EPD question

[Lisagrantb]

How can 5 different bulls have different stats on their EPD's especially birth weight when they have the same sire and dam and all born within 2 weeks of each other.

 

[Silver]

How can 5 different bulls have different stats on their EPD's especially birth weight when they have the same sire and dam and all born within 2 weeks of each other.

Are they all born in the same locale? Seems to me that has something to do with it but I'm epd illiterate on purpose

 

[Lisagrantb]

Yes same farm

 

[Josher]

The old gene pool is a complicated one. If u compare to people. U can have same parents and their can be some similarities in offspring and there can be some very extreme differences. Someone else will have a more scientific explanation .

 

[Lee VanRoss]

Siblings can run up to 15% difference in dna traits. Yes it divides each generation. If there is a match between two carrying a dormant
dna the resulting progeny difference can be profound.

 

[Silver]

B

Siblings can run up to 15% difference in dna traits. Yes it divides each generation. If there is a match between two carrying a dormant
dna the resulting progeny difference can be profound.

But that does not explain why each calf would be assigned a different "Expected Progeny Difference."

 

[gizmom]

How can 5 different bulls have different stats on their EPD's especially birth weight when they have the same sire and dam and all born within 2 weeks of each other.

How can a brothers be so very different in looks and temperament. Just because they have the same sir/dam or Mom/dad won't make them the same. When the fetus is forming it picks up little bits and pieces of the sire and the dams genes its flush brother also pick up pieces but may grab some that went back to great granddad hoss who was 7 ft tall and weighed 200 pounds while the flush brother got his genes from great grandma Hattie who was barely 4ft tall and didn't weigh 90 pounds. So even in flush mates you can see differences, it all boils down to how the DNA lines up. We had a group of 7 flush Brothers had them genomically tested 6 of the 7 were low birthweigh bulls ranging from .3 to 2.1 with ced's of 6 or better but the 7th calf had a 4.2 birth weight and a -1 ced. So no 7 had to have grabbed his DNA from Hoss.

 

[Silver]

Maybe I misunderstood the initial question. I did not see where the calves had different birth weights. Everyone knows genes can express themselves differently and not every full sibling will be the same. The question was why would they have different epd's? In my mind they would all have the same odds of expressing any given trait.
But as I said above I don't know much about epd's. Aren't the initial epd numbers for a calf determined by using formulae using only the epd's of the dam and sire?

 

[simme]

I assume these are all embryo calves born from recipient dams. Is that correct? If the EPD's are enhanced due to genomic testing, you should expect the genetic makeup (and EPD's) to vary as gizmom described. If there is no genomic testing, then EPD's could vary due to actual birthweights being measured and submitted. However, that would not be true for embryo calves as BW is partially determined by the recipient dam and therefore actual BW's are not used in the EPD calculations. I am left with the guess that genomic testing was done and changed the EPD's since I can't think of any other possibility. So, were samples submitted for enhanced EPD's?
Purpose of genomic testing is to increase accuracy of the EPD's due to a detailed look at the actual genetic random combinations that occurred as the chromosomes from the egg and sperm uniquely merged at conception. Without the genomic testing, the EPD's would be calculated as equal based on average of the sire and dam EPD's and then adjusted for each animal based on their actual measured performance. For instance, the WW EPD would vary based on the fact that all 5 did not wean at the exact same weight. If 3 were assisted at birth or heavier at birth, their CE and BW EPD's would be adjusted to reflect different valves based on measured or observed actual differences. EXCEPT if they were raised by recipient dams since the recip would be responsible for a portion of the measured difference.
Keep in mind that EPD's are EXPECTED or predicted differences. Not guaranteed. And not very accurate until data on lots of progeny is collected to improve the accuracy. Genomic testing gives you a headstart on that improvement in accuracy.
What breed are these? I believe there are differences in the calculation models used by different associations. Your breed association can perhaps offer a better explanation if you contact them.

 

[wbvs58]

Simme has just stated what I was going to say but explained it a lot better than I would have.

