The ranch should be divided into production enterprises. For example, yearling replacement heifers, stockers, cows and calves, and individual crops should be considered separate enterprises. I have a strong personal preference for having inventory-based livestock records. I think large ranches should record inventory changes monthly. This allows producers to look at several important factors such as percentage calf crop born, percentage calf crop branded or turned out, percentage calf crop weaned, and percentage cow death loss all based on beginning inventory.
Producers can also look at weaning weight per calf and per cow.
When pregnancy checking, simply calculate the percent pregnant of those checked. You will then be able to combine production data with cost data and determine cost per cow, per calf and per pound of calf weaned. When combined with marketing data, this approach allows you to see the big picture first. These kinds of records give you a format for budgeting, analyzing and planning the future. Today's low cost computers have made it very easy to keep these kinds of records.