Our results suggested a significant additive genetic effect of the GnRHR gene on traits
of egg number and egg mass. Chickens with genotype of AA significantly produce more eggs
than other genotypes, which was followed by more egg mass production (Table 5). However,
no significant differences were observed among genotypes at the phenotypic level (Table 5).
Dunn et al. (2004) found a significant association between GnRHR gene and the number of
double-yolk eggs in a commercial broiler breeder hen population. Dominance effect of this
gene on egg number in Wenchang chicken was reported by Wu et al. (2007). GnRHs are
mainly associated with the development and function of the reproductive axis in avian species
(Bedecarrats et al., 2006). Also, GnRH and its receptor therefore begin the cascade that produces
the appropriate growth, maturation and maintenance of the gonads (Dunn et al., 2004).