Prediction of genetic trend for milk production in dairy cattle using BLUP technique
2000
Monchai Duangjinda | Manit Tramas | Wisanu Ruamjarern
21,943 milk records from 5,570 cows including with 6,336 animals in the pedigree were used in the analysis. The Calving season and year, number of lactation, days in milk, and level of Holstein breed were treated as fixed effects. Animal and permanent environmental effects were treated as random effects. In this study, genetic variances were estimated by Restricted Maximum Likelihood (REML) and the prediction of breeding value by Best Linear Unbiased Prediction (BLUP) was performed. The relationship between averaged breeding value and year of birth was plotted as genetic trend. Two models using milk yield adjusted for 305 days (Model I) and actual milk yield included days in milk as a covariate in the model (Model II) were compared. The results showed that the estimates for genetic variance for additive genetic and permanent environmental effects were 20.40 percent and 18.07 percent for model I; and 23.30 percent and 18.26 percent for model II, respectively. The prediction of genetic trend showed that the genetic for milk production was improved gradually. Although the genetic trend pattern from both models is not different, model I showed the lower standard error of the estimates and the higher maximum likelihood. This suggested that model I is more appropriate for estimating genetic parameters for milk production in dairy cattle.
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