| Abstrakt: |
The aim of this study was to estimate growth curve parameters of Thalli sheep using different nonlinear models. To achieve the aim, Thalli lambs (n= 130) maintained at Livestock Experiment Station, RakhGhulaman, district Bhakkar (Pakistan) were used to detect the best non-linear model identifying the growth of Thalli sheep. In the present study, seven non-linear regression models such as Gompertz, Brody, Bertalanffy, Monomolecular, Logistic, Richards, and Weibull models were fitted to body weight-age data of Thalli sheep. The most suitable model which determines the growth pattern of these sheep was identified with determination coefficient (R2) and Root of Mean Square Error (RMSE) criteria. The values of parameter 'a', which is the asymptotic weight for all the models, were estimated as: 28.2, 33.1, 28.9, 33.1, 27.1, 28.2 and 28.0, respectively. The values of the turning point (point of inflection), 'b' were 1.304, 1.123, 0.822, 0.165, 2.535, -3.630 and 27.017, respectively. The corresponding values for parameter 'c', which is the growth rate for each model, were 0.398, 0.165, 0.325, 0.701, 0.609, 0.400 and 0.060, respectively. The determination coefficients (R2 %) obtained for these models had a narrow range of 96.8 to 97.9%. Among these models, Gompertz and Richards models produced slightly higher estimates compared to other models in the identification of growth pattern of Thalli sheep. It was concluded that Gompertz model with three parameters would be used for modeling growth curve in Thalli sheep. [ABSTRACT FROM AUTHOR] |
