I keep mine in a spiral notebook. Got a pocket organizer that hangs behind the seat of my truck that I keep it in. I do have copies that I keep at home just in case somethin were to happen to my spiral. I tried a computer program a few years ago, it wouldnt let me enter the kind of information I wanted to, was more trouble than it was worth, ditched it after workin with it for over a year. Just a waste of my time puttin info in and still not havin room for the important things I wanted on there. I usually end up with two sets of records a year since we work cows twice a year.
Example
birth year/cow# tag/date calf born/date bred/lastyearscalf
I keep it in columns. Very simple. I put a discription of the calf by the date it was born, heifer or bull. Then keep a record of last years calf kept or sold, tag numbers etc.
When my replacement heifers get the regular tag numbers I put them in the main list, along with their mama's tag number that way I know who they are out of. What bull was their sire, etc. It's not hard once you get it all written down in columns to keep up with it.
Then when we work cows I put the dates that all the vaccinations were given and what kind.
Bet that was clear as mud. lol hope it helped