Chemerin concentration in egg white in layer and broiler hens during the laying period for 2 successive generations

Abstract

The genetic selection progress in layers and broilers makes poultry production one of the fastet growing industries. Objectives of the breeding companies are the stability or the increase in the laying rate and the production of viable chicks. New biomarkers are necessary to improve reproductive and egg performances. Chemerin (Chem) produced by oviduct accumulates in egg white (EW). Here, we hypothesized that EW Chem concentration was dependent on the stage of laying and on the breed (layer vs broiler). In addition, they could be associated to laying performance and fertility parameters. In breeding companies, we collected during two successive generations (G0 (mother) and G1 (daughter)) eggs from 100 layers and 100 broilers hens during five days at three stages: before, after laying peak and at the end of laying period. For each egg, the EW was sampled to measure Chem concentration by ELISA assay. In each generation at the end of laying period, magnums from oviduct, where the EG is formed, were collected in layers and broilers in order to investigate Chem differential expression by RT-qPCR between both breeds. Chem concentration in EW was dependent on the time of laying period and its profile was differently regulated in layers and broilers. Indeed, it increased at the end of laying in layers whereas it decreased after the laying peak in broilers. At the end of laying period, Chem concentration in EW was almost two-fold higher in layers than in broilers and this was confirmed in both G0 and G1 generations at the Chem mRNA and protein levels in the magnum. For the two successive generations, Chem concentration in EW was negatively correlated with the laying rate and the fertility parameter in broiler hens whereas it was negatively correlated with the egg quality (weight of whole egg and weight of albumen) and positively with the fertility rate at some time of laying in layer hens. Taken together, the Chem concentration in EW could be a potential predictive tool for reproductive parameters in genetic selection.