Triple-digit temperatures stressing beef cattle and calves

Writer: Robert Burns, 903-834-6191, rd-burns@tamu.edu

COLLEGE STATION – As temperatures reached 100 degrees and above, the stress on beef cattle increased, said Texas A&M AgriLife Extension Service experts.

Though there are no reports of large death losses yet, the stress does affect beef cattle health and certainly reduces their feed efficiency and daily gains, both on pastures and in the feedlots, the experts said.

“The really high temperatures we’ve had the last several weeks have caused cattle to undergo a lot of heat stress,” said Dr. Joe Paschal, AgriLife Extension livestock specialist, Corpus Christi. “Typically, cattle are going to shade up a lot more, particularly if they are black-hided rather than if they are of Bos indicus or Brahman influence.”

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Paschal said in addition to staying in the shade much of the day rather than grazing, cattle are going to look for ways to cool off, such as standing in ponds or stock-water tanks.

If these measures aren’t enough, then they will start showing physiological signs of heat stress, he said. Cattle mainly cool themselves by panting. Bringing in cool, moist air will allow them to lower their core temperature, and by turn, their outer body by increasing the amount of blood to their hides.

“If they can bring cool air into their lungs, that’s fine, but they can’t now,” Paschal said. “They are bringing in air that’s at 100 degrees and at very low humidity, and it’s making them even hotter. This affects their entire metabolic process. It’s even harder on feedlot cattle as they’re fatter.”

Dr. Ted McCollum, AgriLife Extension beef cattle specialist, Amarillo, said it is true that feedlot cattle are more susceptible to heat stress. This is because they are generally fatter or “fleshier,” and the fat acts as an insulator, making it harder for them to dispel heat by convection.

However, he hasn’t heard that many reports on death loss this summer, he said.

Of the 120 or so feedlots that finish cattle in Texas, Oklahoma and eastern New Mexico, most are in the Texas Panhandle, McCollum said. And one of the several reasons that most confined cattle feeding units are there is because of the climate.

“The one thing about this part of Texas as compared to South Texas, or farther north in Nebraska where you hear about death losses from heat stress in feed yard cattle, is that we do cool down at night,” McCollum said.

The cooler nighttime air means cattle in Panhandle feed yards have the chance to “unload” that heat at night.

This isn’t to say that some cattle in Panhandle feed yards haven’t suffered health problems during the past several weeks, but to his knowledge there haven’t been any large-scale problems, he said.

Some performance losses have occurred because of reduced feed consumption during the hot weather. Digestive processes generate body heat. So in response to hot ambient temperatures, cattle will often reduce feed intake in an effort to reduce their heat load, he said.

AgriLife Extension district reporters compiled the following summaries:

Coastal Bend: Some parts of the region had not received rain for nearly four weeks. Others got a few scattered showers, but nothing significant. The dry conditions helped farmers get some crops harvested, but some had to irrigate soybeans and cotton. The dry weather was expected to reduce the yield potentials of soybeans and hay fields. Many producers were taking a second cutting of hay, but grass regrowth was slow to non-existent due to lack of topsoil moisture. The corn and grain harvests should be completed by the middle of August. Rice was starting to arrive at grain elevators. Livestock owners were checking water sources daily to assure all livestock had adequate water. Cattle were generally in good condition, but more calves were being shipped as forage supplies began to wane.

East: Most counties reported temperatures above 100 degrees, along with dry and windy conditions. All counties needed rain. Pasture and hay fields were showing drought stress. There was a general browning of all grasses, and a great reduction in regrowth. Producers who had overstocked their pastures were beginning to run out of grass. Soil moisture continued to dwindle. Most counties rated topsoil as short, with several rating it as very short. Burn bans were being issued throughout the region. Many Anderson County oak trees were dying. Vegetable harvesting was nearly over. Some truck farmers were preparing for fall planting. Pond and creek levels were dropping. Cattle were in good condition. Weaning and selling of market-ready calves and cull cows continued. Some producers were supplementing livestock with protein. Horn flies continued to be a problem. Feral hogs were on the move, rooting up pastures and lawns.

