I'm a beginner as well, so I'll try to answer some of your questions based off of what I've been learning myself!
(welcome)
So, I'm not sure about the percentage of protein... I'd actually like to know that as well... If its anything like swine, lambs, goats, and other livestock, I assume you'll want to start with a higher percentage of protein and lower energy, then gradually decrease the protein as the steer grows, increasing the energy. Protein is for growing bone, structure, muscle, etc. so they need more of it when they're young, but as they grow, their needs change and they then need more energy to fill in their frame. Please correct me if I'm wrong though.
For beet pulp, I'm pretty sure that its mostly used as a show day fill product. On show day, you feed it to them (wet or dry, I'm of the belief that if you feed it to them dry it will expand more once it is in the gut giving more fill) then try to get them to drink as much water as possible which expands the gut/rumen giving them the appearance of a deeper body, more spring of rib, and more overall fill. I think I've read that you can start them on it prior to show day to kind of stretch out the gut ahead of time, but I'm not as familiar with that process.
Not as knowledgable about the hay... everyone where I am feeds oat hay. I know they need the roughage to keep the rumen functioning properly, but I'd love to hear other's opinions on the best hay.
As for exercise, its my understanding that you cant really put muscle on them through exercise like you can with lambs and goats. However, walking them is important as it breaks/trains/tames them for the show ring, and it keeps them sound. So for muscle, you're going to need to rely on genetic potential for how much they can build, nutrition and supplements for building it, and exercise for toning it and keeping them sound.
I've heard a lot of different opinions on calf manna, but I don't think I know enough to comment on it. Try putting a search in, a lot of helpful results will come up.
Tying them up seems to be another controversial topic. I'm of the opinion that tying them up is important. It trains them to keep their head up and more importantly, allows them to build the proper muscling up to help them keep their head up. You aren't going to get a great head and neck though if they don't have the genetic potential for it. It'll just help when you're showing him. I hope someone else chimes in with more info on tying them up though. I know you're supposed to gradually increase the amount of time they're tied. Its also been suggested that since at the fair, they're going to be tied up practically 24/7, you get them used to that in the couple of weeks before fair.
Supplements... this is a harder one to answer... it really depends on the steer. Study him and decide what he's lacking in. For example, if he's lacking depth, look into fill and depth products like beet pulp and depth charge. You will want to invest in a quality mineral if your feed isn't already providing one. I've read on here a lot that the vitaferm products are really good because they contain anaferm. Again, a search will help with this. Find out what you'd like to improve on your steer, then put a search in on here, and you should have a good place to start. I don't know if you're show is a slick or hair show, what your steers genetics are, or if you need help with growing hair, but if you do, look into Tasco/Kelp Meal. Also, put a search in on Stabalized Rice Bran... you wont be disappointed!
Hope this helped a little, and I hope some of the more experienced people will chime in.
Good luck!
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