Growth curve estimation in pure goat breeds and crosses of first and second generation in Tunisian oases

摘要

Five non-linear statistical models were tested to fit the growth curve parameters of the kids of indigenous, Alpine and Damascus goats and their crosses. Data from 16 years’ periodical weight study was used to adjust the growth curve of 1,687 suckling kids before they attained the age of five months. Among the tested models, the iterative procedure made it possible for the Gompertz model to be identified as the best for use to adjust kids’ growth evolution. Brody, Richards, Logistic and Polynomial models showed some convergence problems of accuracy. Curve parameters were fitted by Gompertz model after about 16 iterations with a?coefficient of determination (CD) value of 71%. Growth parameters were established by genetic groups and the shape of the curve changed with kids’ genotypes. Crossbreeding allowed for a better growth kinetic in indigenous kids. After birth, kids’ weights increased rapidly to an asymptotic weight at an early age. The best growth performances were obtained in the first generation of crossbreeding due to heterosis. The growth curve adjustment helped in better flock management and in the fattening of kids according to the potentialities of each genotype.