I just started using the Z tags, and frankly, I won't use anything else if they continue to work like they are now. I am seriously impressed with how good they stay in. It took us a few times to figure out how to insert them without a struggle, and the ear hole looks huge, but they are extremely easy once you get the hang of it. (The only thing I don't like is that they seem to hang up when you try to take the tool away though we have never torn an ear). But letting go of it and just pulling seems to work. Another thing I notice is that the calves don't cry upon insertion like they cry with the Y tags. I don't know why because the z tags look to make a bigger hole, but they never scream like they do on occasion with the Y tag. That makes our lives easier too since we don't want mama to act stupid. (We've had a couple let out a small noise, but nothing like the scream we get on some with the Y tags).
We decided this year that we would tag the calf with the mother's number/name, and the birth date of the calf. This has been incredibly easier and better for us. We not only know when the mother had the calf, but we also know who the calf belongs to. We tag the males in their right ear and the females in their left ear, so we know as soon as we see them which sex they are.
We like having the BD on the tag. If a calf is extremely young compared to another yet growing really good, we want to recognize the mother. This gives us a constantly reminder which of the calves we really like, and it reminds us that the mother is producing good calves as well as reminds us to look at the mother of the calf that is growing well to make sure she is keeping condition. (We mix our heifers and cows together since we don't have separate pastures). This helps us watch our feed closer.
But what it also does is keep the name of the cow in our minds so that we are reminded which cows we like and want to keep. It also causes us to not remember the names of the cows that didn't do a very good job.
Of course, we look at all our cows to see condition, but focusing on those that are producing the best calves helps us decide who goes.