Sure, that's true from a purely ecological perspective, but your argument does not capture the general inhumane practices that go on within the diary industry (

Sure, that's true from a purely ecological perspective, but your argument does not capture the general inhumane practices that go on within the diary industry (e.g., caging, keeping cows perpetually pregnant, separating mother / calve at birth, etc.). All of these combined create a life of significant distress for all the animals involved and should be captured as an "environmental cost" in your equation above.