Don’t all sheep cost the same to keep? I’m guessing there may be extra cost with ewes associated with lambing issues? But what about rams? They all eat grass. I don’t think one extra mouth would cost much more in any winter feed that might be needed. And he’d still need vaccs, wormer, fluke, fly strike treatment.
No, they don’t all cost the same. A breeding ewe is the most expensive. She is growing lambs, then making milk for them, then getting fit again for tupping again, alongside keeping herself fit and growing her fleece. It’s a lot more work than a tup does, who is basically a dosser for 49 weeks of the year then works his ba11s off for three weeks

. And a wether does the least, all he has to do is keep himself going and grow a fleece.
Each will eat what they need, and that’s a heck of a lot more for a ewe than a wether.
You pretty much never need to give supplemental feed to a wether. In winter, the wether needs less than half the hay a pregnant ewe does, and in the 6-8 weeks before lambing and a few weeks after, the ewe needs cake too. In spring and summer, when she’s making milk for her lambs, the ewe will eat at least three times the grass a wether will, or grass and cake if the grass hasn’t come in yet.
You can get the info and do the maths if you want. There are lots of figures published for dairy cattle, talking about maintenance ration - what she needs for her own body, and what she needs on top of that to make milk and then to grow her next calf. A wether needs only the maintenance ration.
Because a ewe is always working very hard, her body is more stressed, so she will need meds way more often than a wether, and will also need more minerals and supplements for the same reason. In a twelve month period you would probably vaccinate a ewe, worm her once or twice, give her mineral supplementation once or twice, maybe copper needles once, blue spray for her feet once or twice. Once every three-five years on average maybe she needs antibiotics, anti-inflammatories, or other treatments. Mr Pie my senior wether always has access to a lump of Himalayan rock salt, as do all our livestock, but I can’t remember when I last had to do anything with him apart from shear him. Oh, yes, I had to pull a thorn out of his foot shortly after we arrived here, three years ago, when they went into grazing where the blackthorn hedgerow had been recently trimmed.
Adult sheep under no stress and not wormy really shouldn’t be needing flystrike treatment.
I guess one thing that all sheep would need is if you are in a fluke area, you would probably fluke any wethers as well as the tups and ewes.