Generally the flatter an animal’s back the better. From the side you want it high and straight (flat) and from the rear you want to see good development – not a ridge like a hog has. Bear in mind that this is the area where the best cuts of meat come from, hence the old saying “high on the hog” when describing quality.
Recommend you check out The Lasater Philosophy of Cattle Raising from you local library.
Look at a cow from the ground up. First she has to have good feet, you don't want broken down pasterns or grown-out hooves. Next is the udder, small well shaped teats placed uniformly. Udder attachment is also important, hard to judge unless the bag is full.
But read that book and if you can get it something by our about Jan Bosmara.
Both Bosmara and Lasater select based on the quality of the cow. Afterall about 95% of your herd is the cow.
I know Lasater's book is readily available and a good read. He wanted cattle that would basically take care of themselves and set out to create a breed that would do that.
Some other good resources are farm ag books from the fifties. They have conformation chapters as well as feed chapters . They also have good advice about farmstead layouts. I find them very interestin..
I don't know if this is quite what you're looking for, but the link posted below offers a very thorough overview of beef cattle conformation and carcass evaluating information, courtesy of the Land Down Under.
This link is in pdf format so may take a while to open if your internet is via a land line, however that being said, it is geared toward 4H and therefore beginning cattlepersons. Information contained is: finishing steers, conformation, feeding, digestive tract, carcass evalutation. Illustrated with drawings and clear photographs. Compiled by Marc R. Horney - PHD (University of California). A good educational site.
Something I think really helps is to go just sit and watch some shows. See what the judges are looking for and really listen when they explain their placings. That is how I am learning, except when there is a judge that is just stupid like the Harris County Fair last year. He said he didnt like the Beefmaster breed so all of those got dead last. All the Brahmans were first (small show, all breeds put together)
A good straight back is one of the things I look for when purchasing a bull. I still have breeding rights to my first bull, who has a great topline, and without fail has transmitted it to every one of his calves. I don't know how many cattlemen looked at him and that was the first thing about him they noticed. One even leased him for use on his commercial herd.
MPR was asking about cows not bulls. He can have the finest bull in the world but if he has sorry cows to put him on what has he gained.
Found this on the link Cattle Annie posted. It is a breed identification slide show mostly bulls. I have pulled out a couple that in my humble opinion are what a good fertile productive cow should look like. The one below is a shorthorn. I have read or been told that a cow should be in the shape of a triagle with the point starting at her head and getting larger from front to back.
After reading what you have said about a good top line, I wonder about a Bull that I just partnered with his rating is u2/1
, A balck beefmaster, most of my heifers are rated u1/3 or u1/2. I am trying to get a good grasp on what a good one looks like versus a not so good one.