Tools For a More Ethical and Sustainable Egg Industry

In the egg industry, male chickens are not wanted because they do not lay eggs or produce meat efficiently. Therefore, millions of male chicks are killed shortly after they hatch by gassing or mechanical shredding. This practise raises ethical concerns and has recently been banned in Germany and France. It also consumes large amounts of energy to incubate millions of unwanted male eggs for the three weeks they need to hatch. A more sustainable and ethical alternative to killing male chicks would be to identify them much earlier in their incubation using a molecular sex marker. Ideally, the nervous system of the embryo should be undeveloped at this stage so that the incubation of males can be stopped without the embryo feeling pain. Unfortunately, there is little agreement among researchers about when the developing chicken embryo can first perceive pain. In this project we will: (i) use advanced research techniques to identify the stages at which pain pathways first develop in the chicken embryo; (ii) identify sex-specific (male) markers expressed at this early stage. In work package 1 (WP1) at Leiden University we will study the development of pain pathways in chicken embryos, using spatial transcriptomics, in situ hybridisation, microCT and synchrotron scanning. WP2 (Wageningen University) will use single-nucleus sequencing to track the maturation of pain receptors (nociceptors) in the chicken embryo nervous system. WP3 (Leiden University Medical Center and In Ovo, B.V., B.V.) will use metabolomics to study the development of neurotransmitters associated with functional nociceptors in the chick embryo. They will also screen for novel sex-markers expressed at stages where our data show that the embryo is too young to feel pain. The Dutch company In Ovo, B.V. has a market-ready platform (Ella®) which automatically detects male eggs at nine days incubation. They will license our new ‘pain-free’ sex-specific markers, implement them in Ella and market them worldwide. In return, In Ovo, B.V. will provide co-funding at 14% of the total budget including 10k cash. Our results will be published in open-access articles and in public databases and websites. Our studies on the development of pain pathways will impact other fields where chicken embryos are used, including biomedical research and vaccine production.