Comparison of Several Models to Fit the Growth Curves of Kıvırcık and Dağlıç Male Lambs


Abstract: This research was carried out to estimate the growth curves of Kıvırcık and Dağlıç male lambs using monthly body weight data from birth to 420 days of age. Fifteen models were compared in terms of growth curve parameters and for the best fit to the data of Kıvırcık and Dağlıç male lambs. Among the linear models simple linear model gave the best fit for Dağlıç and quadratic model for Kıvırcık. However heterogenity was found in terms of regressions equations within each breed and between genotypes. These results say that common regression equation can not be used for all individual in a breed having different growth pattern, not only regression coeffiecient but also mean levels of dependent variable. Among the non-linear models Brody, Negative Exponential, Gompertz, Logistic and Bertalanffy gave quite good fit for the male lambs data. Brody had the highest coefficient of determination.

Keywords: Growth Curve, Lambs, Dağlıç and Kıvırcık breeds, Linear Models, Non-linear Models

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