Growth curve fitting for plateau-type Tibetan sheep

Nonlinear fitting models for growth curves can be used to predict the growth and development rate and changes in the growth curves of livestock. In this study, we fitted early growth and development curves for plateau-type Tibetan sheep using three types of nonlinear fitting model, namely the Gompertz, Logistic, and Von Bertalanffy models. The results showed that the growth of plateau-type Tibetan lambs could be well fitted using the three growth curve models (R² > 0.99). Among the three models, the fitting effect of the Von Bertalanffy model was found to be better than that of the other two models. The age in months and weight at the inflection point, as well as the best gain of ram lambs were 1.35, 12 kg, and 246.67 g·d⁻¹, respectively, whereas those for ewe lambs were 1.36, 11.96 kg, and 239.33 g·d⁻¹, respectively. The growth curves for the early growth and development stage of plateau-type Tibetan sheep established using the Von Bertalanffy model can provide a theoretical basis for early selection and breeding.