LEXINGTON, Ky. — The recent extreme heat, high humidity and lack of rain have some area farmers, particularly livestock producers and corn growers, taking precautions to protect their respective products.
“We are looking at an extended period of heat stress, beginning July 15,” said Matthew Dixon, a meteorologist for the University of Kentucky College of Agriculture, Food and Environment. “Daily temperatures in the low- to mid-90s will be common through at least the weekend. These conditions will push livestock heat-stress index into the danger to emergency categories during the afternoon and evening hours.”
Marc Guilfoil, co-owner of Evans Mill Cattle Company in Lexington, said the combination of heat, humidity and drought is a major cause for concern for livestock, as well as other animals.
“When you have cattle or any animal, you sign an unwritten agreement that you’re going to take care of their livelihood,” Guilfoil said. “This heat that we have coming – we get it every year but not as bad as it’s supposed to be the next couple or three days – the main thing is making sure they have access to shade, and you want to keep their stress level as low as possible, so whatever the cattle are used to doing, or whatever animal you have is used to doing, keep doing that. And, of course, make sure they have access to clean water.”
UK beef specialist Jeff Lehmkuhler said in addition to cool, clean water and shade, transporting animals during emergency heat stress should be avoided.
Nikki Whitaker of the Kentucky Cattlemen’s Association said annual regional droughts are not uncommon, and cattle are more susceptible to heat stress because they are not able to sweat effectively.
“When cattle are under heat stress, they lose weight and don’t perform as well,” Whitaker said. “For a beef cattle farmer, animal health and weight gain are essential, so keeping cattle cool and comfortable is extremely important. In Kentucky, most of our cattle are grazing in pastures and typically pastured cattle aren’t as susceptible to heat stress because they have the ability to seek shade, water and air movement to cool themselves. Our farmers are equipped with the knowledge of how to proactively manage their herd and land for when extreme heat and dry periods happen.”
University of Kentucky Extension Professor and Director of the UK Grain and Forage Center of Excellence Dr. Chad Lee said corn crops could be adversely affected by extended periods of high heat and humidity as well.
“Corn’s defense against warm weather is that any single plant will drop most pollen during the morning and will drop less pollen later in the afternoon or evening, thus, avoiding the hottest part of the day,” Lee said. “Adequate water and relative humidity will help. Heat can quickly dry out the pollen grains.”
Temperatures above 90 are detrimental to pollen and can dry out corn silks, Lee said.
“If the pollen or silks are dry, pollination will not occur,” he said. “Back in 2012, extremely hot mornings combined with low humidity and dry soils all conspired to damage pollination. Even with the forecasts, 2020 is in a much better situation than 2012, but there are risks to pollination in 2020.”
The decrease in the availability of corn could hurt the three biggest markets for Kentucky corn, which are livestock producers, distilleries and exporting the crop to Mexico, Lee said. With about a third of Kentucky corn crop in the silking stage and the other two-thirds pollinating in the next week or two, the length of a dry heatwave is pivotal.
“Everything hinges on favorable conditions for about a three-week period and, more specifically, on the week that a corn plant pollinates,” Lee said. “Enough water during seed fill is critical as well, but we must get the kernels established before they can be filled. In a normal year, a corn plant at peak water demand usually requires about .3 inches of water per day. If temperatures are in the upper 90s, water demand will be greater. We may get good pollination because of pollen drop in the mornings and because of relative humidity, but the heat will remove some yield potential from the plants.”
Horses have difficulty regulating their body temperature when temperatures exceed 90 degrees, according to a press release from the University of Kentucky Department of Agriculture. If humidity is high, the temperature doesn’t even have to reach 90 degrees to make life uncomfortable for horses. Unlike cattle, horses do sweat, but if the humidity is high, they may not cool as efficiently as normal, according to the release.
“Horse owners can reduce heat stress by scheduling activities during the cooler part of the day and making sure horses have plenty of water,” said Bob Coleman, UK equine extension specialist. “If you do transport horses during the cooler part of the day, give water before, during and after transportation to reduce the risk of dehydration.”
Coleman added that even non-working horses will double their water intake during hot weather. Owners should allow them to drink often to help maintain water balance.
“If you let them drink often, it can relieve the horse’s urge to drink a lot of water after exercise, and they need to gradually drink after a workout,” he said. “Also, remember lactating mares have special water requirements because they are using water for milk production as well as body temperature regulation.”
Hot weather also increases horses’ need for salt, because they lose the mineral during sweating.
Poultry is especially prone to heat stress. Mortality during extreme heat can be significant, and egg production and hatching rates can drop, according to the press release.
“Since the birds don’t have sweat glands to help get rid of excess body heat, they have to pant to cool down,” said Jacquie Jacob, UK poultry project extension manager. “It’s important to make sure chickens are in well-ventilated areas and they have access to clean, cool water at all times.”