Oh My......My beef production class was soooo long ago. If I recall correctly, the cow probably has more impact on calf vigor than what the bull does. However, the one factor (maybe 2 factors, but related if not the same) that I can remember that the bull is a major contributor to and has an impact on calf vigor is calving ease and birth weight/size (again, colsely associated if not the same factor). For many years it was desireable to keep increasing birth weight, and then there was a dramatic increase in dystocia. I do recall an instance where a producer told me he got a bull that was to throw absolutely huge calves. He thought this was great. However, he was concerned about breeding him to his first calf heifers. To be on the safe side, he only bred the bull to his 5 largest cows (each over 1,500 lbs, IDK where he got cows that big). The end result: all 5 cows had dystocia complications. He lost 4 of the cows and either 4 or all 5 of the calves. ......He got rid of the bull. My thought would be to take all the epd scores and look at them in combination. You may put more value on one particular score as a personal preference, but don't totally disregard the other values.
Condition of the cow is going to play a big, non-genetic based role in birth vigor.
