The recent below-normal temperatures in eastern North Dakota could have negative impacts on this spring's calf crop into the fall weaning season, North Dakota State University Extension Service livestock specialists warn.
This year, producers who calve in large pasture settings are having newborn calves born in conditions that are 10 to 20 degrees colder than normal.
"Newborn calves leave the safe and uniform temperature of their dam's uterine environment and enter the outside world with temperatures and weather not always conducive to life," says Gerald Stokka, NDSU Extension's livestock stewardship specialist. "Exceptional animal husbandry skills are necessary to provide the care needed for newborn calves to deal with the cold spring calving season and to prevent health problems later on."
Neonatal calves have two internal mechanisms to help them cope with cold weather. First, calves are able to shiver, which is the involuntary muscle movements designed to increase warmth by expending energy. The second mechanism is the nonshivering response, which allows fat to be used to increase the calves' metabolic rate by two to four times their resting rate.
"This is a special kind of fat and differs from white fat in that this brown fat is readily available to the newborn to provide energy to cope with the sudden change in the calf's environment," Stokka says. "Calves born to properly fed dams come equipped with this remarkable cold-coping mechanism."
The newborn calf's ability to cope with cold weather means the calf will rise quickly after birth and find its food and life source through the dam's colostrum. Colostrum is a form of milk that mammals produce in late pregnancy.
It contains energy, protein, fat and vitamins, plus antibodies to protect newborns against disease until their own immune system is totally functional.
In colder temperatures, calves born without some environmental protection or born to mothers with poor-quality colostrum will be at greater risk for infection from disease-causing pathogens, NDSU Extension veterinarian Charlie Stoltenow cautions. These may be pathogens that cause calf scours or are associated with respiratory disease.
"In either case, the pathogens are simply taking advantage of a calf with a compromised immune status," Stoltenow adds.
Here are ways producers can minimize the risk of disease:
* Provide extra bedding for pregnant cows.
* Watch for calves that are cold and slow to get up. Cows that are delivering calves usually leave the herd and find secluded locations in which to deliver their newborn.
* Provide cold calves with some type of additional heat. This may mean placing the calf in a "hot" box or moving it to a warmer, out-of-the-wind environment for a few hours.
* Give calves suffering from severe hypothermia a warm-water bath. Dry heat may not work well enough to warm calves in this condition. For more information on calf warming, visit http://tinyurl.com/calfwarming.
* Ensure that calves receive adequate colostrum because supplemental heat alone will not warm the newborns.
The dam's colostrum is optimal. The next best options are frozen, stored colostrum or one of the commercial colostrum substitutes, according to Stokka.
The commercial colostrum substitutes need to contain a minimum of 100 grams of immunoglobulin G (IgG) per packet. IgG is an antibody absorbed through the calf's small intestine and provides protection against disease-causing pathogens.
Cold-stressed, immune-compromised calves also may require a little extra care with vaccination protocols. In populations of immune-compromised calves, a significant number of them may not be responding adequately to vaccination procedures.
"Booster doses - that is, second and third doses given within a defined time frame - may be more important this year to prevent respiratory disease during the summer and fall weaning season," Stoltenow says.
Calf vaccination research at NDSU's Central Grasslands Research Extension Center indicates that vaccine doses given 90 days following the initial spring turnout dose acts as a booster to increase protection against the bovine respiratory syncytial virus and Mannheimia hemolytica respiratory pathogens.