Document type: scientific review published in INRAE Productions Animales
Authors: Sophie Rehault-Godbert, Marie Bourin, Joël Gautron, Maxime Quentin
Preview: One major problem encountered by the poultry industry lies in the unprofitability of the male siblings of laying hens because of the low meat yield of these strains. This fact, which threatens production ethics, affects 50 million male chicks in France and 7.5 billion worldwide and, until recently, such male chicks were culled after being sexed and sorted at hatching. The public realisation of the existence of this practice, widely publicized in recent years, led to the publication in France of a Decree on February 5, 2022, banning the killing of male Gallus gallus chicks as part of the production of eggs for consumption. Three alternative routes have been proposed since the issue was first examined: 1) to raise the male siblings of laying hens and identify ways to make them more profitable; 2) tp create new genetic crosses between broiler and laying strains, where female offspring would be used for egg production and male offspring for meat ("mixed" strains), and 3) to develop in ovo sexing tools so that male embryos could be detected before hatching and the eggs destroyed. This last approach is the only one that is technically and economically viable, and currently available to the industry. It combines a number of advantages, in terms of feasibility for implementation in hatcheries, and acceptability to consumers, citizens and professionals alike. This review takes stock of the socio-economic context and the in ovo sexing techniques currently available, while providing some facts on the physiology of avian embryology that can help improve understanding of the constraints on the development of techniques for early stages of embryo development.
