The question of a right to life in animal ethics

In animal ethics a Right to Life has been postulated repeatedly, but no valid argument has been produced yet. Thus the question of a Right to Life in animal ethics remains unanswered. It is remarkable that no philosopher has yet found a valid argument against Epicurus ("there is nothing fearful in the absence of life"). On the other hand, there is - again based upon Epicurus' argument - a basic moral duty with respect to painless killing (i.e. no fear, no distress, no suffering).