I'm gonna look at your formula for the way I look at it. After its said with purebred you may have that market that works for you, I think poorfarmer is probably a commercial guy, and thats who my market is.
Phenotype Im good with.
Milk is what grows these calves, I don't want extreme but 20 to 25 I'm good with, but low to no milk not for me.
A few thoughts, growth is 80% genetics, 20% milk. The higher milking cattle will have higher year round maintenance requirements, ,which in turn, reduces stocking rate. Stocking rate is the most important factor in profitability.
$EN. Is not something I even look at, it will go to stocking rates.
BW zero or below. Never on a cow around here unless her BW is way high, if a mature cow can't handle some BW she has no place here, and if you stay in the negatives Thats what you get cows that can't handle it.
Our heifer calves average 63#-70#, bull calves average 65#-72#. This seems to me to be the balance between a healthy vigorous calf, and no problems. Keep in mind the cows here are 1050# to 1200#. We calve on several farms, some have no facilities, we cannot lose calves or cows. Our calving issues average about 1%, that includes retaining the heifer crop each year
WW and YW plays a big part to the commercial guy that would buy your bulls, they sell lbs. If your feeding them out right on your place no worries.
We are on track for a hayless winter for the cows. We do sell pounds, which are about 20% higher with 120 more, moderate/efficient/lower milking cows, than a hundred high performance, larger, cows, on the same ground
Now stocking rates and $EN. UT says cows eat X lbs per day per hundred weight. Now using X lets say you can run 12, 1000lb cows or pick 10, 1200 lb cows( just assuming here your cows are smaller) I'm gonna run 1400lb cows which will give me 8.5 cows on the same amount of ground. Now if performance is the same and they wean calves at 50% of there body weight. You have 6000lbs of calf I have 5950lbs of calf, your 10 or 12 got me by 50lbs, but now lets vaccinate the calves. 8.5 will cost me $127.50 your 12 will be $180.00 saving me $52.50. Now cows mine $144 yours $156 Thats taking weight off for worming still saving me $12. I've saved $64.50 making it about break even on the 50lbs of calf I lost. And with all that Im saying stocking rate means nothing to me as long as she performs.
I do not agree with your numbers. Two 1200# cows will not produce the same, or be as efficient, there are genetic/maintenance differences, back to the milk subject, which drives year round maintenance requirements
Now a question, you say easy finishing. How long and at what weight do they finish?
The first requirement of a cow is survival, the lower maintenance, the easier. Second is fleshing ability, which is required for high fertility. Last is getting bred back. The easier the first two, the more calves. Easy fleshing, moderate cattle, are more fertile, have more calves, with less problems.
All this is just looking at it from the other side of where your at.
