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A model of thermal acclimation in cattle
Journal of Animal Science
|August 1, 1985
Summary
A new model accounts for cattle acclimation and short-term thermal stress (STTS) to predict feed intake. This approach offers a more accurate understanding of how fluctuating temperatures affect cattle behavior and nutrition.
Area of Science:
- Animal Science
- Environmental Physiology
- Agricultural Engineering
Background:
- Classical models often overlook the dynamic acclimation state of animals to thermal environments.
- Short-term thermal stress (STTS) significantly impacts animal behavior and physiological responses, including feed intake.
- Understanding these factors is crucial for optimizing livestock management and welfare.
Purpose of the Study:
- To develop and validate a novel model predicting cattle daily feed intake.
- To incorporate the time course of thermal acclimation and behavioral responses to STTS.
- To differentiate the model from classical intake-temperature models by including the animal's acclimation state.
Main Methods:
- Developed a model representing physiological acclimation via a running average temperature.
- Defined STTS as the difference between acclimated and current daily mean temperatures.
- Derived an empirical relationship for daily feed intake (I) based on environmental temperature and acclimation state: I = 100% - b'[Ti - Tacci(L)]².
- Determined acclimation period length (L) and behavioral response coefficient (b') for various cattle breeds and feeding situations.
Main Results:
- Cattle breeds showed variations in acclimation period length (L) but not in the behavioral response coefficient (b').
- Feeding situation (feedlot vs. free-roaming) significantly affected b' but not L.
- The model's explicit treatment of acclimation and stress provides a more meaningful thermal environment representation than mean daily temperature alone.
Conclusions:
- The developed model offers a more nuanced understanding of temperature effects on cattle feed intake by considering acclimation and stress.
- This model has potential applications in interpreting both laboratory and field studies, acknowledging the influence of experimental timeframes on animal acclimation.
- The findings suggest that a two-dimensional representation of the thermal environment is superior for fluctuating conditions.