Growth curves for Ile de France ram lambs raised in feedlot

The objective of this study was to evaluate the nonlinear models that best describe the growth curve of ram lambs Ile de France created in intensive system in the state of Paraná. Therefore, there were weighed fortnightly during the period from February 2013 to June 2013, from birth to slaughter (120 days) of 31 Ile de France ram lambs. Growth curves were obtained by nonlinear models Brody, Von Bertalanffy, Gompertz and Logistic in which parameters were considered maturation rate (K), asymptotic weight (A), age of the animal (t) is given by integration determining the proportion of growth after birth (B) and the proportion of asymptotic value at which the inflection point occurs curve (m) in accordance with the adopted model. The parameters were estimated by Marquardt applied to the NLIN procedure of SAS statistical program and the criteria used to verify the accuracy of the fit of the curves were the mean square of the coefficient of determination. The Brody, Von Bertalanffy, Gompertz and Logistic resulted respectively in 26.4579; 26.1668; 26.136; 26.1582 for the mean square and 0.813; 0.958; 0.958; 0.958 for the coefficient of determination. Considering the criteria assumed the Gompertz model, followed by Logistic and Von Bertalanffy, presented the best fit to describe the growth of Ile de France ram lambs.