
On-farm data can drive your heat abatement strategy
While impossible to avoid heat stress altogether, the type of housing we offer dairy youngstock can influence their ability to cope. What setup is optimal to keep calves cool on your operation? The Vita Plus calf heat risk audit could help you find out.
How is the audit conducted?
The objective of the audit is to quantify a farm’s seasonal, environmental and animal outcomes for dairy calves in the summer. Measurements are used to categorize the farm’s overall heat stress risk and can help provide guidance on management, housing, and nutrition factors that contribute to or prevent heat stress.
The audit is conducted during two farm visits. Weather loggers are placed to monitor housing temperature and air speed while consultants measure calf respiration rate and rectal and skin temperatures. Five years of historical seasonal data are collected from the closest local weather station. The results are tabulated and compared against expected ranges, ranked from “minimal” to “severe” heat stress risk. Each section of the scorecard is weighted to give a final heat risk score. Additional data are provided to dairies on daily temperature variation and housing comparisons (if multiple housing types are offered on-farm). An example report can be found here.
What has the audit taught us so far?
Data from participating farms over the past two years tells us that:
- Housing type influences environment and calf outcomes (Figure 1, click image to enlarge).
Indoor housing promotes a cooler microclimate for calves. Of participating farms, ambient temperatures were on average 1 degree Fahrenheit cooler inside a barn, whereas calf hutches were roughly 2 degrees Fahrenheit warmer compared to the outside temperature. This is likely driven by the shade block from barn roofs and elevated ventilation rates. Air speeds were elevated indoors (0.9 versus 0.1 meters per second) from the placement of barrel fans and positive pressure tube ventilation. However, the improved environmental outcomes from indoor housing did not translate to benefits in calf responses. No particular housing category led to a noticeable improvement in calf respiration rates or rectal temperatures.
One specific housing group did have noticeable negative outcomes – translucent poly hutches. The lack of both ventilation and shade block made these housing structures susceptible to elevated internal temperatures and calf thermoregulatory responses. If this is the type of housing you currently offer, see the second point for modification strategies.
- Calf heat stress abatement strategies make a difference (Figure 2, click image to enlarge).
Regardless of housing type, enhancements can be made to level up heat abatement. This is particularly true for farms housing calves in hutches. Farms that offered both shade and ventilation to hutches (either translucent poly or standard plastic) saw improvements in hutch internal temperature and reduced calf respiration rates and rectal temperatures compared to non-ventilated, non-shaded hutches.
Shading hutches can be accomplished by placing 80% to 100% shade block cloth over the top of hutches, either by draping the cloth or adding a pole-based structure. Passive ventilation is achieved by opening hutch doors and/or propping up the rear of the hutch using slim pieces of wood or piping. Target air speeds should be around 0.3 to 1.0 miles per hour.
What does this mean for you?
As the summer heat continues to drag, consider your own operation. How are calves faring this summer? Is your housing optimized to cool them down when temperatures rise? Benchmarks for heat stress can be found in this accompanying Starting Strong video.
Briefly, calves should:
- Maintain milk and starter intakes
- Consume water
- Thermoregulate normally (i.e., respiration rate under 60 breaths per minute).
If any of these areas are lacking, consider adding shade and/or additional ventilation to your current housing structures.
If you’d like to better understand the heat stress risk for your calves and discuss potential housing strategies, reach out to your Vita Plus consultant to schedule your own calf heat stress audit.
Category: |
Animal health Facility design Heat stress Starting Strong - Calf Care |