Far West: The entire region had temperatures well above 100 degrees. A few counties received measurable rainfall. Dryland cotton in Glasscock County was showing signs of heat and moisture stress. Cotton in most other counties was in good condition, at full bloom and setting bolls. Corn was in fair to good condition. Alfalfa growers were taking a fourth cutting. Pecans looked good. Sorghum crops were in fair condition. Pastures and rangeland were beginning to dry out but were in fair to good condition. Subsoil and topsoil moisture ranged from adequate to short. Cattle were generally in good condition. Calves and stocker cattle were gaining weight.

North: Temperatures reached 100 degrees every day. Topsoil moisture was short to very short. The ground was cracking in many places, and pastures were drying out very quickly. Producers continued to harvest Bermuda grass hay and annual forage sorghum. Corn and grain sorghum were maturing very quickly, with harvesting likely to begin in the next week or two. Yields of both crops were expected to be below average as both were planted late due to excessive rain during the spring and early summer. Soybeans were struggling with the heat. Sunflowers looked good in some areas but were stressed in others. Livestock were in good condition for August but were seeking refuge in stock tanks and waterways to stay cool. Flies and mosquitoes were abundant. Wild hogs continued to cause damage.

Panhandle: The region remained hot and humid, with temperatures near normal for early August. Isolated areas received showers, from a trace to 3 inches. Grasshoppers were a problem throughout the region. Spider mites were being monitored in Deaf Smith County corn fields, along with sugarcane aphids in Hansford and Lipscomb counties. In Collingsworth County, the hot weather added much needed heat units for cotton and sped up the maturing of grain sorghum. Irrigators were watering cotton while the crop was setting bolls. Deaf Smith County producers were evaluating damage from the past storms. Several corn, sorghum and wheat fields were totally lost. Otherwise, Deaf Smith County crops were generally in good shape, with much of the corn in the milk to early dough stage. Grain sorghum was coming along well too, with early planted fields setting seed. Cotton was struggling as many fields were behind and needed more heat units. Gra sshoppers were particularly bad in Deaf Smith County, with many producers having already sprayed multiple times in an effort to control the invasion. Producers were concerned about planting early wheat until the grasshopper problem was resolved. In Hall County, extremely hot weather stressed crops and livestock. Hansford County received another 1.7 to 2 inches of rain. Weeds were becoming a big problem in some fields. Corn looked great, and some irrigation pumps were turned off to allow cutting of silage. Irrigated and dryland sorghum looked great. Irrigated cotton also looked very good. Dryland cotton stands were spotty in places. Lipscomb County reported sugarcane aphid infestations in grain sorghum. Randall County crops continued to progress after some rain. Wheeler County cotton was still behind normal development.

Rolling Plains: Summer heat hit the region, with high temperatures ranging from 100 to 107 degrees. The heat rapidly dried out topsoils but was good for most cotton, though some fields were showing signs of stress. Summer annual forages were being harvested. There were reports of sugarcane aphids on grain sorghum. Cattle were in good condition, and pastures were holding up, though some grasses were drying out quickly. Grasshoppers were still damaging trees and crops, but populations were declining.

South: Very hot and dry conditions were the rule throughout the district, and soil moisture levels were dropping. In some areas, there had been no rain for as long as six weeks. In the northern part of the district, corn and sorghum harvesting continued. Peanut development ranged from the flowering stage to setting pods. Cotton was opening bolls. Pastures and rangeland were drying out, but they generally were still in fair shape. Some producers were baling hay. Body condition scores of cattle remained good. In the eastern part of the district, most pastures still looked good despite the lack of rain, but producers expected they will have to provide supplemental feed to livestock soon if there is no rain. The grain sorghum harvest was underway with some producers reporting yields of 5,000 pounds to 6,000 pounds per acre. Small fires broke out in rangeland and pastures in Jim Hogg County. Cotton growers did not expect harves ting to begin in earnest until Sept. 1. Soil moisture in the eastern counties ranged from adequate to short. In the western part of the district, the continuing hot, dry weather meant producers still had to irrigate cotton, pecans and some late-planted sorghum fields. The harvesting of corn and sorghum was active. The availability and quality of native rangeland and pastures grasses further declined. Producers who had heavy grazing pressure on native rangeland had to provide light supplemental feeding. Cotton was making good progress. In the south part of the district, soil moisture was short. Producers were defoliating cotton, and the sugarcane harvest was ramping up.

