When the shopkeeper told you he returns the dead chickens to the company, it could be due to reason the supplier gives a replacement or returns the cost of the dead chicken and he wants to see the dead ones first. I have a shop in the area where I live which sells chickens and the shop owner once told me he makes just three riyals as profit on each chicken he slaughters, cleans and sells. I have never seen this shop having dead chickens lying around possibly because he manages to sell out all of them during the day or he simply dumps them in garbage can whenever such a situation arises.