A NONLINEAR DYNAMICAL (CHAOS) APPROACH TO THE ANALYSIS OF BROILER GROWTH

Mathematical chaos has been observed in a number of biological areas, suggesting that order can be found in systems previously described as random. Nonlinear analyses were conducted to determine whether periodi city or chaos was evident in the growth responses of broiler chickens. Analyses of the absolute growth rate and growth rate acceleration wer e conducted for four lines of broilers selected at 14 or 42 d for high or low growth rates (Experiment 1) and for a commercial broiler strai n (Experiment 2). Resulting Lyapunov exponents (LE) and correlation di mensions (CD) were statistically evaluated. Time series and return map graphics were analyzed. In both experiments, independence of day-to-d ay growth responses was indicated by low r2 values. In Experiment 1, t here were significant differences between lines in growth rate (low, 9 .1 +/- .3; high, 12.9 +/- .5 g/d) and the standard deviation of growth rate (low, 5.8 +/- .2; high 7.3 +/- .3 g/d). There were no significan t differences for LE or CD values between lines or day of selection. I n general, the positive LE, noninteger values of CD, and return map gr aphics in both experiments suggested the presence of chaotic dynamics. Evaluation of mathematical chaos in broiler growth may give insight i nto the dynamics and modeling of growth and diseases associated with g rowth.