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Cold stress happens even after the snow is gone

PD Staff Published on 11 February 2013

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Even though the snow and ice may have mostly melted, we can’t forget that calves can experience cold stress at temperatures well above freezing and, therefore, will be susceptible to cold stress for months to come.

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“It’s a common misnomer for people to believe that it has to be freezing for their calves to experience cold stress,” says Dr. Tom Earleywine, technical services director for Land O’Lakes Animal Milk Products . “Calves can in fact experience cold stress at much warmer temperatures.”

Calves less than 3 weeks old can experience cold stress at temperatures just below 60ºF. Calves greater than 21 days old can experience cold stress at 42ºF.

A look at the five-year averages for ambient temperatures year-round across the U.S. show us that 3-week-old calves in Wisconsin and New York could experience cold stress 247 and 243 days of the year, respectively.

And, while it might be easier to accept that calves in Wisconsin and New York are susceptible to cold stress, they aren’t alone. Calves from California could experience cold stress 181 days of the year.

It’s not just newborns either; older calves are just as susceptible. Temperatures show us that calves more than 21 days old could experience cold stress 149 days of the year in Wisconsin, 142 days in New York, 117 in Idaho and 110 in Pennsylvania.

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“It’s crucial that you know the average number of days per year in your state where calves experience cold stress. Don’t be fooled into thinking because you live in a warm-weather state your calves aren’t susceptible,” says Earleywine. “Plan your feeding program to provide the additional energy needed during these cold-stress periods.”

Here’s a look at why
Newborn calves are born with minimal energy reserves. Because calves have a higher surface-area-to-bodyweight ratio than older animals, they become cold-stressed at fairly moderate temperatures.

At temperatures below the thermoneutral zone, calves start to expend their internal energy reserves simply to maintain their core body temperature of 102ºF. The result – energy resources are diverted from growth and immune function, meaning calves will not gain weight and are more susceptible to disease like pneumonia and scours.

The thermoneutral zone for Holstein calves 3 weeks old is 60 to 82ºF but, at temperatures below 60ºF, calves have to increase energy expenditure to maintain body temperature.

As noted earlier, calves older than 21 days old can become cold-stressed at approximately 42ºF, depending on insulation and rumen function. “Consider that, when an 88-pound newborn calf has to start mobilizing its own fat stores to stay warm, it has less than one day’s worth of energy ‘in the bank,’” explains Earleywine.

What can you do?
To help calves survive and thrive, nutrition is the first line of defense. Therefore, implement a feeding program that supports increased energy demand, as energy is the limiting factor to calf performance during times of cold stress.

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• Take a close look at your calf milk replacer. The primary sources of energy in milk replacer are fat and carbohydrates (lactose); both are needed by the calf.

• Feed calves a minimum of two gallons of liquid nutrition each day. Calves fed a “maintenance” diet (less than 1.8 pounds of milk replacer daily) are more likely to fall behind on weight gain and be susceptible to disease.

Lactose provides immediate energy and fat helps to build an energy reserve for the calf. Oxidation of this reserve when the calf experiences cold stress can be the difference between a calf that thrives and one that doesn’t.

• Consider adding a third feeding of milk replacer. Incorporating a third feeding of milk replacer, preferably late in the evening, provides extra energy for young calves.

Research shows that calves fed three times a day have shown improved growth, better feed efficiency, consume more starter prior to weaning and have greater chance of survival to lactation than calves fed twice daily.

So don’t forget, even though most of the snow may be gone, your calves can still experience cold stress for months to come. PD

Click here to download images, including a side bar that takes a look at the five-year average ambient temperature in the top dairy states across the country.

PHOTO
TOP RIGHT: To help calves survive and thrive, nutrition is the first line of defense. Photo courtesy of Land O’Lakes.

—Excerpts from Land O’Lakes Animal Milk Products press release

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