Comparison of different lactation curve models of holstein cattle raised in a private farm in Kirsehir province

In this study, six different lactation curve models were compared by using test day milk yield records belonging Holstein cattle raised at a private farm in a Kırşehir province between 2014 and 2015. For this purpose, to identify the best lactation curve models of Wood, Cobby and Le Du, Exponential, Parabolic exponential, Quadratic, Logaritmic Linear mathematical functions were used. Estimation of lactation curve parameters were obtained by STATİSTİCA statistical program. The coefficient of determination (R2) and residual standard deviation (RSD) statistics were used for determination of best fitted model in lactation curve. Wood function is the best goodness of fit model as having the highest R2 and lowest RSD coefficients. The coefficient of determination (R2), residual standard deviation a, b and c parameters for Wood model were estimated as 91.87%, 0.123, 22.86, 0.188, 0.045 for first lactation; 93.31%, 0.166, 23.44, 0.219, 0.06 for second lactation; 91.42%, 0.099, 21.58, 0.172, 0.035 for third lactation; 95.31%, 0.065, 22.25, 0.195, 0.044 for forth lactation; 89.66%, 0.167, 22.13, 0.202, 0.044 for fifth lactation and 99.0%, 0.468, 23.74, 0.067, 0.02 for all lactation, respectively. As a result, the parameters are estimated by Wood model, for use in breeding programs in this herds will be made an important contribution to research in this field. Key words: Lactation curves, Holstein cattle, adjusted multiple coefficient of determination and residual standard deviation