Cold Stress in Calves

Written by Dr. Vicky Lauer, Professional Services Veterinarian at ANIMART

Once again, cooler temperatures are on the way, and now is the time to prepare. To help calves perform to their full genetic potential, several steps must be taken to help them overcome cold stress.

Cold stress occurs when a calf expends energy to stay warm. This diverts energy away from growth and the immune system, thus compromising weight gain and calf health. For calves less than three weeks of age, cold stress begins at 60°F, and for every one-degree drop in temperature below 50°F, a calf requires 1% more energy just to stay alive. Even more energy is required for growth. Calves over six weeks of age don’t begin to feel cold stress until temperatures fall below 42°F. Rain, snow and wind will further exacerbate cold stress if there is not adequate protection from the elements. Newborn calves are the most susceptible to cold stress due to their low body fat and minimal grain intake, so an increase in scours and pneumonia is very common during the colder months.

An effective way to manage cold stress is to provide more calories. One option is to increase the amount of milk at each feeding. A benefit of this is the feeding schedule remains unaltered. The problem is very young calves may not want to drink the additional milk, thus starving them of essential energy. An alternative is to add a third feeding. This feeding should be the same volume as the other two feedings, increasing the caloric intake by one-third. With regards to the interval between feedings, as long as the timing is consistent, the calves don’t necessarily have to be fed every eight hours. Beneficial results can be attained by feeding at 6 am, 12 pm, and 6 pm, but other schedules can be equally successful.

Other nutritional options involve adding more milk replacer powder or fat to the milk. By adding extra milk replacer powder, while keeping the volume of water the same, you increase the fat and protein content of the milk. The calf will consume the same volume of milk (for example, 2 quarts), but there will be 12 ounces of powder instead of the standard 8-10 ounces.  Adding a fat supplement by itself will increase the energy density of the milk to a greater extent than adding milk replacer powder, as fat provides more calories than protein. Whether you add more powder or only fat, the total solids of the milk should not exceed 16%, as a higher total solids level can dehydrate the calf if free-choice water is not available.

It’s not uncommon to see calves eat more starter when it is cold. Too often this is driven by hunger due to an insufficient amount of milk offered. A balance is needed between milk and grain consumption. One benefit of higher starter intake is faster rumen development. The heat generated by the rumen bacteria acts as an internal furnace, warming the calf from the inside out. As starter intake increases though, the amount of water the calf requires also goes up, so warm water must be provided multiple times a day to prevent freezing. Many studies have shown calves grow best on milk though, so more emphasis should be placed on milk consumption than grain.

Other cold stress management techniques focus on the calf’s surroundings. Calf jackets are an excellent way to decrease the amount of heat a calf loses to its environment. The calf must be completely dry before a jacket is put on so it doesn’t trap moisture against the calf. Long-stem straw is the ideal bedding and should be deep enough to enable a calf to nestle in for warmth. The calf’s entire foot and at least part of the leg should be covered with bedding to provide proper insulation. Bedding should always be kept clean and dry, as wet bedding robs more heat from the calf.

Following these simple steps will minimize cold stress and equip the calf for a lifetime of success.

Do you have questions or comments about winter cold stress in calves? Feel free to add it to this post.

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