EPD's What Do They Mean?

[norriscathy]

Sorry to burst your bubble, but if something is 30% "accurate" the reverse is also true! It is also 70% "inaccurate".

That's why you have to evaluate the standard deviation and the associated possible change with any given accuracy. Statistics don't lie. EPDs are not an absolute, rather a selection TOOL based on statistical data. EPDs do work if you know how to interpret and use them.

At last! A sensible answer! Thank you! Do you know where we might find that information for any given breed?

 

[MikeC]

Still not convinced that EPDs are the best selection tool? Let's say you want to predict the yearling weight genetic merit of a bull and you have two pieces of information: an adjusted yearling weight and a yearling weight EPD. Assuming yearling weight has a heritability of 0.22, the accuracy of the adjusted yearling weight will be around 0.12. The EPD, on the other hand, would have an accuracy of around 0.24. That's twice the accuracy! This is possible, because the EPD accounts for information from all the relatives and any other traits that are related to yearling weight.

 

[Frankie]

Still not convinced that EPDs are the best selection tool? Let's say you want to predict the yearling weight genetic merit of a bull and you have two pieces of information: an adjusted yearling weight and a yearling weight EPD. Assuming yearling weight has a heritability of 0.22, the accuracy of the adjusted yearling weight will be around 0.12. The EPD, on the other hand, would have an accuracy of around 0.24. That's twice the accuracy! This is possible, because the EPD accounts for information from all the relatives and any other traits that are related to yearling weight.

Plus EPDs take environment and management out of the equation so that a bull that's creep fed won't have better EPDs than a bull that's not.

 

[Frankie]

Frankie & Jeanne; I am not questioning how EPD's are calculated, I'm sure the methods used are the finest and most sophisticated available. I question what the answers mean. I agree that the +2 BW is a statistical average; but an average of WHAT? A BW range of 0 to +4 has an average of +2; but so does a BW range of -18 to +22. What BW EPD range can we expect of this bull?

Ah, now we're getting somewhere. +2 BW is not a statistical average. It's the DIFFERENCE you would expect in the BW of calves sired by a bull with a +2 BW EPD AS COMPARED to a bull with a 0 BW EPD. It's that simple.

Sorry to burst your bubble, but if something is 30% "accurate" the reverse is also true! It is also 70% "inaccurate".

So 30% accuracy is not 30 times better than 0 accuracy? 70% inaccurate isn't better than 100% inaccurate?

 

[lakading]

So 30% accuracy is not 30 times better than 0 accuracy? 70% inaccurate isn't better than 100% inaccurate?

30 times 0 = 0!!!

Sorry, couldn't resist.

 

[Angus Guy]

Frankie and Jeanne you are correct in what you are saying. The WW and YW epd's will usually hold true. The thing I have noticed over the years is that BW does not always run true. My reasoning is alot goes into the calf in the last trimester of growth. The way a person feeds and what type of feed plus the amount of feed will have direct bearring on calf size. This usually happens with heifers more than cows. I have also noticed that with young bulls the BW can be way off. An example is a bull I raised with I-BW +4 has never thrown a calf over 70#. This was on cows and heifers. Had another bull I-BW +1 and pulled 1/2 of the heifers he bred. I guess what I'm saying is just use them as tools and watch the nutrition.

 

[lakading]

Frankie and Jeanne you are correct in what you are saying. The WW and YW epd's will usually hold true. The thing I have noticed over the years is that BW does not always run true. My reasoning is alot goes into the calf in the last trimester of growth. The way a person feeds and what type of feed plus the amount of feed will have direct bearring on calf size. This usually happens with heifers more than cows. I have also noticed that with young bulls the BW can be way off. An example is a bull I raised with I-BW +4 has never thrown a calf over 70#. This was on cows and heifers. Had another bull I-BW +1 and pulled 1/2 of the heifers he bred. I guess what I'm saying is just use them as tools and watch the nutrition.

Couldn't agree more!

 

[Aero]

Plus EPDs take environment and management out of the equation so that a bull that's creep fed won't have better EPDs than a bull that's not.

the only problem with this is when people take creep feeding to the next level. some places boasting 1000+ weaning weights have to be feeding some hot feed to get those weights. many of these bulls have WW EPDs higher than either of their parents.

 

[la4angus]

Plus EPDs take environment and management out of the equation so that a bull that's creep fed won't have better EPDs than a bull that's not.

the only problem with this is when people take creep feeding to the next level. some places boasting 1000+ weaning weights have to be feeding some hot feed to get those weights. many of these bulls have WW EPDs higher than either of their parents.

That is the reason for the Adj. 205 day WW.
An animal weighing 1000 lb at 8 1/2 mo on high energy creep ration is adjusted to 205 days without benefit of creep.

 

[lakading]

There is no adjustment made based on whether the animal is creep fed or not.

 

[la4angus]

There is no adjustment made based on whether the animal is creep fed or not.

Sure there is.

