LACTION CURVE IN BROWN SWISS CROSSES IN THE REGION OF AZUERO

Abstract

Five mathematical models of lactation curve were evaluated in the region of Azuero and the influence of some fixed factors over the parameters that describe the lactation curve. The models used were: incomplete gamma or Wood, Linear, Quadratic or Dave, Nelder and Bianchinni and Sobrinho. The fixed factors evaluated were, genotype, calving season and parity number. Marquadt method was used to calculate the parameter models. The decision judgment was the maximum value of adjusted multiple coefficient of determination (R²_aj) and the minimum value of mean square errors. Finally, a mixed model was used for the determination of the influence of the fixed factors, over a, b and c parameters in the shape of the lactation curve. From the evaluated models, the quadratic or Dave model show the best adjustment with 5,6127 of mean square errors and 0,9284 R²_aj. The genotype and the calving season were a meaning influence the lactation curve parameters.