EPD variation between flush siblings

[angus9259]

Flush siblings and CED ranges from -8 to +4. Safe to say not particularly "calving ease" - but how do you suppose the angus association decides the top animal is going to be a -8 and the bottom is a +4 (still quite a spread) and the middle... well.... somewhere in the middle. Check out the YW differences too. Where do these numbers come from? I kinda thought the initial numbers were an amalgamation of the parents but these three are QUITE different.

 

[simme]

Looks like they have genomic enhanced epds from dna. Is that correct? I don't know how AAA uses dna in regard to epd's. But the simmental association calculates epds at the time of registration using the parent's numbers and whatever data was submitted on the calf (bw, ww, etc). Then dna can be submitted for enhanced epds. When the dna data is received, epd's are updated to include the genomics. You can then compare the initial epd's to the new enhanced ones to see the amount of change. Sometimes it is considerable.

I think the result of genomic enhanced epd's is better accuracy, not necessarily better epds. Some epd's may go up and some may go down. If the epd's don't change after the dna work, then there would be no purpose in doing it. Look at the changes and differences as better information for selection, not as a mystery. I don't think it is unusual to see considerable variation in progeny of flushmates - with or without the genomic epds.

 

[Ebenezer]

"I don't think it is unusual to see considerable variation in progeny of flushmates - with or without the genomic epds."

You are dead on.

 

[angus9259]

"I don't think it is unusual to see considerable variation in progeny of flushmates - with or without the genomic epds."

You are dead on.

I get that. But how do they know? How do they KNOW one is going to be a -8 and one is going to be a +4? What makes them look at one pairing and say -8 and another exact same pairing and say +4?

I understand genomic "enhancement" - but that's just an enhancement of the number that's already been concocted. Where did the concoction take place? I feel like the association could just spin off any numbers out of one of those lottery ball machines and stick em in there. How would we know?

 

[simme]

I feel like the association could just spin off any numbers out of one of those lottery ball machines and stick em in there. How would we know?

I think that thought could be applied 60 years ago when EPD's/EBV's first started. I often wonder where the first set of numbers came from. But after all this time, there is a basis from a large set of data - both from generations in the pedigree and measurable individual performance. Genomics is a "measurement" or at least an analysis of the inherited genetics (dna) that is used in addition to the database. But remember that they are still Expected/Estimated/Predicted. With an assigned accuracy. Young animals without genomics have accuracies around 20%. With genomics around 40%. That is still pretty low accuracy and confidence in the numbers should be proportional to the accuracy. Phenotype, epd's, cow family, sire history - all important for selection. After all of those - ouija board or lottery machine may be used.

 

[kenny thomas]

As many of you know Simme is raising a bull for me. I think he was kinda disappointed with the EPD's until he done the testing. It changed considerably. Much better and that's what i expected from the bloodlines used.

 

[wbvs58]

They are 15 months old so some data would have been turned in already, BW, gestation length, weaning weight and possibly yearling weight, probably been scanned as well so all that data can modify the EPD's as well and when that data is combined with genomics they start to go their own ways. I have no idea what affect the recipient cow has on the figure as I have not been involved with any flushing of my cows.

Ken

 

[Ebenezer]

I get that. But how do they know? How do they KNOW one is going to be a -8 and one is going to be a +4? What makes them look at one pairing and say -8 and another exact same pairing and say +4?

I understand genomic "enhancement" - but that's just an enhancement of the number that's already been concocted. Where did the concoction take place? I feel like the association could just spin off any numbers out of one of those lottery ball machines and stick em in there. How would we know?

From what I understand on the genomic testing the # of genes (30k, 40K, 50K...) that are identified as test genes or markers are compared to the whole of the animals in a breed that have been tested. These markers can be the only or likely just a few of the genes which affect a trait. The testing reveals if an animal got the gene(s) or not. Then they run an algorithm to predict a particular EPD.

What I expect is that the genomic testing shows a tendency that an animal will be (your example) more towards -8 or more towards +4. Genomic testing is more long term for me with sheep but I did some yearling bulls this time to see which ones I'd rather put with heifers. Did I make the right choice? Next February will tell. But it is my best bet. So, accuracy is better but likely not perfect.