Um....just stopping by to add my two cents worth.
I have a LF Cochin, Harry. He has been at the bottom of the pecking order since birth. He is so gentle and sweet. Took me forever to figure out if he was a boy or a girl. He did not have rooster behaviors....at all. Until one day...when he finally grew up much later than the others and decided he wanted a girl friend. The head rooster did not take it well and they got in a fight. I really can't stand the fighting and had room to build him a corner in the run where he would not get beat up.
I can tell you he was sad. He looked sad. Acted sad. For weeks. Then I started the search for him some girls. I wanted them to be cochins but could not find any.....posted, searched and called everyone I knew that has chickens. Finally I found some up by my mothers and made the trip and had a visit with her and stopped on the way home to pick up my new girls. THEN got home and the next morning realized that the chickens that I did not load into the crate were two hens and two roosters. Well......Harry has his two girls and is a new boy. He even started crowing.
Could I see a difference in his behaviors. Yes. He was lonely for the flock he was raised with. He was very sad about it. Still there is one of the hens that comes around the corner to visit with him several times a day. There is one place where it is hardware cloth instead of tin and they cluck and visit with each other.
I am like the others that say it is not the same as we feel....but they do feel. They get scared, excited, lonely and sad. Not on the same level with us I am sure but on a chicken level, yes.