Reproductive function in hybrid poultry. IV. An impact of maternal hormones accumulated in egg

Abstract

Deposit of maternal hormones in the egg yolk is shown to significantly change the pattern of ontogenesis in descendants. Accumulation of maternal sexual steroids in yolk influences behavior, growth, morphology, immune function and viability of descendants (T. Groothuis et al., 2005). Testosterone and androstenedione cause changes in postnatal growth (H. Schwabl, 1996), immunocompetence (M.Tobler et al., 2010), models of competitive and agonistic behavior in non-reproductive relationships between individuals (Müller W. et al., 2009) and sexual intercourse (C .Eising et al., 2006). Such consequences develop as a result of regulation of corresponding functions in the descendant body, including indirect influence through other systems. Stress simulation in females by administration of corticosterone (K) led to a dose dependent change in growth and development in the chicken. Imbalance in fatty acids' ratio and assimilation in descendant embryo occurred in the yolk (S. Yalçin et al., 2011) reduce fertility and shell quality, and embryo mortality and death of chicks increase (M. Eriksen et al., 2003; Saino N. et al., 2005; Y.-H. Kim et al., 2014). Similar effects were found in the offspring of hens lines divergently selected by growth rate (A. Abdelkareem et al., 2013). In the yolk of white shell eggs of unstressed layers the corticosterone level is almost two times higher than that in brown shell eggs (K. Navara et al., 2010). Under the influence of different stress factors the activity of the hypothalamic-pituitary-gonadal axis alters, resulting in an inadequate kinetics of sex hormones and inhibition of the reproductive function. Increased concentration of blood corticosterone in the mother hens is accompanied by changes in the content of gonadal hormones in the egg yolk (A. Janczak et al., 2009; F. Guibert et al., 2013), productivity (A. Bertin et al., 2008; E. de Haas et al., 2013) and the sex ratio (S. Correa et al., 2005; T. Pike et al., 2005; S. Pryke et al., 2011). Migration of the hormones form a mother hen to the egg and the embryo, and their interference in metabolism regulation in the descendant occur during early ontogenesis, when the functions of organs and systems are the most labile. Changes in ontogenesis caused by accumulated maternal hormones can be regarded as an adaptive response in the descendants to be ready to a shift in environmental conditions (T. Mousseau et al., 1998; Z. Kankova et al., 2012). Due to egg-deposited maternal hormones the offspring can form phenotypic traits which are inherited epigenetically (T. Groothuis et al., 2008; D. Ho et al., 2011). All these finding should be taken into account at poultry commercial reproduction. When using technological methods and veterinary measures, it is necessary to appreciate possibility of transovarial transfer of signal information about outer conditions mediated by the maternal hormones to cause adaptations in the descendants.