Table 4. Heritability of CI and the correlation coefficients between CI and AFC with data sets classified by AFC.

Data set	Heritability	Correlation
	Calving interval	Genetic	Phenotypic
≤ 24	0.134 ± 0.027	−0.116 ± 0.060	−0.030 ± 0.014
> 24	0.158 ± 0.020	0.307 ± 0.089	0.054 ± 0.011
Entire set	0.141 ± 0.013	0.250 ± 0.073	0.034 ± 0.009

CI, calving interval; AFC, age at first calving.