Non-Linear Models to Fit Nelore Calves Growth Curves from 240 to 600 Days in the Bolivian Tropics

Background and Objective:The growth curves are linked to the growth characteristics and evaluation of the genetic potential of the animals.The objective of this work was to evaluate the growth curves of Nelore calves in the rearing stage (from weaning to marketing) in grazing systems raised in the Bolivian tropics.Materials and Methods: The adjustability of 5 growth models (Brody, Richards, Von Bertalanffy, Logistic and Gompertz) were evaluated.Retrospective data corresponding to the period between 2000 and 2014, belonging to the Agricultural Technological Center Foundation Bolivia, were used, Santa Cruz, Bolivia.Data corresponding to 109 Nelore-weaned male calves were used.For all calves from weaning (240 days), the individual live weight was obtained every 30 days until reaching 600 days in which they were sold, in all the years analyzed.The Brody and Richard models will not be taken into account since they did not converge.Results: The Gompertz, Logistic and Von Bertalanffy models adjusted the weight-age data.With 95% confidence, it can be stated that the asymptotic weight of the calves is between 752.5 and 1194.3 kg according to the Gompertz model, 703.1 and 996.0 kg according to the Logistic model and 796.9 and 1646.9 kg according to the Von Bertalanffy model.In this case, the Logistic model is the one that presented more precise estimates.Conclusion: Of the 5 models studied, only the Gompertz, Logistic and Von Bertalanffy models were adequate to describe the evolution in the weight of calves from day 240 after birth to 600 days after birth.