Table 3. Genetic parameter estimates of the age of first calving with data sets classified by age at calving (24 age month)

Data set	Parameters
	Heritability	Additive variance	Phenotype variance
≤ 24	0.716 ± 0.038	1,517.3 ± 100.7	2,118.6 ± 41.3
> 24	0.087 ± 0.016	337.8 ± 63.5	3,893.7 ± 45.1
Entire set	0.097 ± 0.015	674.2 ± 109.8	6,980.1 ± 66.9