Two recent calves away from here :
1) Luther (1/4 Jersey 1/4 Red Devon 1/2 Angus.) Castrated at one week. Not weaned, grass and milk only. Sent away at 10 months old, unweaned, 244kgs deadweight
2) Odin (1/2 Jersey 1/2 Angus.) Uncastrated. Mother died at 1 month old, hand-reared on cows' milk (not from here but fresh from the cows) from thereon. Weaned at 3 months. A bit of grass pellets once a day, otherwise just grass (decent pasture) from thereon. Sent away at 7 months old, 122 kgs deadweight.
Odin was the half-brother of Flare, the mother of the first. (Flare was Hillie Jersey x Red Devon.)
Not directly comparable, of course, but some of the difference was age, some breeding and some the difference in reared on mum vs hand-reared.
This year we have Northern Dairy Shorthorn cross calves, one born here and one bought in (one calf born dead so we bought a replacement from the herd we got the in-calf heifers from.) So far I am well impressed. Much hardier than Jerseys, much better shape (more meat at the back end), and they are growing on well. The one born here is 1/4 Jersey (mum is 1/2 Jersey 1/2 NDS) and the bought-in is Friesian x NDS. The same cow is feeding both, with both getting a bit of a top-up from the other cow (who is 1/4 Jersey.)