Physical Sciences and Mathematics Commons^™

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 …