What else do you want to use?
That said, in my opinion, as it relates to optimal ecosystems, sentience at best might be a consideration.
Impact, contribution, etc. to an ecosystem would be a more natural measure.
A wolf doesn't really care about the relative intelligence of the rabbits it kills, but has a natural kinship between other wolves or wolf-like creatures which more-or-less extends to, "I wont kill you for food unless I'm starving."
That aside, unclear how wolves relate to the topic.
Generally speaking, most life on Earth doesn't even eat other living organisms, but the naturally left remains of living organisms.
This is why using selective terms for the type of dietary intake is scientifically useful. Carnivores that eat other carnivores (on a preferential basis) are rare. Typically herbivores are eaten by omnivores or carnivores. The only real moralities involved in these distinctions relate to energy efficiency and likelihood of diseases being a concern. Of course self awareness (sentience) is an additional layer of consideration on top of the evolutionary pressures.
Learn more about detritus here:
Human society tends to operate on that logical fallacy. The badness/awfulness of others is taken to justify "extreme measures" from our own side. (And I would agree that this is wrong.)