’s metabolic heat load from metabolizing feed, and climatic heat load. If the climatic heat load is high enough, the only way the animal can mange heat is to reduce feed intake,” said Mader.
This is particularly linked, not just when daytime temperatures get high, but when nighttime temperatures are high for an extended period of time (see map and chart below for examples). “This condition means that the animals don’t have relief from the heat stress during the overnight hours (as they would usually during the summertime when the temperatures drop to, for example, 75-80 degrees F). Several days of heat stress with no nighttime respite can certainly lead to mortality,” explained Katrina Frank, Bioclimate Consultant with Applied Climatologists, Inc. Mader also suggests…in summer, staying current on your cattle marketing. “I advise not holding cattle for a better market particularly during July and August. If they’re finished, get them to the packing plant instead of holding cattle and trying to recoup losses you may have had in late winter and spring,” said Mader. The reason? Holding cattle for a better market in September may not be cost effective, if cattle get heat stressed in July and August.
For the last couple of decades the trend has been for hotter summers so it will be interesting to see if we finally get a cooler summer. We’re just getting into June and we will continue to track conditions as they evolve over the next three months.