From what I can glean from the rule as posted in the Federal Register:
1. Cattle under 18 months of age are exempt from the official ID requirement unless they are being moved across state lines for a show, exhibition, rodeo, or recreational event
2. Cattle over 18 months of age do not need to have an official ID as long as they are traveling within their state of origin.
3. Brands/tattoos/reg. #'s are still accepted as official ID ONLY if this is acceptable by the receiving state/tribe, otherwise you need a USDA metal tag or RFID
4. Not required if moving directly to an approved slaughter facility.
The only part I am unclear on is this: cattle over 18 months of age going to a market in a different state. They accept back tags for up to three days if they are moved from the point of origin to one facility and then to slaughter, but we all know that cows sent to a market as slaughter cows do not all end up losing their heads, so will these animals need official ID to go to a market if the market I use is in another state?