We broke a 17 month old heifer last fall. She's as high headed as any Hereford you'll find. We pulled her off the pasture with one other heifer for company in a pen about 20x20. We hand fed them for several weeks and stood around as they ate. We gradually started using a scotch comb on them as they ate and soon they wanted scratched more than the feed. We also carried the rope halter with us after they were looking forward to us visiting. We were able to slip the halter on the calmer heifer with no problem. The high headed one we ran into the chute, put the halter on, and brushed her until she stopped fussing about the halter. Then I tied the halter on the outside of the chute and opened the chute. She hit the end of the rope and just fought it a bit. I left and came back an hour later to find she had gotten the halter untied and was loose in the small pen. I walked up, took the end of the rope, and slowly walked her around. She was still spooky, but she knew she could trust us. We worked with her several more weeks, then turned her loose.
Last week she calved and lost the calf due to a malpresentation. We slipped a halter on her and led her to another pen and grafted an extra twin on her. Several people who saw her last year when we first penned her said we'd never get her broke. It wasn't her fault she lost her calf this year and because she can earn her keep by raising a spare twin she'll get another chance.
So, yes, breaking yearlings is possible, just take your time with them.