Growth curves for ostriches (Struthio camelus) in a Brazilian population

• Grant number: 12/20049-1
• Support Opportunities: Regular Research Grants - Publications - Scientific article
• Start date: November 01, 2012
• End date: April 30, 2013
• Field of knowledge: Agronomical Sciences - Animal Husbandry - Genetics and Improvement of Domestic Animals
• Principal Investigator: Danísio Prado Munari
• Grantee: Danísio Prado Munari
• Host Institution: Faculdade de Ciências Agrárias e Veterinárias (FCAV). Universidade Estadual Paulista (UNESP). Campus de Jaboticabal. Jaboticabal , SP, Brazil

Abstract

The objective of this study was to fit growth curves using nonlinear and linear functions to describe the growth of ostriches in a Brazilian population. The dataset consisted of 112 animals with body weight measurements from hatching to 383 days of age. Two nonlinear growth functions (Gompertz and logistic) and a third-order polynomial function were applied. The parameters for the models were estimated using the least-squares method and Gauss-Newton algorithm. The goodness-of-fit of the models was assessed using R2 and the Akaike Information Criterion (AIC). The R2 calculated for the logistic growth model was 0.945 for hens and 0.928 for cocks and for the Gompertz growth model, 0.938 for hens and 0.924 for cocks. The third-order polynomial fit gave R2 of 0.938 for hens and 0.924 for cocks. Among the AIC calculations, the logistic growth model presented the lowest values in this study, both for hens and for cocks. Nonlinear models are more appropriate for describing the sigmoid nature of ostrich growth. (AU)