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Statistical Considerations When Using Hysteresis To Estimate Internal Heat Load In Dairy Cows, S. Maynes, A. M. Parkhurst
Statistical Considerations When Using Hysteresis To Estimate Internal Heat Load In Dairy Cows, S. Maynes, A. M. Parkhurst
Conference on Applied Statistics in Agriculture
Water is often used to manage heat stress in dairy cattle. Sprinklers are often placed over the feed bunk or used while cattle are waiting to be milked, however in this experiment cattle were given control over water with a cow-activated shower. Previous studies have focused on how wetting can lower body emperature or reduce respiration rates. An alternative way to investigate this management practice is to examine internal heat loads. Internal heat load can be quantified by fitting a hysteresis loop to daily field data. The hysteresis loop is formed by a phase diagram of body temperature versus an …
Estimating Area And Lag Associated With Thermal Hysteresis In Cattle, F. Yang, A. M. Parkhurst
Estimating Area And Lag Associated With Thermal Hysteresis In Cattle, F. Yang, A. M. Parkhurst
Conference on Applied Statistics in Agriculture
Thermal hysteresis in cattle becomes visible when the phase diagram of body temperature (Tb) vs ambient temperature (Ta) exhibits a loop. The hysteresis loop shows a rotated elliptical pattern which depends on the lag between Tb and Ta. The area of the loop can be used to quantify the amount of heat stress during thermal challenge. Three methods to estimate the area and lag of the elliptical hysteresis loop are: linear least squares method, ellipse-specific nonlinear least squares method, and Lapshin’s analytical method. Linear least squares method uses residual least squares to estimate the coefficients of the ellipse for which …
Characterizing Thermal Hysteresis In Body Temperature For A Heat Stressed Steer, F. Yang, A. M. Parkhurst, D. A. Spiers, J. B. Gaughan, T. L. Mader, G. L. Hahn
Characterizing Thermal Hysteresis In Body Temperature For A Heat Stressed Steer, F. Yang, A. M. Parkhurst, D. A. Spiers, J. B. Gaughan, T. L. Mader, G. L. Hahn
Conference on Applied Statistics in Agriculture
Studies have shown that exposure of animals to a high ambient temperature environment poses serious threats to their health, performance and productivity. Above a certain threshold an animal's body temperature (Tb) appears to be driven by the hot ambient temperature (Ta). For steers challenged by heat stress, the Tb-Ta relationship shows a dramatic increase in Tb per unit change of Ta and the dynamics of the Tb-Ta relationship follow a pattern which depends on whether Ta is increasing or decreasing. A delay becomes noticeable in a steer’s thermo-regulatory response to Ta when Ta is controlled to be sinusoidal in the …
Evaluating Pen-Day Interactions In Body Temperature Bilogistic Mixed Model For Handling Of Feedlot Heifers During Heat Stress, F. Yang, A. M. Parkhurst, T. M. Brown-Brandl, R. A. Eigenberg, J. A. Nienaber
Evaluating Pen-Day Interactions In Body Temperature Bilogistic Mixed Model For Handling Of Feedlot Heifers During Heat Stress, F. Yang, A. M. Parkhurst, T. M. Brown-Brandl, R. A. Eigenberg, J. A. Nienaber
Conference on Applied Statistics in Agriculture
Daily activities consume the energy of heifers, subsequently causing an elevation of body temperature, depending on the ambient conditions. A better understanding of the dynamics of body temperature (Tb) would be helpful when deciding how to process and handle heifers. It would also lead to specific recommendations on moving heifers under different ambient conditions, especially during the summer. In this study, a bilogistic mixed model is used to describe the dynamics of Tb during the moving event. Data was taken from heifers in pens located at different distances from the heifer work station on four separate summer days under hot …