South Plains: Temperatures were in the triple digits, which for some counties was a first for the year. Cotton development ranged from just beginning to bloom, with eight nodes above white flower, to physiological cutout with five or fewer nodes above white flower. The heat was generally good for cotton in helping it somewhat catch up on development. Floyd County cotton started to set bolls, and grain crops continued to look great. Hale County received timely, scattered showers that provided significant moisture in a few areas. Cochran County also received showers that improved subsoil and topsoil moisture. Peanuts there were doing very well. Sugarcane aphids were confirmed in grain sorghum, while cotton was impacted by fleahoppers and lygus bugs during the last few weeks. Lubbock County recorded its first official 100-degree day on Aug. 6. However, temperatures had been consistently near 100 for days, with higher than normal humidity. Spotty rain showers amounted to 0.5 to 1 inch of moisture. Cotton was stressed where no rain was received. Grain sorghum producers were closely monitoring widespread sugarcane aphid infestations. Some fields reached economic threshold levels for treatment. Garza County also received rain, from a trace to as much as 2 inches. Cotton continued to progress but needed rain to maintain development. Mitchell County had several 100-degree days. Rangeland condition declined, and the increased chances of wildfire became a concern.

Southeast: Soil moisture varied widely throughout the region, but was mostly in the adequate to short range, with short being the most common. Rangeland and pastures were mostly rated in fair to poor condition, with fair ratings being the most common. Temperatures were at or above 100 degrees. Soils and lowland areas were drying out. Pasture conditions were beginning to fade. In some areas, there had been no regrowth of grass after the first cutting of hay about three weeks ago. Corn was drying down very quickly. In Chambers County, early rice that did not have to be replanted was being harvested. Dry conditions made draining rice fields a hard decision, but the alternative was to chance plants dying and lodging. In Fort Bend County, the grain sorghum harvest was mostly finished. Yields ranged from 3,500 pounds to as much as 7,500 pounds per acre. The corn harvest began, with yields ranging from less than 100 bushels to as muc h as 240 bushels per acre. Cotton was progressing quickly, and some producers expected to begin defoliating within a week. Livestock were in fair to good condition.

Southwest: Hot, dry conditions persisted throughout the region with no rain reported. Temperatures have been in the high 90s to over 100 for weeks, which was cooking grasses and forbs. Burn bans were instituted in some counties. The grain sorghum harvest neared completion, and the corn harvest was in full swing. Pasture conditions continue to decline with hot and dry conditions. Hay yields have been very high, but most fields were already going to seed or becoming dormant. Cotton was doing well. Wildlife generally were in good condition. With pastures declining, due to the hot weather, livestock were showing signs of stress.

West Central: The region had triple-digit temperatures with no rain forecast. The continued hot, dry, windy conditions were drying out soils, pastures and stock-water tanks. Row crops were showing signs of heat and moisture stress. Some producers were preparing fields for fall planting, but many were waiting for a rain before beginning. The danger of wildfire was high and increasing every day. Cotton was maturing fast thanks to the hot days and warm nights. The grain sorghum harvest began. Hay harvesting continued, with many producers taking a second cutting. Some expected to get a third cutting. Grasshoppers were becoming an issue in some areas, and producers were applying pesticides. Rangeland and pastures remained in fair to good condition, but were beginning to show signs of stress. Livestock remained in fair to good condition. Calf weaning continued.

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