You should be able to feed less of the higher protein cube with the same result. Not sure my math is correct doing it off the top of my head here. For example 2 lbs/day of 16% cube should be about the same protein level in the overall ration as 1.6 lbs of the 20% cube. Plug in the cost per ton for each cube to figure what would the total cost be to feed X number of heifers at Y lbs per day.
Another thing I'm not sure of is that all protein is created equal. I'd probably stick with an all natural lower protein product if the higher protein involved urea or feather meal but that's just me :idea:
TB can probably give you a more intelligent answer ;-) I'm going back to bed now :oops: