Heat stress can set cattle up for respiratory issues


Cattle suffering from heat stress will go off feed and, in some cases, become more susceptible to respiratory disease. Using just a few tactics to reduce the effects of hot weather will help keep cattle healthy and productive.

“We are seeing a lot of heat stress in cattle late this summer,” reported Taylor Engle, DVM, with Four Star Veterinary Service in Chickasaw, Ohio.

“Cattle will really back off feed and drink more water when heat stressed. You also may see them standing around in a wet spot in a dry lot, or with a frothy mouth and panting. At that point, you are in a tough spot.

“The biggest things cattle need are good air quality, clean water, dry bedding and plenty of shade in dry lots for good husbandry…and more water availability,” he added.

Add shade to dry lots

Most of the cattle Engle works with are either in dry lots or in smaller feedyards with a retrofitted dairy barn or lean-to facility. Cattle can become stressed in both situations if not managed correctly.

For dry-lot cattle, Engle recommends putting up inexpensive shade cloths to provide some protection from the sun.

“Shade cloths are designed to allow cattle feeling the heat to get under some shade,” he explained. “Then they can bounce back and forth between the feed, shade and water. It’s also a good way to increase feed intake during these hot, stressful times.”

Air, quality bedding in barns

A renovated barn can pose other problems especially if the cattle are kept confined with no access to an outside yard.

“A lot of these barns lack good ventilation so that exacerbates heat stress,” Engle said. “It gets hot; the bedding quality is poor, and humidity increases. Cattle will tend to congregate together which makes the situation worst because they will continue to produce more manure in a single spot which exacerbates the ammonia and humidity in the barn.”

Engle calls this mixture a recipe for disaster. “The ammonia from the urine and manure damages the cilia in the respiratory tract and reduces the animal’s ability to breathe out pathogens. We see a huge increase in respiratory disease when cattle are kept in these types of facilities.”

The best solution is to use a dry lot or yard with these barns. Engle suggested keeping the cattle in the barn during the hot daytime and pushing them outside at night where they breathe fresh air. This practice also will reduce the amount of manure ending up in the barn, which is another advantage.

Electrolytes, water, feed

“The other thing I focus on with heat stress is preventing dehydration,” Engle said. “When cattle get dehydrated, their mucus thins out, and they need fluid to cough up pathogens. It also allows things like leaky gut syndrome to occur because the normal immune functions of the calf are gone. It becomes a wildfire and is hard to get ahead of it.”

His advice to prevent issues with dehydration is to run electrolytes in the water whenever it gets hot, especially over 90° F.

“If it’s already hot, you should be running electrolytes to help calves increase water intake,” he said. “It’s cheap insurance.”

In addition, always provide plenty of water for the cattle. “I’ve never been to a farm where I said there’s too much water, or we had to provide less water availability,” he said.

“It’s also best to increase feed intake during these stressful times,” he added. Calves tend to eat more when shade and plenty of water are also provided in a hot dry-lot environment.

How to improve a young calf’s future performance

The first few weeks of a calf’s life are the most important for developing a healthy animal. “Everything we do for calves in the first 6 weeks will dictate how they perform for the rest of their life,” stated Taylor Engle, DVM, with Four Star Veterinary Service in Chickasaw, Ohio.

“And in the first 10 to 14 days, if a calf has a really bad experience and can’t get through it, it will struggle for the rest of its life,” he added. “The chance of that calf hitting its true potential is limited whether as a beef animal or as a heifer replacement.”

Engle suggests several steps to take for providing the best care possible to help young calves grow into healthy, productive animals.

Good plane of nutrition

The first step in a calf’s life is making sure it starts off with adequate colostrum from a cow that has been vaccinated.

“Not all colostrum is created equal,” Engle said. “It’s what we put into the cow before she creates her colostrum that is important. Vaccinating a cow before she calves will allow her to increase the amount of antibodies she puts into her colostrum and dramatically benefit the calf.”

He also wants colostrum intake measured and the colostrum quality determined with a refractometer. “So really focus on good colostrum management, and make sure those calves have good colostrum intake,” he said.

After colostrum, follow up with a good milk replacer that mixes well and is easily absorbed by the calf. As the calf grows, it also develops an active immune system, which takes a lot of energy. And if the calf is stressed, it will need more energy. “If we stress a calf, it’s going to need a good plane of nutrition,” Engle said.

In addition, provide only good, clean, fresh water for calves so they will drink plenty of it. “If a farmer won’t drink out of the bucket, we shouldn’t ask the calf to drink out of it either,” he said.

Super-clean environment

The next step is to ensure calves have a “super-clean environment,” Engle said. “But a lot of dairy beef producers struggle with disinfection. If we put a calf in a hutch or pen that hasn’t been disinfected, that calf will have a problem if there was a calf before it that had scours. The animal will get the disease and continue to pass it along to the barn. Make sure to disinfect the entire calf area.”

In addition, bottles used for feeding should be completely disinfected between calves to reduce disease pressure.

Good bedding maintenance

Quality bedding is important for good calf health. Engle prefers straw bedding over other types including sawdust, which can lead to respiratory problems. Straw bedding allows the calves to nest and keep warm in cold weather.

Good bedding, and not just straw bedding, will help decrease naval infections. “If a calf’s naval gets infected, it will translocate to the liver, and the animal will be systemically ill which causes lots of challenges,” he added.

Calf bedding must be kept clean and changed on a regular basis to help reduce stress, which increases a calf’s need for more feed.

“Always keep good clean bedding because in the winter it’s a warmth provider,” he continued. “In summer if the bedding is not changed, it will get moist and will have flies and bacteria growing on it, which are detrimental to calf health.

“It takes time to do a good job with bedding,” he added. “Some things we have to do with these calves are not convenient.”

Disease prevention

Baby calves are at risk of developing scours or respiratory disease, which threatens to upend their health for a lifetime. In the first few weeks, Engle focuses on enteric pathogens including the parasite cryptosporidium, bovine coronavirus and rotavirus, and bacteria including E. coli, clostridium and Salmonella.

“Definitely disinfection will help reduce the environmental disease pressure,” he said. “Water is important too, because as these calves have an enteric challenge, they will scour and become dehydrated. We have to have calves hydrated to prevent certain diseases and stay healthy.”

Taking steps to ensure newborn calves stay clean, warm, hydrated and fed will go a long way to producing healthy animals for future markets, according to Engle.