Hybrid one-step genomic evaluation system for the Italian Simmental breed

Abstract

The One-step project is a collaboration between ANAFI, ANAPRI and ANARB whose objective is to develop a system of joint genetic-genomic evaluations for bulls, cows and young animals, for all traits. A hybrid one-step procedure was developed in which single trait animal model deregression of domestic cow and bull EBVs as well MACE EBV is followed by single-step genomic evalutation using the deregressed EBV as phenotypes. The system was initially built around SNP-BLUP evaluations, optionally including or excluding cows from the training set, as a transition step and for comparison purposes. There were not big differences between SNPBLUP and ONE-STEP for the productive traits in term of reliability gain, while the difference was larger for SCS and conformation traits. Increase of reliability of GEBV due to the inclusion of the cows in the reference population was limited in general. However, in the future, the inclusion of genotyped cows and genotyped foreign bulls with MACE evaluations is essential for breeds like Italian Simmental that have a relatively few genotypes and many foreign bulls with few or no daughters in Italy.