Not necessarily. Sentient is closer to self-aware. They try to improve their living conditions not to survive, but for sheer comfort. Chickens don't do that. Most animals don't; only higher level primates and...whale-type animals do I think...
Whether farm animals are sentient or not is up for some debate, because it also requires some form of consciousness, which is a really nebulous quality to test for. What they are not is sapient, self aware or able to process the thought "I think, therefore I am" which is generally considered to be what separates us from the rest of the animal kingdom.
This whole argument will be moot when we breed animals who want to be our food.
This whole argument will be moot when we breed animals who want to be our food.