As regards time trends, the Franklin model [ 25], suggesting three phases in variance components for growth traits (juvenile, mature and adult phases), was tested in different species [ 26- 28].
The two tailed Student's t-test for was applied for IHC quantification and the two-way analysis of variance for tumor growth experiments with the post hoc multiple comparison Bonferroni test.
Only five loci, Growth1, 4, 6, 9 and 10, reached genome-wide significance for at least one body-weight or growth trait and none explained more than 4.4% of the residual variance for a growth-related trait (Table 3).
In contrast, the reported number of smoked cigarettes per day had an increasing effect (P=.034), accounting for 6% of the variance of growth hormone secretion.
For example, Corey et al. (1976) found that maternal effects accounted for more variance for five early growth traits in a diallel analysis than did the GCA and SCA effects.
LCGA is a type of growth mixture modelling where the variance and covariance estimates for growth factors within each class are fixed to zero, assuming homogeneity within classes.
The ratio of the genetic variance to the phenotypic variance was found high to moderate for growth, feed intake, and RFI (VG/ VP = 0.63 ± 0.11, 0.29 ± 0.11, 0.29 ± 0.09, respectively).
We showed that the models can capture a large proportion of the genetic variance from dominance and epistasis for growth traits as those components are typically not independent.
Studies in other species such as quail [ 10], pigs e.g. [ 11] and poultry, e.g. [ 12, 13], have shown that social interactions between animals may be responsible for a substantial part of the heritable variance for traits such as growth and survival.
