Photo Credit: A. Bjurstrom
During extreme cold or hot temperatures, calves utilize extra nutrients to maintain their core body temperature. The temperature range at which a calf uses no additional energy to maintain its core body temperature is called the thermoneutral zone. For a newborn calf, a calf maintains its core body temperature with no additional nutrients from 500 F to 770 F, while a one-month-old calf’s thermoneutral zone is 320 F to 730 F. Any temperature below or above the thermoneutral zone, a calf will begin to utilize the energy consumed through nutrients away from growth and immune system support to core body temperature maintenance. This means fewer calories are used for growth and immune function, and more is diverted to maintaining core body temperature during times below or above the calf’s thermoneutral zone.
The impact of heat stress in pre-weaned calves is generally overlooked, with a focus on the milking herd. Calves are much smaller animals than their adult counterparts, producing less body heat from rumination and having a greater relative surface area for heat loss. However, calves can be impacted by high environmental temperatures affecting health, growth, and animal well-being. As part of the UW-Madison Extension Dairy Program, Fond du Lac County Dairy & Livestock Agent Tina Kohlman developed a fact sheet on “Pre-Weaned Calf Heat Abatement”. There are many low-cost options and best management practices that can be adopted to minimize the impact of heat stress on pre-weaned calves.
- Provide shade
- Reduce stocking density
- Improve airflow and movement
- Access to ample, fresh, cool water
- Maintain clean, dry bedding
- Increase the plane of nutrition
- Offer fresh feed
- Feed calves before and after peak heat and humidity
- Minimize mold, algae, and bacteria growth
- Perform stressful activities during cooler, early morning hours
For additional information on these practices and heat abatement in dairy, please visit https://fyi.extension.wisc.edu/dairy/.