High heritability of egg testosterone and consequences on performance of offspring in Japanese quail

Abstract

DOI: 10.15414/afz.2014.17.04.130–135

Received 4. September 2014 ǀ Accepted 2. October 2014 ǀ Available online 24. November 2014

Individual phenotype is a result of an interacting genotype and environment with the most sensitive periods occurring within the late embryonic and early postnatal development. In this time, most of the signals come from the mother and such influences are termed maternal effects. In our review, we focus on hormone-mediated maternal effects in birds because the avian embryo develops without interactions with neuroendocrine milieu of the mother and the egg yolk contains biologically active substances including hormones. Thus, it is expected that the mother can adjust phenotypic development of her progeny to actual environmental conditions through differential deposition of hormones in the egg. The adaptive value of such hormone mediated maternal effects can have significant consequences for poultry performance but is still generally neglected. In the first part of our review, we summarise the data from wild living birds and urge the need to study maternal egg hormones also in poultry species. In the second part of this review, we present our experimental approach that is based on two genetic lines of Japanese quail divergently selected for yolk testosterone concentrations. We estimated relatively high heritability of yolk testosterone concentrations and proved that natural selection can shape hormone-mediated maternal effects. Our selected lines provided us with a unique model to explore mechanisms of maternal hormone transfer into the egg and epigenetic effects of maternal hormones on offspring. We expect that this approach will provide relevant data in the field of trans-generational maternal effects with potential application for poultry breeding and welfare.

Keywords: maternal effects, hormones, androgens, genetic lines