Physical Sciences and Mathematics Commons^™

Spline Models For Estimating Heat Stress Thresholds In Cattle, A. M. Parkhurst, D. A. Spiers, G. L. Hahn

Conference on Applied Statistics in Agriculture

Studies of the relationship between animal body temperature and air temperature suggest body temperature is essentially unresponsive until a threshold is reached, then it responds dramatically to increasing air temperature. The goal is to estimate the threshold between the thermoneutral plateau and the beginning of the heat stress challenge. One approach is to fit a polynomial to estimate the knot position and use spline functions to perform linear least squares piecewise polynomial fitting. Another alternative is to use nonlinear regression to estimate the knot or an inflection point of a nonlinear function. In both approaches the cyclic nature of body …