Modelling the Growth Curve of Nigerian Fulani Ecotype Chicken under Two Production Systems

Résumé

This study modeled growth curves of Nigerian Fulani ecotype chicken (NFEC) under two production systems with four non-linear growth functions. The main objective was to establish growth descriptors for NFEC. Two hundred (200) day-old chicks of NFEC were obtained from an established population stocks of the Teaching and Research Farm, OAU, Ile-Ife, Nigeria. The chickens were separated randomly to intensive and pastured poultry production systems at 12 weeks of age. Data on body weight were taken weekly. Data were analyzed using PROC GLM of SAS^®. Four non-linear growth functions including Gompertz, Logistic, Bertalanffy and Richard’s models were fitted using the NLIN procedure of SAS®. Results showed a significant effect of sex (P<0.05) from 10th to the 21stweek of age, while significant interaction effect (P<0.05) was observed between sex of chicken and production system at weeks 16 and 18 (P<0.05). Results of growth modeling showed that parameter A values (asymptotic weight) were significantly different for both sexes for all the models (P<0.05), with higher values for males. Gompertz and Bertalanffy models emerged as the best fit functions for NFEC based on goodness-of-fit tests. Growth curves of the chickens in the pastured poultry system were not significantly different from those in the intensive system (P>0.05). The inflection age predicted with Gompertz and Bertalanffy for male chickens was 13^th and 10^thweeks respectively.