Sure, the snow and ice are giving way to warmer weather. But a look at five-year average ambient air temperatures suggests calf-shivering cold hangs on far longer than you might think.
Calves can experience cold stress at temperatures well above freezing, contends Dr. Tom Earleywine, technical services director for Land O'Lakes Animal Milk Products. In fact, calves less than three weeks of age can experience cold stress at temperatures just below 60 degrees Fahrenheit. Calves greater than 21 days of age can experience cold stress at 42 degrees.
A look at the five-year averages for ambient temperatures year-round across the U.S., shows that three-week-old calves in Wisconsin and New York could experience cold stress 247 and 243 days of the year, respectively. Newborn calves from California could experience cold stress 181 days of the year, he adds. And, calves greater than 21 days of age could experience cold stress 149 days of the year in Wisconsin, 142 days in New York, and 110 days in Pennsylvania.
Newborns 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 expending internal energy reserves to maintain core body temperature. Their energy resources are diverted from growth and immune functions and are more susceptible to disease like pneumonia and scours.
"It's crucial that you know the average number of days per year in your state where calves experience cold stress," notes Earlywine. "Plan your feeding program to provide the additional energy needed during these cold stress periods."
What you can do
Nutrition is the first line of cold stress defense. So your feeding program must supply enough energy. Here are three measures to consider:
• 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.
• Consider adding a third feeding of milk replacer, preferably late in the evening to provide extra energy for young calves, suggests this nutritionist. Calves fed three times a day show improved growth, better feed efficiency, consume more starter before weaning, and have greater chance of survival to lactation than calves fed twice daily.