Estimation of Genetic Parameters for Body Weight in Chinese Simmental Cattle Using Random Regression Model

R Q Yang,H Y Ren,Y C Pan,S Z Xu

doi:10.5713/ajas.2004.914

Abstract

The random regression model methodology was applied into the estimation of genetic parameters for body weights in Chinese Simmental cattle to replace the traditional multiple trait models. The variance components were estimated using Gibbs sampling procedure on Bayesion theory. The data were extracted for Chinese Simmental cattle born during 1980 to 2000 from 6 national breeding farms, where records from 3 months to 36 months were only used in this study. A 3 orders Legendre polynomial was defined as the submodel to describe the general law of that body weight changing with months of age in population. The heritabilities of body weights from 3 months to 36 months varied between 0.31 and 0.48, where the heritabilities from 3 months to 12 months slightly decreased with months of age but ones from 13 months to 36 months increased with months of age. Specially, the heritabilities at eighteenth and twenty-fourth month of age were 0.33 and 0.36, respectively, which were slightly greater than 0.30 and 0.31 from multiple trait models. In addition, the genetic and phenotypic correlations between body weights at different month ages were also obtained using regression model.

Highlights

Simmental cattle were introduced into China at the beginning of last century for improving the Chinese local yellow cattle, which have become the so called ChineseSimmental
In the past two decades, the open nucleus breeding system was established to develop the dairy-beef type Simmental breed so that the body weights became as important as the milk production in the breeding project
The records for genetic evaluation included the real body weights at eighteenth and twenty fourth month of age and the estimated body weights adjusted to eighteen and twenty four months of age. Such genetic evaluation did not take those body weights into account except eighteenth and twenty-fourth month of age, and more estimation error arose from the adjustment of body weights

Summary

Introduction

In the past two decades, the open nucleus breeding system was established to develop the dairy-beef type Simmental breed so that the body weights became as important as the milk production in the breeding project. In practice, only the body weights at eighteenth and twenty- fourth month of age were genetically evaluated using multiple traits model. The records for genetic evaluation included the real body weights at eighteenth and twenty fourth month of age and the estimated body weights adjusted to eighteen and twenty four months of age. Such genetic evaluation did not take those body weights into account except eighteenth and twenty-fourth month of age, and more estimation error arose from the adjustment of body weights.

Objectives

Methods

Results