Inbreeding Depression Quantified

So as I venture along, I'm becoming more and more dismayed with efforts to sell purebred cattle. I sold a cow last Fall for maybe $1500-- a 3 year old, had her baby second calf at side. She did just an ok job with her first calf-- just over a 600 lb adjusted 205 day wt. Raising her first calf last winter was hard on her, but she did it, and bred back to calf on time, and was in decent condition when she calved, and when I sold her a month later. Fast forward to this week, almost 4 months post-sale. The man calls. He doesn't like the cow. He doesn't like the calf-- apparently, they are his worst cattle and he wants me to do something-- he actually wants to look through my cows and pick out a trade-in. Well, we really aren't going to do that. He wants me to look at them, so I'm going to do that. If I want them back (I actually thought more of the heifer than what he paid for her), I'm going to give him back his money. If I don't want them, I'm going to have him sell the pair and I'll give him the difference-- I can't imagine it'll be more than a couple hundred bucks. So I'm going to "fix" his disappointment despite not really being all that clear why I should. But I will, and look cheerful doing it.

Here's the question: Both calves-- the first one and the second one-- were sired by my bull. My bull and the young cow are paternal sibs by a bull (who is about 6.5% inbred himself) and there is some additional inbreeding in the pedigree. The IBC of both calves is 14.3%. Does anyone know what the expected pounds performance depression is for specific levels of inbreeding? In other words, would one "expect" an X% decrease in weaning weight for X% IBC? I'm sure this has been done, over and over again, but can't find anything.

Here is a graph of opens and death loss:

http://pods.dasnr.okstate.edu/docushare/dsweb/Get/Document-1974/F-3165web.pdf

Welcome to registered selling MS and one reason why I want no future part of it...dealing with people clueless about cattle who are disappointed from too great expectations, and run down your failures...then you also have the con game crowd who buy your stock and aggrandize them beyond what is reality, creating false expectations for the next foolish buyer.... a lose/lose situation...
is the cow/heifer calf now located closer to you or me? still $1500? no papers needed; open and ready to breed to the bull of my choice?
ibc/regression effect equation...multiply the ww by 1/2 the ibc, and add on...very inaccurate though, because like epds, the ibc is
an average of what happens..source...Mike Keeney

Thanks Mike, Kent. With Mike's formula, for a 600 lb calf, 15% inbred, -- 45 lbs is the inbreeding deficit. From Kent's table-- if growth is like open, it is about 5% decreased at 15% IBC-- so the deficit on a 600 lb calf would be about 30 lbs. Close enough for me-- the inbreeding might explain 30-45 lbs. of deficit.

The pair is in SW Virginia, a good bit closer to me than you Mike. Probably not worth worrying too much about.

MS, I do not want to derail your topic, but some 2 year old put together at the sale barn, bred to common bulls, some with month old calves brought $1700 a round, down to 1300 here, this week. No pedrigree, no background, no guarantees. If she was mine, I would probably just pick her back up, and not sell the fellar' anything again.