why is life no longer good in animal farrm

At the beginning of the story, the animals feel unequal to the humans that operate the farm. When the animals take over, at first they are all equal and they feel that life is good, but as the story progresses and the Pigs begin to sieze more power, the other animals quickly realize that their life is quickly becoming what it used to be when the humans were in control and that life is no longer good.