Panting is considered a robust animal response indicator of heat stress in feedlot cattle; however, continuous visual monitoring is impractical on a commercial scale, according to researchers in Australia who recently evaluated an automated sensor system for panting detection.

Publishing their research in the journal Animals, researchers Md Ashraful Islam, Sabrina Lomax, Mohammed R. Islam and Cameron E.F. Clark with the University of Sydney in Australia and Amanda K. Doughty with Allflex Australia Pty Ltd., said current thermal indices are good predictors of heat stress at a herd level but have limited application at the individual level.

Islam et al. validated an ear tag-based sensor for monitoring panting in cattle and determined the individual variability in panting duration for heat stress events, comparing it with existing thermal indices. Sensors were able to monitor differences in cattle panting due to breed, coat color and individual variability.

They noted that heat stress causes significant economic losses by reducing the productivity and welfare of cattle while requiring a significant investment in resources for heat mitigation.

Islam et al. used an accelerometer-based ear tag sensor to monitor cattle panting and determine individual variability in heat stress responses with reference to thermal indices.

They conducted two experiments: Experiment 1 validated the sensors, while experiment 2 determined individual variability comparing sensor data against thermal indices.

Ear tag sensors were fitted at feedlot entry to continuously monitor the behavior of 100 steers of mixed breed in experiment 1 and 200 steers and heifers of mixed breed in experiment 2, Islam et al. explained.

Sensor-derived "heavy breathing" was validated against visually observed panting scores, the researchers said. Sensor-derived behavior bouts were analyzed as "raw," and single behavior states were also converted to the preceding bout of more than two minutes -- referred to as "fill" data for the validation study.

Islam et al. said their results demonstrated the sensors’ ability to accurately monitor panting in feedlot cattle. The sensor-recorded heavy breathing duration per animal was highly correlated to observed panting duration for both raw (r = 0.89) and fill (r = 0.90) data; however, the concordance correlation coefficient was lower for raw (0.45) than fill (0.76) data, the researchers reported.

According to Islam et al., experiment 2 demonstrated that the duration of panting increased from 0800 to 1700 hours alongside changes in thermal indices, with significant differences among and within breed and coat color categories of cattle, suggesting that grouping and allocating heat amelioration measures by breed and coat color can be effective in commercial feedlots.

On the other hand, there was high variability (coefficient of variation greater than 80%) in the duration of panting among individuals within the same breed and same coat color, Islam et al. said, which shows the potential for strategic management at an individual level and, with the same data, genetic selection for heat resilience.