Table 3 Sources of variation in cardiac performance. ANOVA models were run using Family, Environment and Family by Environment interaction as the modelled sources of variation. Critical F values for the given degrees of freedom (DF) and the calculated F values are given for Heart Rate, End Systolic Volume (ESV), End Diastolic Volume (EDV), Stroke Volume (SV), and Cardiac Output (CO). Significant F values (p < 0.05) are in bold face and asterisks represent highly significant (p < 0.005) p values.