Chicken white egg chemerin as a tool for genetic selection for egg weight and hen fertility

Abstract

Embryo mortality rate, which can reach up to 40% in avian species, is a major issue for breeding. It is therefore important to identify new embryo development biomarkers for genetic selection to improve reproductive performances. We have recently shown that chemerin is expressed in the oviductal hen magnum, accumulates in egg white, is correlated with embryo survival and could thus be used as a molecular marker of embryo development. Eggs from seven hen breeds (n = 70) were collected during five successive days at the end of the laying period. After weighing eggs, yolk and albumen, an egg white sample from each egg was collected and a blood sample was taken from each hen. Chemerin concentrations in albumen and blood samples were measured by a specific home made ELISA assay. Hen’s plasma and egg’s albumen chemerin levels were found to be correlated with reproductive parameters such as fecundity, fertility, embryo mortality, hatchability and laying rates. The inter-hen chemerin level variability in albumen was higher than intra-hen except for one breed (R+). We observed significantly different levels of chemerin in egg white between breeds. However, chemerin concentrations in egg white were not significantly associated to variations of hen plasma chemerin levels. Interestingly, we observed negative correlations between albumen chemerin concentrations and egg weight (r = −0.43, p = 0.001), between albumen weight (r = −0.40, p = 0.002), and between yolk weight (r = −0.28, p = 0.03). We also showed negative correlations between egg white chemerin concentrations and fecundity (r = −0.32, p = 0.011) and fertility (r = −0.27, p = 0.04) whereas no significant correlation was observed with the laying rate. Taken together, these results suggest that egg white chemerin concentration might be a good biomarker for genetic selection for egg weight and fertility in hens, provided these data are confirmed on a larger scale.

Adipokines expression in reproductive tract, egg white and embryonic annexes in hen

“…In addition, the adipokines and their receptor are also expressed in the oviduct in mammals. In hen, the authors showed that chemerin concentration in egg white produced by the magnum is negatively correlated with egg performances (egg weight, albumen weight, and yolk weight, Bernardi et al, 2022 ). However, they did not observe significant correlation with the laying rate.…”

Expression of chemerin and its receptors in extra-embryonic annexes and role of chemerin and its GPR1 receptor in embryo development in layer and broiler hens

“…Chemerin concentrations were measured from amniotic and allantoic fluids and plasma of eggs incubated by using enzyme-linked immunosorbent assays ( ELISA ) as previously described by Bernardi et al (2022 , 2023 ). The recombinant chicken chemerin protein (full length, rRARRES2) was obtained from the Gallus gallus sequence (NM_001277476.1), produced in Escherichia coli and purified by a chromatography column-based on His-Tag under denaturing conditions (Agro-Bio, La Ferté Saint Aubin, France).…”

“…Proteomic analyzes have also identified the presence of chemerin in the egg white and perivitelline membranes of chicken eggs ( Mann, 2007 , 2008 ). We previously showed that chemerin in egg white comes from a part of oviduct named magnum ( Bernardi et al, 2022 , 2023 ; Estienne et al, 2022 ). During the early embryo development, chemerin system is also present in extraembryonic annexes such as allantoic and amniotic membranes and fluids, suggesting a passage of chemerin from the egg white to the embryo annexes and more specifically in the amniotic fluid ( Geelhoed and Conklin, 1966 ; Yoshizaki et al, 2002 ; Estienne et al, 2022 ).…”