Just think through the “levels” of chicken life:
1. Let die naturally of old age 2. Slaughter after a productive life 3. Slaughter mid life because disease 4. Slaughter mid life because money (e.g., price of feed) 5. Slaughter/cull young for sexing 6. Use fertilized eggs 7. Prevent fertilization, use unfertilized 8. Eliminate laying of eggs
Prevention of life is death in the limit.