Estimation of Early Growth Rate in the Chicken

Abstract

THE asymetrical sigmoid curve reflects the growth response in poultry as well as in most vertebrate species. Brody (1945) pointed out the difficulties in assuming the linearity of body weight increments when in fact the biological data clearly shows the dependence upon a nonlinear function. His solution to the problem of this non-linearity in the gain of body weight, during the accelerating growth phase, was based on a logarithmic function, which resulted in two distinct estimates of growth rate. When this procedure was applied to chicks, one estimate of growth rate was made for the interval between hatching and three weeks of age and a different estimate of growth rate was made covering the period from three to ten weeks of age. However, the shape of the asymetrical growth curve suggests that one function may describe the accelerating growth phase. This function should reflect growth as being linear from conception…