Argument Against Davis

In Davis' article, The Least Harm Principal May Require That Humans Consume A Diet Containing Large Herbivores, Not a Vegan Diet, he discussed how 1.8 billion animals such as mice, wild turkeys, rabbits, etc., die each year for producing a vegan diet.
He makes a good/pessimistic point that no matter what you do, animals are going to die in the process of obtaining food. He uses this argument to disprove Regan's Least Harm Principal, yet, I think he's argument is a bit extreme.
When defending the debate of intended vs. unintentional death he states, "Perhaps I don't fully understand the nuances or moral significance of this difference, but it seems to me that the harm done to the animals is the same -- dead is dead."
This reminds me of what Nicole said a few weeks ago, 'We step on ants everyday just walking around and we don't even know it.' (Of course I'm paraphrasing because it was a while ago, but it was something to that general effect.) Animals and other living things are going to be killed by humans no matter what we do. Dead isn't just Dead, when it comes to moral significance. It is the action of killing on purpose -- for no purpose and even for unnecessary purpose that we need to morally consider. We cannot be morally accountable for the things we cannot control.
I really do not think that Davis understands this "nuance". A field mouse, before getting run over by a plow was not crammed in a cage like a chicken, it did not have its feet tied together like a calf, it did not have hormones injected into it's veins so that it would produce more milk or eggs. Is this not pain? Death from being accidentally run over by a mower is instantaneous therefore no pain is felt, whereas suffering from being controlled and physically manipulated over a life time is surly more painful.
In an other defense against Davis' stance is that people who are not vegans eat that food too. Non-vegetarians are not carnivores who chop on flesh all day. Bread, corn, soybeans, and the like are not singularly for vegetarians, omnivores like/need them too. So therefore the only foods that aren't eaten across vegetarians and omnivores are meat and/or animal byproducts. And as I mentioned before, the animals who are victims of animal forging experience more pain than animals who are accidentally killed by a plow because farm animals have experienced long-term suffering. So if we are trying to evoke the least harm principal, being a vegan would be the best route because omnivores cause more harm by consuming food that in its production killed animals and animals that experienced a life time of suffering/ their byproducts.

Question: Should we feel more morally accountable for the animals that die in the field than the farm animals we consume?