Calves Get Heat Stressed, Too

May 29, 2012 08:13 AM

Source: Land O’Lakes Animal Milk Products

 As temperatures start to climb and cause you to perspire – don’t forget your calves are also feeling the heat.
When we think of heat stress our thoughts often go to the lactating herd first, as heat and humidity can have a dramatic impact on milk production and therefore have a potential impact on our pocketbooks. But there are also plenty of economic reasons to be concerned about heat stress in calves, says Tom Earleywine, technical services director for Land O’Lakes Animal Milk Products.
There is very little hard data that indicates exactly when a calf will become heat stressed. Industry consensus estimates heat stress occurs between 78° to 80°F in calves. When temperatures rise above 78°F the calf begins to sweat and respiration rates increase.
Consequences of increased respiration rates and sweating are rapid dehydration, reduced feed intake, a weaker immune system and the internal body temperature of the calf rises – which is never good. In addition, the calf will burn more energy as it tries to drive heat from its body and it is likely that fewer of the nutrients that are consumed will be put towards growth.
Heat stressed calves are also more likely to have a slower rate of gain which means they might not reach breeding size in a timely manner. As a result, age at first calving could be pushed back. If a calf becomes too stressed from heat, it can die.
“Management strategies from greater calf housing ventilation, shading calf hutches, providing free choice electrolytes, increasing water and feeding frequency to evaluating the technologies in the milk replacer fed can help to alleviate heat stress in calves,” says Earleywine.
What can you do? To help calves not only beat the heat but also thrive in warm weather conditions, consider the following management ideas.

Offer free choice water. Empty and refill water pails several times throughout the day to offer fresh water. It should not be a surprise for calves to double their water intake. Switching to five-gallon pails may also be helpful.


 Clean and sanitize water and milk pails frequently. Warm weather promotes algae, mold and bacteria growth. Keeping water and milk pails clean and sanitized will help keep these populations down, as well as help with the fly population.

• Evaluate milk replacer formulas. Be sure to provide a high level of nutrition to calves so they can grow to their full potential and meet their energy needs as they struggle relieve heat stress. Transitioning to a calf milk replacer formulated for warm weather can result in greater feed efficiency and bottom line potential. New milk replacer formulas provide the optimal protein-to-energy balance as temperatures moderate and are designed to meet the specific needs of the calf.
•  Consider adding a third feeding of milk replacer. Research shows that calves fed three times a day have shown optimal growth, better feed efficiency, consume more starter prior to weaning and have greater chance of survival to lactation than calves fed twice daily.
• Provide free choice electrolytes. High quality electrolytes with suspension agent mixed properly can be free choice fed during heat stress.
• Keep calf starter fresh. Calf starters can go bad in hot weather, so it’s important to make sure the feed is kept fresh. Note that molasses, a common calf starter ingredient to aid in palatability, can be a tasty attractant for fly populations. Newer calf starters use alternative natural palatability enhancers with minimal molasses.
• Provide shade. Make sure to provide calves plenty of shade in hot weather.
• Evaluate calf handling. Consider changing the time of day when handling calves is done. Routines that were fine for cold weather might not be the best for the calf in warm weather.
• Get a handle on flies. Unfortunately calves are a hot spot for flies. Using a milk replacer and a calf starter that includes a feed through larvicide can help to keep the fly population down. A reduced fly population may also reduce stress to the calf and the spread of diseases by flies.
As temperatures rise, don’t forget that when you start to perspire so do your calves. Take steps now to help them beat the heat.
For more information on warm weather calf milk replacers or how to incorporate a seasonal feeding program into your herd, visit or call 800-618-6455.
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