TABLE 2

Estimated genetic parameters in a population of laying hens

ParameterClassical analysesaEquations 4 and 5
Phenotypic variance13,706b13,725c
Direct genetic variance917***960***
Associative genetic variance132**
DA genetic covariance99 NS
Residual correlation0.12***0.09***
% heritable variationd6.7%20.0%
• Significance levels were obtained from likelihood-ratio tests comparing the full model to the model omitting the term of interest. **P < 0.01; *** P < 0.001; NS, not significantly different from zero; DA, direct–associative.

• a In this analysis, the term ZSaS was omitted from the model (Equation 4).

• b Obtained as .

• c Obtained as .

• d The percentage of heritable variation was , in which was obtained from Equation 2 by replacing true values by the corresponding estimates, giving 960 + 2 × 3 × 99 + 32 × 132 = 2742 days2. (In the classical analyses ).