Chickens grow very fast, especially with the artificial diets they are fed. It is only a couple of weeks before they are slaughtered as that gives the most optimum food to weight ratio. Remember that the larger something gets, the less it grows and the more energy is wasted moving. This is also why chickens are often stored in "batteries" so they move even less and grow faster.
Chicks are also subject to industrial processing. Any that are sick, small, mutant or wrong gender will be destroyed. The gender determination process is also highly dangerous for young chicks and it is said that the people who do it kill hundreds at first before they learn to do it properly.
Especially when producing egg laying chickens there is a huge wastage of chicks. All (well as good as) have to be destroyed since they are of no use for human consumption (different gene stock needed meat chickens). This is where gender selection is applied and it is literally like female, pass on, else kill.
What I am surprised is that humans are still involved in the process. Modern automated systems are far more efficient for such purposes and will remove any human contact from it. However I guess such plants would not be economical for chicken processing as the value of chicken is so low compared to the high cost of an autonomous plant for the purpose that it will never pay back.
Chicken is not very healthy to eat anyway nowadays. About 30-40% of what they eat is recycled chicken (the killed chicks/left overs from butchering/feathers) with the rest consisting of hormone/chemical supplements and soya. There is very little actually healthy in a chicken and that is why it has virtually no flavour and tastes like watery meat. I would strongly recommend people to eat more Turkey meat as they cannot be treated as inhumanly as chickens (they die more easily) so are more nutritious and also more flavourful.
