Climatology: The effects of heat stress on beef cattle production

Laun W. Hall, Samuel Garcia, Robert J. Collier

Research output: Chapter in Book/Report/Conference proceedingChapter

Abstract

Heat stress in cattle occurs when the heat load associated with ambient air temperature solar radiation and humidity exceeds the ability of the cow to dissipate excess heat from work and metabolism. This results in an elevated core body temperature, above the normal physiological range. The primary environmental factors causing the stress are temperature and humidity (measured by the THI index), solar radiation, and wind speed. Heat stress results in disruption of homeostasis, elevated basal metabolism and initiation of physiological acclimation responses. Cattle experiencing heat stress have an elevated body temperature, an increased respiration rate, and decreased feed intake. Insulin production increases and adipose tissues are unavailable for catabolic fuel. Many additional physiological pathways are compromised resulting in a loss of production (growth, reproduction, lactation). Reduced production always has an economic impact. The two major beef production entities affected by heat stress are: cow-calf operations, and feedlots. The ability of animals to adapt to the environment is known as acclimatization and is essential to long-term success of cow-calf operations. In contrast, feedlot populations have a constant turnover in cattle that are often shipped from various climates and sudden changes in environmental conditions can lead to high rates of death loss as animals are unable to quickly alter their metabolism to acclimate to the stress. The ability to acclimate is influenced by breed of cattle. Traits such as hair type, skin pigment, and ability to sweat can precondition cattle for heat resistance. Both short and long term management can reduce the magnitude of climate related stress. In feedlots, fat steers get preferential treatment and location. This group is the most susceptible to heat stress and should receive top priority in hot and humid scenarios. Nutrition is also a tool to reduce the heat load caused by metabolism (heat of fermentation). Feedlots have no natural covering for the ground or shade for the animals that many cow-calf operations benefit from. In beef cattle production, market economics are the driving force for determining degree of environmental protection. Heat stress can decrease milk production in cows resulting in lower 205 day weaning weights, and decrease feed intake and efficiency in a feedlot. Any loss in performance results in a reduced profit. This loss in value provides an estimate of the size of capital expenditure that can be justified to be put towards improvements in facilities to reduce heat stress in future beef cattle production.

Original languageEnglish (US)
Title of host publicationClimatology
Subtitle of host publicationNew Developments
PublisherNova Science Publishers, Inc.
Pages43-62
Number of pages20
ISBN (Print)9781621003229
StatePublished - Dec 1 2012

ASJC Scopus subject areas

  • Environmental Science(all)

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  • Cite this

    Hall, L. W., Garcia, S., & Collier, R. J. (2012). Climatology: The effects of heat stress on beef cattle production. In Climatology: New Developments (pp. 43-62). Nova Science Publishers, Inc..