If you were to chart "maternal" at its simplest form it starts at those little short faced, short necked, wide eyed, dished forehead females on the far left that spend all their inputs on getting bred and having calves. There is very little energy wasted on growth as it is antagonistic to maternal success. As you move to the right you get into better cattle from a growth perspective that still possess the ability to breed back and you'll notice they maintain a wide muzzle, wider eye set, maybe a dished forehead, natural ear set, and normal snout length. As you move to the far right you'll see many of today's modern growth and carcass type animals with their long ant eater snouts, a protruding forehead, narrow nose, and high ear set. There are people who will claim this is all a direct result of hormone levels that affect fertility. They'll even make statements claiming these levels affect where a calf's whirl is located on it's face. I don't know about going that far, but there are obvious trends that align with our understanding of maternal and terminal traits and just how antagonistic they can be to one another. Place the $B of various animals on the same chart to form a line and tell me what you notice about their skulls. I don't think it's a coincidence. This heifer's face is obviously too far out of the norm for me with her narrow nose, long snout, high ears, and slightly narrow eye set.

Basic wedge theory has males and females being opposite of each other when everything is optimal. Proper selection of secondary sex characteristics leads to bulls with front ends being heavier than their rears when viewed both from the side profile as well as from an overhead view. Those bulls tend to produce more fertile females of the opposite wedge shape with deeper wider rears as compared to their more feminine front ends. You often hear people talk about how correlated pelvic scores are to frame size, which leans to selecting more terminal animals, and how you have to be careful culling based on it. I'd challenge those people to start putting more emphasis on the numbers that go into the final pelvic score and to quit overlooking how wedge theory when viewed from the top affects one of them. This heifer has nice base width in her chest, but her shoulders are as wide as her gut, and her gut is significantly wider than her ass. This is exactly the opposite of what nature continues to show us to be optimal from a maternal standpoint. 

I walked a set of cows in Canada close to 20 years ago. The old guy pointed to some cow slowly grazing that he was very proud of. "That's the 622 female out of the cow we brought up from your neighbor. She's really nice, just look at her slowly mowing down grass with that big old muzzle. Now look over there, thats 107 from those Australian genetics XZY imported. It takes her three bites just to get one of 622's. She's working three times as hard and didn't even breed back last year." I was kind of young at the time and got a kick out of this because the guy had more money than god and owned numerous cows known nation wide and yet he was talking about their noses. It stuck with me so much I still remember it and the particular cows and have often wondered how it might apply to the amount of fescue cows are required to consume down here and if taking one wide slow bite really makes that much difference than 3 fast little ones. 

Another example that has always stuck with me is a particular bull I saw at stud years ago. He was hot on the scene and had a big time owner, so he kind of blew up fast. He quickly cooled off because his bws were a little too high, the calves had some extra smoke in them, and new bulls came along. I happened to be walking through one of the studs when he was there during the time all the rumors about how bad his attitude was and how big his shoulders were. All I can tell you is I laid my knuckles on his nose with my thumb and pinky spread as wide as possible and couldn't believe how wide it was. As I yelled down the alley to have my dad come look at him I couldn't help but think about that old guy in Canada as I was looking at a high 6 figure bull and talking about his nose. But, that's the tip of the wedge and he also expressed the correct shape all the way back. He wasn't my breed, so I didn't care what people were thinking or doing within his breed, but I couldn't help but notice his females went on to dominate for years to come and his semen is a hell of a lot more expensive today than it was when everyone was trying their best to run him down. His bws are still too high and the occasional calf has some smoke, but they are the maternal base you'd expect from a properly built bull and will do their best to raise their calves.

At some point it seems like people have forgot about the basic rules of nature in our chase for the cow that can do it all. I'm not even sure academia teaches these things anymore, but I guess there's probably not any money to be made in telling people to keep it simple.