Table 5.

Heritability and phenotypic SD estimates and P-values for sources of variation

Trait	Year	Dam age	Calf age1	Genotype	h2	σP
Birth weight, kg	0.10	0.001	0.09	0.38	0.68	5.3
Weaning weight, kg	0.91	<0.001	<0.001	0.73	0.30	19.0
Yearling weight, kg	<0.001	<0.001	<0.001	0.99	0.31	24.4
Final weight, kg	0.005	0.001	<0.001	0.85	0.50	48.5
Hot carcass weight, kg	<0.001	0.001	<0.001	0.92	0.42	31.4
Marbling score2,3	0.13	0.60	0.53	<0.001	0.47	34
Ribeye area, cm2	0.004	0.04	0.16	<0.001	0.39	7.1
Adjusted fat thickness, mm	0.15	0.61	0.23	<0.001	0.51	3.2
Vision yield grade4	0.22	0.35	0.10	<0.001	0.52	0.62
Slice shear force3, kg	0.08	0.94	0.34	0.03	0.205	4.0
CIE L* reflectance6	0.03	0.86	0.05	0.01	0.44	1.9

¹Julian birthday linear covariate was used for all traits and is a proxy for age for all traits (except birth weight) because a single harvest date was used each year.

²300 = Slight⁰⁰; 400 = Small⁰⁰ (USDA, 1997).

³Logarithm (base 10) values of traits were analyzed.

⁴Prediction of USDA Yield Grade. Smaller numbers indicate greater yield of boneless, closely trimmed retail cuts.

⁵Constrained to 0.20 ≤ h² ≤ 0.70.

⁶CIE L* measure of lightness. Greater values mean lighter lean color.