Look, I'm not trying to start an argument, but let's figure it out.
The cow, land, property taxes, existing grass, water, management, vaccines, fences, etc. are all fixed costs aren't they? Meaning that none of the expenses change over time. These expenses all remain static.
Does the cow eat to make the milk the calf consumes? Sure. Is there an increase in the amount she eats? Of course. But the grass is there to eat and if the cow doesn't eat it then what happens to it? You can stockpile grass, and is there a benefit for later? Maybe if you need it. If it isn't needed, then what? Does it become a carbon sink as it molders into the soil? How do you quantify these things?
Maybe it could be argued that the calves going to the auction in a single trailer at one time might save enough on labor, fuel, and wear and tear on equipment that it actually saves money to take a hit on the price of a calf.
So how does that all play out in dollars and sense? (yeah, I meant to spell it sense) I've laid out the way I run the numbers. How do you see it? What have I missed?