Ken

 

[Lee VanRoss]

Silver If a 15% factor applies to dna then it seems logical(to me a least) that it applh to GED. I have never seen good results come from attempting
to make wholesale changes(improvemnts if you will) with EPD's. Weaning weights is the biggest one in the last 20 years, Like begets like so the result
has been larger harder to keep brood cows.. Cows amd corn have one thing in commo. Profit comes from bushels per acre not the size of the stalk
and pounds of beef per acre not pounds of beef pet cow,. Mh viwpoint

 

[Lisagrantb]

They are Angus and 15 months old. I'm sure they genomic tested but I will verify this. The genomic testing part is what was missing from my understanding of EPD's. I appreciate the help from everyone, and that's the one new thing I learned today. Thanks again.

 

[FungusProudKY31]

"the EPD's are enhanced due to genomic testing" and how linked they are to the base genetics that set the parameters in the genomic testing will affect the correctness of the adjustments. Correctness versus accuracy is not a play on words.

 

[Lee VanRoss]

If there is anything I have learned while on this forum it is I am blind as a bat without my glasses! Your patience is duly appreciated! LVR

 

[Silver]

Now that it has been explained that there was genomic testing and that they are not newborn calves from embryo transplants it all makes sense.

 

[simme]

Keep in mind that the calculation of EPD's is very complex. The explanation that I offered above is a very simplistic rough view because that is about as far as my understanding goes when you get into the deep details. Mathematical/statistical models are very complex. With EPD's, there are some traits that are inter-related to other traits. The models must take the physical measured and observed data and correctly/best assign it to an EPD trait. For instance, weaning weight is easily measured. But what portion is due to the milk quantity and milk quality of the dam and what portion is due to the growth ability of the animal? How much growth came from the dam and how much from the sire? The complex mathematical models attempt to resolve all that. The weaning weights on your five bulls all being inputs to the model resulting in updated EPD's not only to your 5 bulls, but to all the contributing animals in their pedigree back for generations. I expect that for these complex relationships the models have to be run thousands of times until the numbers all finally converge. Each run using intermediate results from the previous run until the final numbers remain the same. When EPD's were developed many years ago, the computing ability and cost dictated that the EPD's were only updated once or twice a year - due to effort and cost. I think now they can be updated daily.

Some people don't put any value in EPD's and some perhaps put too much faith in them. But, I believe they should be one of the tools used. Most any cow/calf person with at least a few cows can name/identify their best or better cows. They know which cows wean the heavier calves year after year. Which cows have higher BW calves and which cows have lower birth weight calves. Which milk better than the others. All based on observation and measurement. If you sell your calves at the auction barn, you can read the weights on the statement. That in a simple nutshell is the principle behind EPD's. Predicting the performance of an animal based on observed and measured traits. Better when based on an unbiased set of complex equations looking at data on thousands of animals. Not perfect, but a very good tool. My thoughts on selection. Make initial selections based on what you see. Then finetune those selections based on the EPD's (remove the culls from your selections). Probably can do it in the reverse order just as well as long as you do both. Always consider the EPD accuracy as well as the number. Knowledge of the cow family is always important as well.

Some people believe that the breed association manipulates the numbers to someone's advantage. I don't subscribe to the conspiracy theory. They are trying to make the models better and better. I think most of the "manipulation" is unintentional and comes from the breeders when they don't submit data on all their animals. There have also been attempts to manipulate EPD's by submitting false data on a bull's calves which have limited use among a few people. There will always be those who try to cheat the system.

I got wordy again, didn't I?

 

[gizmom]

How can a brothers be so very different in looks and temperament. Just because they have the same sir/dam or Mom/dad won't make them the same. When the fetus is forming it picks up little bits and pieces of the sire and the dams genes its flush brother also pick up pieces but may grab some that went back to great granddad hoss who was 7 ft tall and weighed 200 pounds while the flush brother got his genes from great grandma Hattie who was barely 4ft tall and didn't weigh 90 pounds. So even in flush mates you can see differences, it all boils down to how the DNA lines up. We had a group of 7 flush Brothers had them genomically tested 6 of the 7 were low birthweigh bulls ranging from .3 to 2.1 with ced's of 6 or better but the 7th calf had a 4.2 birth weight and a -1 ced. So no 7 had to have grabbed his DNA from Hoss.

Sorry Silver I don't think I really read and understood the question as well as I should have. In my mind I assumed the differences were due to genomic testing.... I assumed and after going back and rereading realized genomic testing had not been mentioned my bad.