Hypothermia (lower than normal body temperature), is one of the major causes of death in newborn calves. With a significant winter storm on the way to Oklahoma this article addresses how to identify, prevent and manage cold stress in baby calves. Moderate environmental temperatures aren’t typically a problem for calves produced by cows with adequate milk/colostrum supply that are in good condition (Body Condition score of 5.5 – 6). Calves from cows that have had good nutrition during the last trimester of pregnancy have a layer of brown fat that serves as a rapidly mobilized energy reserve to make them vigorous at birth and quick to get up and nurse. On the other hand, calves from thin cows may not have the energy needed and are more susceptible to hypothermia. Wet and cold weather (below 50 degrees F) accompanied by wind will take a toll on calves especially if the calving process takes longer than normal. Dystocia (calving difficulty), increases the amount of time a calf will take to stand and nurse, which increases the potential of hypothermia. Calves maintain body temperature by converting food into body heat. Calves need to stand and nurse an adequate amount of colostrum as soon as possible after birth. If there is any question as to whether a calf has ingested an adequate amount, use a tube feeder or bottle to administer warm, high fat (up to 10%) colostrum. A practical rule-of-thumb is to feed 5% to 6% of the calf’s body weight within the first four hours and repeat the feeding when the calf is about 12 hours old. For an 80-pound calf, this will equate to about 2 quarts of colostrum per feeding. Calves that nurse or are given colostrum within the first two to four hours after birth fare much better throughout their entire lives.
There are several ways to assist a hypothermic calf, the first step is knowing when to help. Normal rectal temperature of a newborn calf is 101.5 – 102.5 degrees F. A thermometer will help to know if a calf is at risk. If the temperature drops below 101 degrees F, help may be needed. Place a finger in the mouth to check for a suckling reflex. The mouth of a healthy calf will be warm and moist and the calf will attempt to chew or suck your finger. Lack of a suckling reflex is a definite sign that you are dealing with a cold stressed calf that needs assistance. When calves are cold, the body responds in two ways: shivering and diverting blood flow to their inner core. Shivering is an involuntary reflex that increases heat produced by the muscle, but it requires energy. Excessive shivering, erratic behavior, confusion and clumsy movement are all signs of hypothermia. Mild hypothermia is a calf temperature below 100 degrees F. Severe hypothermia, when internal organs start to cool is below 94 degrees F.
When rewarming a calf is necessary, there are two routes: internal and external. Administering colostrum should be the first step to warm the calf internally. Warm (100 – 102 degrees F), high quality colostrum is vital as it provides fat and energy that will be burned for internal heat. In some cases, administering colostrum or milk replacer may need to be repeated. Externally, the following steps should be followed to treat and prevent hypothermia in at risk calves.
- Dry calves immediately, remove all wetness with towels or a blow dryer.
- Warm externally, use heat lamps, the floor board of your farm truck, a “hot box,” or a warm water bath (around 100°F, gradually increasing). Remove heat source when calf’s temperature is up to 99 degrees F and monitor to ensure they are able to maintain their temperature.
- Get calves off the cold ground, place calves on pallets or blankets to prevent heat loss.
- Get calves to a warm, dry, sheltered area like a barn, garage or shop.
References:
https://beef.unl.edu/beefwatch/2023/managing-hypothermia-newborn-calves.
The Importance of Colostrum. Cow-Calf Corner Newsletter. January 9, 2023. https://extension.okstate.edu/programs/beef-extension/cow-calf-corner-the-newsletter-archives/2023/january-9-2023.html
Mark Johnson, OSU Extension beef cattle breeding specialist, discusses the importance of colostrum during the first 12 hours after a calf is born on SunUp TV from January 16, 2023. https://www.youtube.com/watch?v=red5DqoD8hA&list=PLglOSpV-Tcac6-pVMv0BEAk78_7tJCuap&index=149
