Mathematical models for estimating the rabbit body weight

Abstract

A method was used to adjust the data of rabbit body weights to logistic and Gompertz curves for explaining the growth (y) as a function of age in days (x). This method consists of the following steps: fixation of horizontal asymptote (y = a) from the data: transformation of weight y = In [(a - y)/y] for logistic and y = In In (a/y) for Gompertz, in order to make a linearization of curves; adjustment of the linear regression by least squares (Ŷ = A + BX) and the use of the inverse transformation for estimating the logistic ŷ = a/(1 + b^x) and Gompertz ŷ = ab^cx functions. The approximate methods provided excellent adjustment (for Gompertz specially), with determination coefficients beyond 0.98 and with small differences between the observed (y) and estimated (ŷ) data. The ease of calculation makes the proposed method very useful, mainly in case of lack of computers for determining the estimates a, b, c by interative methods.