Angus epd question

[mncowboy]

How are Milk epd's determined? If an ET bull's sire (2006 model) has a milk epd of +21, and his dam (2011 model) has an epd of +18, and his shown in the catalog as having a milk +20. Why is it after I submit a sample to Angus GS, his milk EPD comes back as +12?

Is +12 likely going to be it? Thats lower than both his parents?
Just getting his first calves now and I'm concerned his daughters wont milk enough based on the Angus GS after thinking the+20 listed in the catalog was appropriate.
Thanks in advance

 

[Ebenezer]

MM is not all milk. It contains the catchall of stronger maternal aid to calves to do better and whatever else that is not picked up with other production EPDs. I do not know how long it takes for an animals to become obsolete based on numbers but numbers for older animals do not equal the numbers for current animals. You can use a 1965 birthed bull with negatives and get great calves. I think that the AAA needs to fix the system if they want to represent the whole breed (but they do not!). And I still think that the animals which are most accurate with the DNA testing are the ones closest kin to the majority of animals in the genetic data base.

"Maternal Milk EPD (Milk), is a predictor of a sire's genetic merit for milk and mothering ability as expressed in his daughters compared to daughters of other sires. In other words, it is that part of a calf's weaning weight attributed to milk and mothering ability."

 

[simme]

The milk epd is complicated. Some epd's (bw, ww, yw) are based on easily measured traits (pounds of weight) from the animal and their progeny. Expectation is that more pounds measured will result in higher epd's for the trait.
Milk is not directly measured. I have simmental. Their units of milk epd is pounds. Pounds of weaning weight due to the mother's milk. Genetic growth ability will affect weaning weight. Mother's milk (quantity and quality) will also affect the calf's weaning weight. This implies that the weaning weights submitted on progeny will affect the ww epd of the bull as well as the milk epd of the bull. In the case of milk, it would have to be the weaning weight data of calves from daughters of the bull. The question I have always had is how does the epd model split the contribution between growth due to genetics (ww epd) and growth due to mother's milk (milk epd). If a calf weans off good, is it due to growth ability or mother's milk ability? Well, both, but how much to attribute to each? I don't know the answer.

I remember a 2 y/o heifer than weaned a heavy bull calf. The calf's milk epd came back significantly less than the average of the sire and dam's milk epd. My thinking was that the dam must have been a good milker to wean a heavy weight calf. Response from the association was that growth and milk are antagonistic. That high growth animals tend to have lower milk ability. Since the calf's growth was more than expected, the milk epd was reduced. I was and still am confused on that.
Simmental association registers crossbred (percentage) animals and calculates epds for them. So, heterosis comes into play in the calculations. A Sim-angus cross should have increased weaning weight due to heterosis. So, a small portion of the actual weaning weight on the calf is discounted since it came from the heterosis, not the genetic potential of the sire or dam. Complex and confusing.

Enhanced epds from the genomics is supposed to increase the accuracy of the epd's equal to the increase of around 25 progeny. Based on my limited understanding, I tend to think that the new epd might be more correct than the sire/dam average.
It seems to me that epd's on young animals are much more likely to go down than up as they get older and epd's get more accurate. Just seems like half would go up and half would go down if the science were correct and accurate. Complex and confusing.