USAgNet — Severe winter weather places stress on livestock herds that can dampen their immune response and lead to potential losses.
South Dakota Cooperative Extension Veterinarian Russ Daly said the prolonged stress of weather events like the recent sub-zero temperatures and blizzards across the state can cause problems that show up even after the weather improves.
“Wet, snowy weather combined with severe wind chills can produce stress that increases cortisol levels, which in turn dampen immune response,” Daly said. “This makes livestock, especially in young animals, more susceptible to a number of respiratory and digestive pathogens.”
There are some immediate dangers to the health of animals from severe cold, like chilling and frostbite, Daly said, but also problems that may not be apparent until 7-14 days following the event.
“Calf pneumonia due to respiratory pathogens like Mannheimia hemolytica, Pateurella multocida, and Haemophilus somnus usually shows up 7-10 days following a stressful period or heavy pathogen exposure,” he said. “In young calves, scours organisms like rotavirus, coronavirus, and cryptosporidia are potential problems, and can manifest in a week or less.”
Heavy exposure to pathogens, such as when high numbers of animals are brought indoors, or when the stress is higher, can shorten incubation periods for these illnesses, Daly said.
“In most cases, there’s little vaccination can do after the fact, so prompt identification of sick animals is essential,” said Daly. “Calves or lambs with respiratory infections often respond to antibiotic and other treatments that herd veterinarians would recommend.”
Daly said weather stress combines with other stresses animals may encounter, such as weaning, transporting, and processing.
“Producers must consider winter conditions in light of management decisions. Anything that can be done to reduce weather stress to livestock should be considered carefully,” he said. “If processing, transporting, and weaning can be delayed until severe wind chills and wet, snowy conditions have subsided, they will reduce risks and losses.”
Daly said local veterinarians are the best sources for animal health information in adverse conditions. “No one else is more qualified to answer prevention and treatment questions in light of conditions on the ground in your area,” he said.
South Dakota Cooperative Extension Beef Specialist Cody Wright said that the predicted low temperatures, following last week’s heavy snows, should remind all producers to follow a few key steps to prevent losses or damage to herds.
“Protect the cattle from the weather as much as possible, and since the stress is related to wind chill, providing wind breaks is important,” Wright said. “Additional bedding is also recommended.”
Wright said the general rule of thumb is that for every degree Fahrenheit the temperature drops below 32 degrees, producers should increase their herd’s diet energy by 1 percent.
“This rate is based on the effective ambient temperature or wind chill index, and in many cases, cows will adapt to the cold stress by increasing intake, so an ample supply of long-stem forage is essential,” said Wright. “However, under more extreme conditions, like negative wind chills or wet conditions, it may also be advantageous to provide a better quality forage and/or small amounts of grain, up to 0.25 percent of body weight.”
Alternative feeds such as soybean hulls and DDGs will also work, Wright added.
