A common reference population from four European Holstein populations increases reliability of genomic predictions

Table 3 Validation of parent index (PI) and genomic breeding values (GBV) using Dutch/Flemish (NDL_ref) and EuroGenomic (EU_ref) reference populations

Trait	Number of bulls			Dutch/Flemish reference				EuroGenomic reference
	NLD_ref	EU_ref	valid	REL_PI	b₀/σ_g	b₁	REL_GBV-PI	REL_PI	b₀/σ_g	b₁	REL_GBV-PI
Protein yield	3471	9618	1115	0.25	0.02	0.99	0.23	0.24	0.01	0.94	0.28
Udder depth	3468	9541	1113	0.19	-0.04	1.00	0.19	0.19	-0.05	1.01	0.36
SCS	3458	9604	1107	0.29	-0.05	1.04	0.19	0.29	-0.06	1.06	0.27
ICF*	3472	9398	1117	0.35	0.09	1.03	0.18	0.33	0.10	1.03	0.21
Average	3467	9540	1113	0.27	0.01	1.02	0.20	0.26	0.00	1.01	0.28

*ICF: interval between calving and first insemination; REL_PI: r²_{(PI, DRP)}/REL_DRP, DRP is deregressed proofs in the validation dataset, REL_DRP is the average reliability of DRP; REL_GBV-PI: the difference between REL_GBV and REL_PI, where REL_GBV is r²_{(GBV, DRP)}/REL_(DRP); b₀ is intercept and b₁ is regression coefficient of DRP on GBV; σ_g is the genetic standard deviation

ISSN: 1297-9686