By David Hartman
In the hottest part of summer, cattle managers need to consider heat stress in their stock and how it can be mitigated. It is better to plan and strategize ahead of time rather than react after the heat wave begins.
Whether in a pasture or in a feedlot, cattle can suffer heat stress. Environmental conditions that contribute to heat stress include minimal cloud cover, little to no air movement, high relative humidity, and high overnight low temperatures (above 70°F).
Researchers at the Meat Animal Research Center (MARC) have identified four primary areas that influence an animal's response to heat stress. Those four factors are genetics, health, production status, and previous exposure to heat.
Lighter colored cattle generally show less heat stress than darker colored breeds. Research has shown that in a group of genetically closely related cattle with different hide colors, cattle with dark hides had a 2°F higher core body temperature. And, calmer cattle have been shown to be more heat-tolerant than excitable ones.
MARC research has shown that feedlot cattle treated for pneumonia at any time between birth and slaughter have a 10.5% higher respiration rate under stressful conditions than their untreated peers another good reason for implementing preconditioning programs for calves.
Heavy feedlot cattle are at more risk. Additionally, very young and very old animals are at more risk.
What cattle are eating plays a role in heat stress. Excessive protein levels can be problematic. This could occur in pastures and in feedlots. The excess nitrogen in the protein must be biochemically removed and excreted through urine, using energy and generating heat in the process. Additionally, there are differences between cattle fed grain and those fed only hay. Feeds such as corn contribute less to the heat of fermentation than hay. High-quality forages produce less heat of fermentation than low-quality forages.
With all this said, what can we do? Some of these things we can control, and some we can't.
Source : psu.edu