Genetic Evaluation System In China Simmental Cattle

In this study, we elaborated on the whole Genetic Evaluation System of China Simmental cattle. The details of data storage, data cleaning and computing technologies for genetic evaluation were involved. Data storage was mainly based on the Simmental-breeding database we built. The BASE SAS software package was used to implement data manipulation. In this article, we discussed some basic operations that need to be routinely performed to guarantee data quality when dealing with character and numerical data values. And all the SAS Marco codes were listed. The presentation of mixed model methodology for BLUP applications review was intended to be useful for choosing the right statistical methods, including univariate standard animal model, threshold model, generalized linear mixed model and random regression model. The scope is both broad and deep. Finally, the milk flow score and milk production records retrieving from China Simmental database were analyzed. A primary objective of this part was to illustrate how to analyze such data and obtain the estimated genetic parameters. The main findings included the following aspects.1. Establishing the Genetic Evaluation System of China Simmental cattle;2. Building the China Simmental database solution;3. Presenting the methods to perform validity checks on variables to guarantee data that can only take on valid values;4. The ordinal threshold model and Gibbs sampling method were applied to estimate the genetic parameters of milk flow score of China Simmental cattle. The heritability of this trait was intermediate (0.22-0.25). The results suggested that milk flow score that characterize the cows milking ability was a good candidate trait to be evaluated in the selection objectives and showed that the ordinal threshold model was superior to other models for analyzing such data;5. Random regression model was fitted to investigate the mode of inheritance of accumulative milk yield. Genetic analyses of different parities and DIM were carried out for this breed. Variance components were estimated using Gibbs sampling procedure on Bayesian theory. Based on these parameter estimates, heritabilities of 305-d milk yields from 1th to 6th parity were obtained (0.28, 0.30, 0.32, 0.32, 0.32, and 0.31, respectively).