That's something I can't answer with any certainty. After several generations it may not be noticeable, but color patterns are sometimes unpredictable and can show up on occasion down the road. We have a Hereford x Shorthorn cow, that had an Angus calf, she is mostly black but does have some white on her back and belly as well as some evidence of having roan markings on her head. Both the cow and heifer had calves by a Hereford bull this time and their calves are nearly identical showing no roan or excess white looking more like red baldies. If I were guessing I would say that after several generations that most calves would not be showing it but would also not be surprised if a few odd marked calves still occurred. It's something that if you have a market for cattle outside of taking to the stockyards then it doesn't matter near as much. We sometimes sell some straight bred Hereford heifers out privately. They are docked at the market, yet some people seek them out specifically. We also most often choose Herefords or red Hereford crosses for feeding out as beef calves, instead of black ones because the black calves do better at the market. We are limited though in what we can sell outside of the traditional stockyards setting, so when we sell there it's always nice to take a group of black calves. It's unfortunate but the dock results in a substantial amount of money left on the table when selling red calves and it costs the same to raise them.