It's an old veterinary joke - and a Swiss veterinarian once told me he'd heard it there, too - but, I once had a dairy client who milked Brown Swiss cattle call me - told me he had a bull calf that something wasn't right about. "What's wrong with him?", I asked...
"He knows how to suck!" he said. lol
Still want to try some Braunvieh sires over some of my Angus and ANxSH cows at some point - same gene pool, originally, but don't know if dumb calves are a problem. Local Beefmaster breeder had some Braunvieh bulls several years ago - loved the halfblood cows and the calves, but said the bulls were the meanest things he'd ever had - and they sometimes run a Jersey bull on heifers, so I suspect he knows mean... But, they recently got another group of Braunvieh bulls, so I guess he liked 'em enough to go back to the well.