The age at which farm animals are slaughtered affects both the duration of their welfare experience and the specific welfare challenges they face during their short lives.
The age at slaughter determines how many welfare experiences an animal accumulates during its lifetime and which welfare challenges are most significant. Broiler chickens slaughtered at 6 weeks experience only the welfare challenges of rapid growth, housing conditions, and slaughter itself - but they experience nothing else. Dairy cows slaughtered at 5-6 years have experienced multiple pregnancies, lactation cycles, and potentially years of chronic health problems before culling. Bobby calves slaughtered within days of birth experience only birth, separation, transport, and slaughter. The welfare significance of early slaughter is that animals have very little time in which welfare improvements can be experienced - making the conditions during their brief lives, and the method of slaughter, the critical intervention points.