Lazy ace,
Not a problem, hope some other people get something out of this.
Yep, this research was done in females and other than being different based on RFI, everything was similar between those that were efficient and those that weren't. The real issue is that we don't yet know what the long term selection effects for RFI are, although research at WVU has shown that RFI is negatively correlated with age at puberty in yearling heifers, meaning more efficient, negative RFI, heifers reached puberty when they were older as compared to less efficient heifers. At the same time though there were efficient heifers that reached puberty early and inefficient heifers that didn't even reach puberty at all. It really just comes down to managing heifers and challenging them reproductively in their first breeding season. Fertility is the most economically important trait and the best way to change it is genetically, not with feed or management.
Ideally, reduced RFI should be related to a decrease in maintenance requirements, since the calculation of RFI takes into account maintenance and gain. That was the problem with F:G. It only accounted for gain efficiency. Maintenance becomes pretty important for the cow/calf man's bottom line, since 65% of a mature cows feed requirements are for maintenance and that figure increases 30% with lactation. We spend more money to keep our cows alive than we ever do to actually get anything out of them. I'm not sure if this is figured into the Red Angus EPD, but RFI data is used in the new Angus RADG EPD, which is expressed a gain measure and not feed intake.
The bulls are developed in lots that are 40 feet x 120 feet and there will be 15-18 yearling bulls per lot.