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Minimize heat stress for healthy calves

Luciene Ribeiro Published on 22 May 2015

calf hutches

As the mild spring temperatures creep higher each day, we’re reminded that summer, with its often relentless heat and humidity, is just around the corner. Now is the time to remember that heat stress can be very hard on your calves, but there are steps you can take to keep them comfortable and growing all summer long.

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Know the conditionsfor heat stress

While calves can tolerate slightly higher temperatures than cows, heat stress typically sets in at air temperatures above 80°F, especially if humidity is also high. To keep themselves cool, calves must utilize energy.

Because they don’t have extra energy stored, they must use energy that normally supports the immune system and growth. This shift in resources can slow growth and leave calves defenseless against any pathogens in their environment.

A calf experiencing mild heat stress is much easier to cool than one that is severely overheated. Check your calves regularly on hot days so you can intervene early when you see telltale signs of heat stress, which include:

  • Reduced movement
  • Elevated body temperature
  • Increased respiration
  • Open-mouthed panting
  • Decreased feed intake
  • Increased water intake

Keep them drinking and eating

Your calves should have access to an unlimited supply of clean, free-choice water. Under normal conditions, calves need to drink 1 to 2 gallons of water each day for adequate hydration. When calves are hot, this can increase to 6 gallons per day in addition to milk or milk replacer.

Without adequate nutrients, your calves will not have enough energy to keep themselves cool. To keep a consistent feed intake, offer fresh free-choice starter every day.

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To encourage calves to eat overnight when temperatures are cooler, provide fresh starter and clean fresh water each evening. In the morning, take note of empty grain buckets to see how much was eaten and to determine whether you need to increase the ration.

If your calves still aren’t drinking and eating well despite these measures, try feeding an electrolyte supplement between milk feedings and after the last feeding. Electrolytes can help calves rehydrate more efficiently and may perk them up and help them to feel less stressed. Electrolytes should be mixed with warm water (102°F) and fed between milk feedings to allow for easier digestion and to provide calves with extra fluids.

Sanitation is always important, but it is especially important in hot weather. Regularly clean and sanitize feeding equipment and add bedding as needed to control bacterial growth and fly populations.

Always remember to empty and sanitize grain buckets daily. Milk bottles and buckets should be sanitized following each milk feeding – before using them for water. Sanitation in the milk barn following every milk feeding is also extremely important.

Manage their environment

If your calves are housed in hutches, it is extremely important to remember that the temperature inside a hutch can be much hotter than the outside air temperature. When configuring hutches for summer, place them in high open areas, in the shade if possible, with the fronts facing east to take advantage of natural breezes.

Promote airflow through the hutches by propping up the back edge with cinder blocks. If you’re unable to place hutches in the shade, drape them with reflective hutch covers to avoid heat absorption.

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While you may use straw bedding in colder weather to keep calves warm, its insulating properties are not ideal for summer. Instead, consider sand or sawdust bedding to help keep calves cooler and to help keep fly populations down. To avoid cold stress at night, don’t switch to sand or sawdust bedding until the overnight temperatures in your area are consistently staying above 50°F.

Feed colostrum to every newborn

The importance of feeding high-quality colostrum to every newborn calf cannot be overstated. Calves are born with no immunity against disease, and colostrum provides protection until the immune system matures and begins producing its own antibodies.

Every calf should get a gallon of clean, high-quality colostrum within two hours of birth. Smaller calves that can’t consume a gallon in one feeding can be given 2 quarts within two hours of birth and 2 more quarts within 12 hours.

The heat of summer can affect colostrum quality and quantity, particularly in heifers. Be sure to refrigerate or freeze colostrum if you’re not going to feed it right away, and always test quality with a Brix refractometer or colostrometer before feeding. If quality tests low or if there isn’t enough colostrum to feed every calf, consider using a commercial colostrum replacer or supplement to ensure your calves’ nutritional needs are met.

If you don’t have the ability to chill colostrum immediately after harvesting, you may also want to switch to a colostrum replacer to avoid the risk of bacterial contamination, which can be very harmful to your calves.

Flexibility benefitsyour calves – and you

Perhaps the most important thing you can do when the weather is hot and your calves are stressed is to constantly remind yourself to be flexible. By making some simple changes to your normal routines – like handling or transporting calves early in the morning or late at night when it’s cooler – you can have a tremendous impact on their comfort in the short term and on their growth and performance for years to come. PD

PHOTO
If your calves are housed in hutches, it is extremely important to remember that the temperature inside a hutch can be much hotter than the outside air temperature. Photo byPDstaff.

luciene ribeiro

Luciene Ribeiro
Director of Sales – West
APC, Inc.

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