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Economic impacts of heat stress

Mike Donnelly
University of Minnesota Extension Educator, Rice and Steele Counties

July 28, 2012

Each year we complain about summer heat as if we are surprised by it, but the truth is Minnesota's average high temperatures hover around 80F. As temperatures near 80F people may only feel mild discomfort, but our cows are affected much sooner. As Jeff Reneau explains in the companion article, cows can be stressed at temperatures as low as 72F, or when the temperature humidity index (THI) reaches 68. In order to minimize economic losses caused by heat stress, it is important to be proactive with heat abatement strategies.

Where does heat stress impact your pocket book?

Profitable dairies strive to maximize milk production. However, as milk production and dry matter intake increase so does a cow's metabolic heat output, which increases sensitivity to heat stress (Collier, University of Arizona, 2012). The three main heat stress symptoms driving economic loss are:

Is heat abatement worth it?

As explained above, heat stress can take an economic toll on several areas of the dairy operation. However, given the small number of days that Minnesota experiences high temperatures, is the investment worth it to incorporate heat abatement systems for the dairy herd?

A study completed by Norm St-Pierre (Ohio State University, 2003) evaluated the annual economic impact of heat stress on dairy cows and found that without heat abatement strategies in place, the nation's dairy industry incurred an economic loss of $1507 million. At a Minnesota level, in a year when 34 days exceed the THI threshold, 520,000 dairy cows tally an economic loss of over $27.7 million even with optimal heat abatement strategies. As we apply those numbers to a 150-cow herd, we realize that in an average year Minnesota heat stress contributes to $53.00 in lost income per cow and robs a dairy operation of $7950.

It is important to realize that heat stress can carry more severe penalties depending on the physical location of a herd and its environmental surroundings. Nevertheless, some form of heat abatement is economically justified.

Creating a heat stress management plan:

Keeping the negative economic impact in mind, it is important to be proactive in alleviating heat stress to minimize financial losses. With a number of heat abatement strategies available, developing a heat stress management plan that is both affordable and effective can help keep dairy herds comfortable and with money in their pockets. Consider the following when developing a heat stress management plan:

  1. Adequate air movement. Increasing air movement is an important component to reduce heat stress. Two simple ways to create air movement throughout the barn include adding fans and opening the sides of the barn, and installing nets or curtains.
  2. Availability of water. As the temperatures approach heat stress levels, adding extra water sources is a must. Cows will increase water consumption in heat stress conditions and crowding can occur. Also consider adding sprinklers.
  3. Ample shade. If your herd is kept outside during the summer months, it is essential that you provide shade for them to get out of direct sunlight. If no trees or other natural sources of shade are available, consider adding a netted area as an alternative. Shade over the feeding area will keep cows cool and help with dry matter intake.
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