About half of the 4,000 calves on Busse’s Barron Acres in northwestern Wisconsin are on milk in calf hutches, said Sherry Arnold.The operation is dedicated to raising calves from birth to five months for 13 dairies.

In the summer months the calves that are in hutches, as opposed to a weaning barn, are watched particularly closely for signs of heat stress. It’s important to keep heat stress from happening and to address it if it does happen, Arnold said during a June 29 Professional Dairy Producers Dairy Signal webinar.

There are several techniques the farm uses.

First, the hutches are turned to the east at the end of April or in early May. During the winter, the hutches face south, Arnold said, and re-orienting the hutches in the warmer months allows the hutches to cast shade for the calves to rest in during the afternoon hours.

That strategy requires advance planning, Arnold said. A common mistake is producers waiting to long to recognize they have a problem and fix it.

“I can’t go turn 2,000 huts today and face them east,” Arnold said. “I can’t wait that long.”

The calves’ winter straw bedding is also replaced with sawdust bedding in the warmer months. The sawdust improves air circulation, Arnold said. Busse’s Barron Acres also puts wire outside the hutch to give the calves a little space to get out and opens all the vents.

Hutch type is also important to consider. Busse’s Barron Acres uses Poly Square hutches, Arnold said, because they reflect more of the sun’s heat in the summer and tend to be cooler than other brands the farm tested.

“The type of hut, the material definitely makes a big difference,” Arnold said.

Water is always available for calves, and that water is kept refreshed using low levels of chlorine dioxide to keep bacteria levels down and prevent the pails from getting green. During extreme heat, particularly when even nights don’t cool off, they may also provide electrolytes for the calves.

They also haul calves early, ideally by 9 or 10 in the morning. Arnold said it’s a common mistake to pack calves in too tight when hauling them. A trailer might hold 40 calves, but 25 might be a more suitable number when the heat rises.

If all of those steps fail to prevent heat stress and a calf is panting and under stress, workers will pour water over the calf’s core area to help the calf cool down, Arnold said.

“I don’t want to get to that point, but if they do look like that, that’s kind of what we do,” she said.

Calves in a weaning barn seem to have fewer issues with heat stress, Arnold said, with vent tubes running throughout the year and temperature-controlled shade curtains used when the temperature is warmer.

The steps being taken at Busse’s Barron Acres bear similarities to the heat-stress-prevention tactics for calves that are supported by the limited research available on the topic.

“Unfortunately, there’s not a lot of science here, there’s not a lot that’s been published on what is the negative impact of heat stress and how much is it reduced by different things, but there is a little bit of research,” said Geof Smith, dairy technical services veterinarian at Zoetis.

Some of the things thought to minimize heat impact are providing shade, improving air flow, using reflective insulation hutch covers, offering diluted electrolytes and potentially feeding more volume or more frequently, Smith said. For calves that don’t want to eat or drink, feeding early in the morning or later at night might help, too.

In Smith’s opinion, finding ways to improve air flow would be the “most bang for your buck,” followed by offering some electrolytes.

Implementing steps to address calf heat stress is likely to require effort and in many cases money, but they can help avoid the negative effects of calf heat stress.

Among the potential consequences of calf heat stress that Smith listed are reduced growth rates, decreased starter intake, poor immune function, reduced response to vaccinations, increased morbidity and mortality, and negative effects on calf welfare.

The impacts of heat stress in calves might not show up as obviously as they do in cows, where milk production may be impacted, but Smith urged producers to keep calves in mind too when it’s hot.

“Even though you’re not seeing your milk check drop, realize that heat is impacting those calves,” Smith said. “I think everyone realizes heat is impacting the cows, but we forget about the calves.”

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