As governments and industry move to ban the culling of male chicks, a central question continues to shape public policy, research funding and ethical debates: When can a chick embryo feel pain?

Efforts to observe chicken embryonic development ... However, when fertilized chick embryos immediately after laying (zero-day-old embryos) were cultured using this method, they did not develop ...

While normal chicken embryos develop complex feathers with branches ... They examined embryos at different development stages from day 10 to hatching and followed the chickens for 49 days after ...