Amphy is correct. Some vegans who have chickens (often chickens originally intended for commercial egg production) cook and feed the eggs back to their chickens. Hormonal prevention of egg laying hapoens in the form of a device implanted under the skin (like Suprelorin). This is an expensive ($90-$600 a pop), hard to source, and a temporary measure (effectiveness varies from hen to hen and can last from 2 weeks to two years) and is mostly used for hens who are ill and have a higher chance of dying or who have reproductive system issues. Neither the effects of pain involved in laying, nor the effects of hormone use, have been extensively studied. I would love to see more research about this. It is true that there are many species of chickens. In my area, leghorns are used most for egg production because they can begin laying after only a few months and lay up to 300 eggs a year. I'm glad I don't have to lay 300 eggs a year 😅