There are many good books on the subject. I believe I recommended "The Pig that Sang to the Moon" earlier as farmed animal specific. Alex the parrot has an excellent biography written by his trainer called "Alex and Me" that explained when putting together a scientific thesis about animal behavior not much of the animal's personality shows through. This lends further to the idea that animals are little more than Descartian instinct machines and can...corrupt the interpretation of the data in some ways. I know there are many others but their titles elude me at the moment. I suppose "Alex and Me" would be a great place to start looking at animal behavior and emotion since it is the unspoken other side of the coin of scientific research on animal behavior.