 

[Aero]

That is the reason for the Adj. 205 day WW.
An animal weighing 1000 lb at 8 1/2 mo on high energy creep ration is adjusted to 205 days without benefit of creep.

i understand the concept, but what i am saying is that there are different levels of creep feeding.all the AAA knows is if you checked yes or no on creep feeding. if i give them 5 lbs of soyhulls a day or give them 30 lbs of finishing ration a day, the weights get processed the same way. breeders that using the ultra high performance feeds can skew the EPDs beyond the genetic potential of the animal.

 

[lakading]

There is no adjustment made based on whether the animal is creep fed or not.

Sure there is.

No there isn't. Call the Association and ask. You simply select 1 or 3 when turning in weights to indicate a management code. This helps them ensure that calves are reported in accurate contemporary groups.

 

[Jeanne - Simme Valley]

Frankie and Jeanne you are correct in what you are saying. The WW and YW epd's will usually hold true. The thing I have noticed over the years is that BW does not always run true. My reasoning is alot goes into the calf in the last trimester of growth. The way a person feeds and what type of feed plus the amount of feed will have direct bearring on calf size. This usually happens with heifers more than cows. I have also noticed that with young bulls the BW can be way off. An example is a bull I raised with I-BW +4 has never thrown a calf over 70#. This was on cows and heifers. Had another bull I-BW +1 and pulled 1/2 of the heifers he bred. I guess what I'm saying is just use them as tools and watch the nutrition.

Yes, feed makes a big difference of BW, BUT, as we keep saying, EPD's are for you to COMPARE one bull to the next.
OK, you breed 1/2 your heifers to bull A that has a +2 BW epd, and 1/2 your heifers to bull B that has a +7 BW. ALL HEIFERS are FED EXACTLY the same way (pig fat or bone skinny). The heifers bred to Bull A 'SHOULD" average 5 pounds LIGHTER than the Bull B calves.
Now if you only breed 2 heifers, no, this won't happen. Odds are agains it, because remember the BW is affected by the dams genes. But over 100 'like' heifers, this is what you can EXPECT to happen.

 

[Jeanne - Simme Valley]

There is no adjustment made based on whether the animal is creep fed or not.

Sure there is.

There is NO ADJUSTMENT in the 205 Day Wt based on CREEP. They are adjusted by number of days old, and by age of dam. The creep info goes into the data base to be used to adjust the figures in the EPDs.
Even tho breeders creep feed, high or low, the calf crop figures are used only if there is at least two sires involved in the calf crop. SOOOO, the figures are used in COMPARISON of 1 sire over the other/others, besides just the actual weights.

 

[lakading]

Frankie and Jeanne you are correct in what you are saying. The WW and YW epd's will usually hold true. The thing I have noticed over the years is that BW does not always run true. My reasoning is alot goes into the calf in the last trimester of growth. The way a person feeds and what type of feed plus the amount of feed will have direct bearring on calf size. This usually happens with heifers more than cows. I have also noticed that with young bulls the BW can be way off. An example is a bull I raised with I-BW +4 has never thrown a calf over 70#. This was on cows and heifers. Had another bull I-BW +1 and pulled 1/2 of the heifers he bred. I guess what I'm saying is just use them as tools and watch the nutrition.

Yes, feed makes a big difference of BW, BUT, as we keep saying, EPD's are for you to COMPARE one bull to the next.
OK, you breed 1/2 your heifers to bull A that has a +2 BW epd, and 1/2 your heifers to bull B that has a +7 BW. ALL HEIFERS are FED EXACTLY the same way (pig fat or bone skinny). The heifers bred to Bull A 'SHOULD" average 5 pounds LIGHTER than the Bull B calves.
Now if you only breed 2 heifers, no, this won't happen. Odds are agains it, because remember the BW is affected by the dams genes. But over 100 'like' heifers, this is what you can EXPECT to happen.

Exactly right. However, I think maybe he meant that you could use a higher BW EPD bull without much trouble if you don't over feed.

 

[norriscathy]

I'm suprised some of the Associations haven't come in on this. I know they monitor this site. When I was writing about Gelbvieh tenderness I got a PM from the Gelbvieh Association. I think a little clarification from the Associations would be appreciated by all.

 

[Jeanne - Simme Valley]

I really don't think breed assn monitor this board.
I would venture to guess someone emailed them with your info & asked them to post to you. But, I could be wrong, maybe there are big eyes watching what we say about their breeds. :shock:

 

[norriscathy]

Big Brother is everywhere! Be Nice to All!!!!!!! Angus & Simis alike!

 

[Frankie]

I'm suprised some of the Associations haven't come in on this. I know they monitor this site. When I was writing about Gelbvieh tenderness I got a PM from the Gelbvieh Association. I think a little clarification from the Associations would be appreciated by all.

Gelbvieh have EPDs. If you're not satisfied with the information we've given you about EPDs, send them an email. Or probably any breed association would be glad to answer questions.