Tim,

As I am very much a beginner, I find the best way to understand Hereford EPD's (I don't know anything about other breed EPDs) is by looking at the bar graphs.

A bar to the right of center means "better" than the breed average for registered calves born in a certain year. Plus is usually "better" except in the case of backfat thickness where a minus is to the right. That one is debateable whether morew or less is better.

For example, here is the AHA EPD bar graph page for this last heifer to calve over the Easter weekend (43022834). She is the one with the +2.8 Calving Ease Direct EPD. I see in the spring recalculation she is now a +2.4

Here is the AHA EPD bar chart for my other heifer with the +5.9 CED EPD (42987361). I see in spring 2011 she actually went up to a +6.0.

In both cases the EPD seems to have been a good predictor of reality. Of course we still need to provide good mineral, keep them in condition, use a good CED bull, and in my case keep pregnant females off of grazing corn, etc.

But all else being equal, these two calved unassisted on their own while my other, more impressive looking heifer but with a CED of 0.2 did not. The 0.2 heifer's sire actually has a CED of MINUS (-)1.2, both of which numbers I should have paid more attention to.

BTW, as it says on the bottom of the graph pages the Hereford breed average CED EPD for 2008 born calves is 0.1. 

All that means is the heifers with CED's of 5.9 and 2.8 are much more likely to be able to calve unassisted than a 0.2 heifer. 0.1 is "average". So the 2.8 and 5.9 are much more likely than the Hereford average to be able to calve unassisted. I am not saying Herefords are any better or worse than any other breed. What I want and need in my particular cattle raising system is a herd of females and bulls with "above average" CED EPD's.

These numbers are recalculated twice a year and will change slightly as sibling information is registered. I am comparing the spring 2010 numbers.

I am not knocking folks who check on their cattle every two hours during calving season.  I just can not do that. It also seems like if you retain heifers out of a "every 2 hour" system that eventually you end up with a herd where heifers require "every 2 hours" attention.  It is my hope that if I retain only females that can calve unassisted that eventually I will end up with a herd where "unassisted" is more the norm, even for heifers. 

Granted there may be calving problems even with the best calving herd but I want that to be an absolute minimum and a rarity. It appears that paying more attention to EPDs from trustworthy breeders will help me in that direction.

There is more on the AHA website explaining Hereford Calving Ease EPD here.

Note the quote from the above:

the most accurate selection for calving ease occurs when producers use calving ease EPDs but ignore birth weight EPDs.

Jim at Dawn