Number of Blastodisc Cells During the Laying Period for Two Successive Generations of Layer and Broiler Breeder

In the poultry industry, genetic selection for growth performance is associated with poor reproductive efficiency and an increase in embryo mortality. The identification of new biomarkers is essential to improve these parameters. The blastodisc, composed of blastodermal cells, undergoes cellular events to achieve embryo development. Factors such as hen's age, temperature and time of egg storage could influence the number of blastodermal cells and impair embryo development. In this study, we investigated the variability of the number of viable cells of blastodisc (NVCB) that could be dependent on the stage of laying and on the breed and potentially associated with reproductive parameters. In experimental breeds, eggs were collected during the whole cycle of laying. Then, the protocol was repeated on industrial breeds (breeder hens) during five successive days at three stages of laying (before, after laying peak and at the end of laying period) for two generations (mothers and offsprings). For each egg, the blastodisc was dissected in order to count viable cells. For both experiments, the NVCB increased during the laying cycle. The NVCB was higher in broiler blastodisc compared to layer blastodisc for both generations. For layer breed, the NVCB were negatively correlated with laying rate for the first generation while positively associated for offsprings. However, the NVCB was positively correlated with laying rates in both generations for broiler hens and with fertility and hatchability rates. The NVCB from fresh oviposited fertilised eggs could be a potential tool in predicting on reproductive performances in poultry.