Effect of lameness on lactation curves of Vrindavani cattle

Abstract

The present study was aimed to find the best lactation curve model that describes the milk production pattern of Vrindavani cattle suffered from lameness. In the present study, daily test day milk yield data of Vrindavani cattle suffered from lameness were collected from cattle and buffalo farm, LPM section, ICAR-IVRI over 5 years (2009-2014). Eight lactation curve models [Inverse quadratic polynomial model (ND), Incomplete Gamma function (WD), Linear decline model (CL), Wilmink model (WL) Mixed log model (ML), Mitscherlich x Exponential (ME), Morant and Gnanasakthy model (MG) and Ali & Schaeffer lactation curve model (AS)] were fitted and parameters were estimated by nonlinear regression using PROC NLIN procedure of statistical package SAS 9.4. The best model was selected based on different goodness of fit criteria and the result shows that the Mixed Log (ML) model was the best fitted to describe the lactation pattern of Vrindavani cattle suffered from lameness. The Durbin-Watson test was used to check the presence of autocorrelation present in the data set, whereas, Kolmogorov-Smirnova test and Shapiro-Wilk was used to check the normality of the residuals.