EVALUATION OF FOUR CLASSICAL NON-LINEAR MODELSTO DESCRIBETHE GROWTH CURVE OF FUNAAB-ALPHA CHICKENS

摘要

The study assessed four non-linear models (Gompertz, Logistic, Bertalanffy and Richards) to describe the growth performance of FUNAAB-Alpha chickens (FAC). Three hundred (300) FAC chicks of both sexes were raised from day old until the 20th week of age. Body weight records were taken weekly and the NLIN procedure of SAS was used to fit the four non-linear growth models. For all the models, parameter A (or asymptotic weight) ranged from 2050.8 to 3716.6g for the male and 1591.7 to 3330 gfor the femalechickens respectively, while Parameter B, the scaling parameter (constant of integration) ranged from 0.7541 to 15.441. Similarly, Parameter K (maturity index) ranged from 0.0463 to 0.2002. Parameter A was highest for the Bertalanffy model while the Logistic model estimated the highest values for Parameter B and Parameter K. For all the models fitted, age at inflection point ranged between 13.30 and 17.63 weeks for male chickens and 14.23 and 19.94 weeks for female chickens, while the corresponding body weights at inflection point ranged between 754 and 1528g and 586 and 1261 g for male and female chickens respectively. Using the Akaike Information Criterion (AIC) and Bayesian Information Criterion (BIC) as the goodness-of-fit criteria, the Bertalanffy and Gompertz growth models were selected as the best fit models for evaluating the growth of FAC.