Using Genetics to Beat the Heat 

August , 2021
 Colleen Larson, UF/IFAS Extension Dairy Regional Agent 

Heat tolerance of cattle in Florida’s environment is a challenge for both beef and dairy producers at temperature continue to climb. Heat stress leads to reduced production efficiency, reproductive failures and health issues. Traditionally, beef producers have addressed these problems with incorporating Brahman genetics while dairy producers have provided heat abatement through mechanical methods, i.e., shade, water, and fans. While these methods are effective, they both have limitations. Researchers are working to provide another tool to help cattle producers fight the heat. They are utilizing the “slick” trait, a mutation in the prolactin receptor gene, that causes cattle to have a very short hair coat year-round. The slick mutation occurred naturally in several breed of cattle in the Carribbean, including Senepol, Carora, and Criollo Limonero. 

Animal Science researcher, Peter J. Hansen, helped develop slick Holsteins and slick Jersey by artificial insemination and embryo transfer. Research at the University of Florida and the University of Puerto Rico has shown that inheritance of the slick mutation minimizes the effects of heat stress on milk yield. In addition, Holstein cows with the slick gene have lower body temperatures, higher sweating rates, and lower respiration rates in a study at the University of Florida Dairy Unit. A larger study is ongoing at dairy farms in Florida and California to evaluate the performance of slick Holsteins in hot and cool seasons.

Holstein heifers

A group of Holstein heifers on a South Florida dairy with the slick gene.

The benefits of genetics from Brahman cattle have allowed the beef industry to thrive in hot and humid environments.  The slick gene may go further to help mitigate heat stress in a segment of the industry where mechanical heat mitigation is not feasible. University of Florida research is currently evaluating the genetic basis for thermotolerance in beef cattle. The goal of study is to develop selection strategies that improve thermal tolerance while maintaining production, reproduction and product quality. UF Animal Science researcher, Raluca Mateescu, is using cattle at the Beef Research Unit and commercial cattle on Florida ranches to develop tools needed to select for thermotolerance traits in beef cattle. Acceligen, a genetic animal science company, has used gene editing technology to produce a slick Angus bull in Brazil.  Current regulations in US prevent this technology from producing food animals but may be accessible in the future to expedite the incorporation of specific thermotolerant genes into beef cattle.

 As our climate continues to get warmer, new methods for keeping cows comfortable will be explored. A combination of environment, genetics and nutrition will be necessary to provide cattle the conditions they need to thrive. Cattle producer’s primary goal of providing heat abatement may be increased efficiencies of production, however the additional benefit of improved cattle welfare and a reduction in carbon footprint could exceed the production returns.

 

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