Comparative study of growth patterns in seven strains of Japanese quail using nonlinear regression modeling

Abstract

The aim of this study was to compare the growth pattern of seven strains of Japanese quail including Wild, Italian Speckled, Tuxedo, Scarlett, English white, White button, and A&M Texas by nonlinear growth functions including Gompertz, Richards, logistic, Lopez, and Weibull functions. The body weights of the unselected randomly bred populations of these strains were measured weekly from 1 to 42 days of age and then used to fit functions. The fitness of each function was assessed by statistics including the mean square error, Akaike information criterion, Bayesian information criterion, and adjusted coefficient of determination. The results showed that Gompertz was the best function for describing the growth curve in Italian Speckled and Wild strains; however, the best function for the other strains was the logistic function. The maximum and minimum values for age and weight at the inflection point were obtained for the White button and Scarlett strains, respectively. The weight to age ratio at the inflection point was maximized for Italian Speckled. The best growth rate was observed for the Italian Speckled strain, whereas the White button strain exhibited the worst growth rate. In conclusion, the Italian Speckled strain had the best properties among the tested strains for breeding as broiler poultry.