It is given value in ways human life is given value. Higher animals can feel love, pride, curiosity, and triumph. Some have a sense of humor. Usually they can show these emotions, too. Mammals nourish their offspring with love just like we do.
Many animals mourn their dead mates and family members, too.
These things give life value. Plants don't have these things. Most animals can also show that they hurt or suffer when their basic needs are denied. It is this suffering that is our best reason for valuing the quality of life for animals in our care. Again, plants cannot suffer, they have no nervous system nor consciousness to understand suffering.