Milk Replacer

Five Calf Heat Stress Challenges and How to Beat Them

Calf : Cold & Heat Stress

Animal : Calf

Tom Earleywine, Ph.D.

Director of Nutritional Services

Hot weather can wreak havoc on young calves. When temperatures rise above 78 degrees F, calf respiration rates increase, potentially leading to dehydration, reduced feed intake, weaker immune system, heat stress, calf scours and other calf health issues.1

Here are five challenges your calves might face during hot weather and tips to help overcome them:

Challenge 1: Increased dairy calf nutrition needs

Calves will burn more energy in high temperatures as they try to lower their body temperature. With more energy used for cooling measures, calves have fewer nutrients available for growth.2 Feeding calves a high level of nutrition can help them continue growing while also meeting their energy needs during heat stress.
Tip: Feed a full potential diet of 2.5 pounds of milk solids in 8-12 quarts of milk or calf milk replacer per day. Consider adding a third feeding as an easy way to increase calf nutrition levels without increasing volume at each feeding. Research suggests calves fed three times a day have optimal growth, better feed efficiency and consume more starter before weaning.3

Challenge 2: Calf health issues

Warm weather promotes the growth of bacteria and disease organisms, such as Cryptosporidium and Salmonella, as well as algae and mold. An increase in bacteria can increase the risk of calf health issues.
Tip: Cleaning and sanitizing feed equipment will help keep bacteria populations down and will also help with fly control. Clean and sanitize pails, bottles, nipples and other mixing and feeding equipment after every feeding. Empty and clean water and starter pails at least twice a day. Keep bedding fresh and provide adequate drainage, especially around feeding and water areas.   

Challenge 3: Dehydration

One of the first signs of heat stress in calves is dehydration. As respiration rates go up, calves expel more water through the air to try and cool their bodies. Calves can double the amount of water intake to help them handle heat stress and stay hydrated.
Tip: Offering free-choice calf electrolytes during high temperatures is a great way to increase fluids, improve hydration and help prevent calf scours. Mix calf electrolytes with water and feed after every, or every other, milk or calf milk replacer feeding. Never mix electrolyte powder with milk or milk replacer.
Calf electrolytes aren’t a replacement for water. Offer water free-choice daily. Empty and refill water pails at least twice a day to keep water fresh. Switching to five-gallon pails or adding an extra water source for group-housed calves can help increase drinking. Water quality is also critical. Test water quality at least twice a year to make sure it’s low in sodium (<50 ppm), iron and other minerals. 

Challenge 4: Fly control

Calves are hot spots for flies. Buzzing flies are not only annoying but can spread diseases such as bovine virus diarrhea (BVD), the bovine herpesvirus (BHV-1) causing infectious bovine rhinotracheitis (IBR), parainfluenza 3 (PI3), pink eye, mastitis, calf scours, typhoid, anthrax, vibriosis and several clostridial diseases.
Tip: Feed a calf milk replacer and starter that includes a feed through larvicide or supplement with a fly control additive. Start feeding a fly control product 30 days before flies begin appearing to help reduce fly populations and prevent disease spread. Continue feeding throughout the summer and fall until 30 days after the first frost.4 Evaluate areas surrounding your calves to identify and address other potential fly hot spots (e.g., tall grass, proximity to lactating herd, spoiled feed, manure storage).

Challenge 5: Calf starter feed intake

Maintaining starter intakes can be a big challenge during high temperatures. Starter feed intake drops when calves are hot, which can cause a reduction in average daily gains.
Tip: Reducing the fat level in calf milk replacer can help drive starter intakes. But contrary to popular belief, low fat doesn’t equal low energy. A 100 percent increase in fat alone in the diet may only yield a 12 percent increase in energy. Alternatively, a 50 percent increase in calf milk replacer powder with balanced fat and carbohydrates can generate a 50 percent increase in energy.5
It’s all about balancing fat and protein to provide calves with the energy needed for respiration and cooling in warm weather while encouraging calf starter feed intake. Choose a milk replacer designed for warm temperatures to provide balanced nutrition and help calves eat more starter.  
Prepare your calves for any challenges Mother Nature might throw at them with LAND O LAKES® Cow’s Match® WarmFront® calf milk replacer.  

1 Leadley, S., Attica Veterinary Associates, Calving Ease, July 2008, Tips for Hot Weather Management
2 Broadwater, N.R., Keeping your calves cool and comfortable in the summer, University of Minnesota Dairy Extension
3 Feeding calves three times a day delivers benefits, Facts based on 2011 research: D. C. Sockett* 1, C. E. Sorenson 2, N. K. Betzold 3 , J. T. Meronek 3 , and T. J. Earleywine 4, 1 Wisconsin Veterinary Diagnostic Laboratory, University of Wisconsin, Madison, 2 United Cooperative, Sauk City, WI, USA, 3 University of Wisconsin-Madison, College of Agricultural & Life Sciences, Madison 4 Land O’Lakes Inc., Cottage Grove, WI
4 Stevenson, D.E. and Cocke, J., Extension association; Extension entomologist; The Texas A&M University System; Integrated pest management of flies in Texas dairies, 2000
5 National Research Council. 2001. Nutrient Requirements of Dairy Cattle: Seventh Revised Edition, 2001. Washington, DC: The National Academies Press.