Sentience may not necessarily mean moral relevance.
For example to be a member of a moral community, which are groups of people who agree to uphold and undertake certain actions with a shared belief of what is good or bad, requires more than just sentience.
For me personally the ability to hold someone accountable for their actions in some way is an important component of moral community membership.
Animals are not held accountable in the same fashion as humans and so it could be argued they don’t deserve membership in our moral community.
If that’s the case then they have some kind of diminished moral standing.
You may then argue that a fetus or comatose person also has diminished moral standing so what obligation do we have in those instances?
One answer to that would be to hold the belief that although a fetus or comatose person is unable to have complete membership to a moral community they are impeded by other circumstances and if those impediments were removed they would be full members. A cow on the other hand will always retain the cognition of a cow, excluding it from full membership.