| Abstract |
The objective of this study was to determine the appropriate order of Legendre Polynomial Function (LPF) using in Random Regression Model (RRM) to estimate genetic parameters of Test Day Milk Yield (TDMY). A total of 147,620 TDMY records from 16,947 primiparous crossbred Holstein-Friesian cows throughout Thailand were analyzed using 9 RRMs, which varying orders of LPF 3-5 nested within both Additive Genetic (AG) and Permanent
Environmental (PE) random effects. Restricted maximum likelihood was used to estimate variance components. The results base on coefficient of determination (R2), negative 2 log likelihood (-2logL), and Residual Variance (RV) revealed that, there was insufficient to improved performance of RRM with increasing order of fit. The RRM with highest order of LPF, i.e. RRM(5,5) showed oscillatory patterns with larger additive genetic variances,
heritability, but lower genetic correlations between 65 and 125 days in milk than the rest. However, oscillatory pattern reduced, when PE had higher order of fit than AG. This would suggest that, the RRM(3,5) with order 3 for the AG and 5 for the PE is the most appropriate model for genetic parameters estimation of TDMY of primiparous crossbred Holstein-Friesian dairy cattle in Thailand. |
Publication
Journal Publication
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