What you are saying obviously makes sense, larger frame size/heavier cattle should have larger frame size/heavier 205 day calves.  But they don't necessarily.

Another major difference is the growth RATE of calves. Note the difference in WW and YW EPD's among similar frame size cattle.

Sure the larger 1930 lb cow's calf will likely EVENTUALLY be larger than the 1360 lb cow's calf however it may take a lot longer for that 1930lb's calf to catchup and pass a quick growing, quicker maturing but smaller cow's calf.

And it may take the larger calf a lot more feed in addition to time to get to his larger mature size. Earlier the larger cow's calf may be more bone than beef at any given age compared to the smaller cow's calf.

In my particular case, the only thing that matters is calf size at about 14 months because that is when they are going to the processor...

Interesting to think about.

Here is a picture (yes, previously posted elsewhere but pertinent to this discussion) I took the other day from my shed of an 1875lb cow (on the left) nursing her 626 lb 183 day old calf right next to the 1360 lb cow (on the right) nursing her 770 lb 203 day old calf.  Even with the calf age difference, there is about a 100 lb heavier calf from a 500 lb lighter cow!

Growth RATES are evidently very different.

Jim at Dawn

(IMG_2118_41_66_nursing big calves_101010.jpg)

IMG_2118_41_66_nursing big calves_101010.jpg (71KB - 62 downloads)