High laying performance and simultaneous high fattening performance in chicken breeding are mutually exclusive due to negative correlations. Currently, roosters from laying lines can only be raised and marketed economically to a very limited extent. Generally, the majority of male offspring are culled immediately after hatching and marketed as animal feed for carnivorous animals. Several methods of in ovo sex determination have been developed to avoid the routine killing of day-old male chicks. Methods such as hyperspectral imaging and analysis of certain components in the allantoic fluid have successfully followed development to practical application in Europe and are already used in commercial hatcheries. Other techniques of in ovo sex determination, e.g. spectroscopic methods, have the potential to end the culling of day-old male chicks. However, to meet industry requirements regarding precision and speed, full automation of the process is required to make these technologies applicable in hatcheries.