EPD question

[Frankie]

If bull A has WW of +42 and Bull B has WW of +20 EPD then a calf born from bull A "should" wean 42lb heavier than a calf born from bull B, having been bred to the same caow in the same environment. .

No. The calf sired by Bull A "should" weigh 22 more pounds at weaning than the calf born from Bull B. 42-20 = 22. If Bull B had a 0 WW EPD, you "should" expect the calf to weigh 42 more pounds at weaning.

For those totally confused now.

When the Angus Assn started EPDs, they took all the birthweights reported to the Assn in one particular year and averaged them. They did the same with WW and YW reported. That average was set as 0. It doesn't change from year to year. If a bull has a +5 BW EPD, it's +5 compared to the base of 0, not the current average of the breed (which is now +2.2).

Here are some links that explain how to use EPDs for those who are interested.

http://www.ext.vt.edu/pubs/beef/400-804/400-804.html

http://www.extension.umn.edu/Beef/compo ... esson3.pdf

http://www.angussiresearch.com/howto.html

 

[Sage]

Frankie yes you are right, got ahead of my self there. Subtract the EPD's from each bull to get the expected difference in the progeny. I got that fixed.

 

[Frankie]

Frankie yes you are right, got ahead of my self there. Subtract the EPD's from each bull to get the expected difference in the progeny. I got that fixed.

I know what you mean. It seems sometimes the more that I think about how they work, the harder it is to express it in words.

 

[Jeanne - Simme Valley]

Frankie, Sage & Dun are correct.
People get "breed average EPD's" and "base for EPD's" confused.
You look at BREED AVERAGE EPD's when you are trying to pick a bull to improve certain traits. You may want some lower than breed average or some traits higher, depending on your herd.
BASE for EPD's are how the Univ & Breed Assn's arrive at the EPD's - base year is different for most breeds, but they all equal each trait out to 0 - base year is 0 for each trait.
So bull A with +0 WW means it's performance is expected to be like it was when they set the base, and bull B with +40 is expected to produce offspring that will perform 40# heavier than the base year & Bull A.
I know what I want to say - not sure if this explains it well.

 

[OhioRiver]

Where can I find info about the ratios as compared to EPD's. Some ads do not put EPD's they put ratio;s how do I know what that would equate to on an EPD bar?

Production EPD's such as Birth, Weaning, Milk, Yearling are derived from multiple sources. I will not even guess how they do the calculations, However, Heres they way I understand it.
1. Weights/EPD's of the sire and his offsping are used 2. Dam and her offsring. 3. Actual weight and performance of the animal who is getting the numbers.
Production EPD's are expressed in pounds and is compared to breed Average. Example If you have a bull that is +100 for Yearling Weight. Assuming that breed average for YW is 1000 lbs. You have a Bull that could very well be 1100 lbs at yearling.
These numbers are not accurate in my book but they are a good tool to start with.
But if you are needing to get started. You can begin by calling your breed reps. It all takes diligint record keeping and is something done over time. I once bought the "perfect bull" who had no EPD's. It took to years of documenting his progeny before we started getting something to look at EPD wise.

EPDs don't compare to "average." EPD averages change with every sire summary. When AAA started EPDs, they established a baseline and EPDs are + or - compared to that base, not breed average. I assume other breeds did the same.

EPDs express what you expect from an animal's progeny, not from the bull himself. If you have a bull with a YW weight EPD of 100, you would expect his calves (progeny) to weigh 100 more pounds as yearlings than if you bred those same cows to a bull of the same breed with a YW EPD of 0. EPDs will never tell you what something will weigh. They just allow you to compare animals.

Contacting a breed rep is a good idea. Different breeds have different EPDs and a rep should be able to explain them.

 

[Frankie]

This explains contemporary groups and ratios for the AHIR program.

http://www.angus.org/performance/Docume ... bersCG.pdf

 

[novatech]

What throws me is this contemporary group thing.. There can be one contemporary group made up of 3 animals and another contemporary group made up of 100 animals. This does not seem like a proper way to come up with accurate info. when comparisons are made. Secondly what does one do when a calf is born and due to not falling into the proper calving time is all by itself. How can one get EPD's when there is no contemporary group?
If cattle are being compared to each other within a contemporary group and all of them are very good then how do you compare them to animal within another contemporary group of maybe poor quality cattle in a totally different environment. And those poor cattle are being compared to each other. And then you add the quantity thing in their to boot.
I can tell you this , Every time EPD discussion comes up more questions come up and the answers do more to confuse me.
The only thing I can tell is that I need to look for high accuracy scores before making any selections.

 

[Frankie]

What throws me is this contemporary group thing.. There can be one contemporary group made up of 3 animals and another contemporary group made up of 100 animals. This does not seem like a proper way to come up with accurate info. when comparisons are made.

Why not? They set a minimum contemporary group. There is no maximum. The better calf gets the higher ratio whether in a group of two or a group of 100. What difference does it make?

Secondly what does one do when a calf is born and due to not falling into the proper calving time is all by itself. How can one get EPD's when there is no contemporary group?

A calf either has EPDs when he's born or not. His own performance may affect those EPDs, but they don't "give" him EPDs. He may have Interim (I) EPDs, depending on his dam and sire's EPD status. That "I" will stay on his EPDs until data on his progeny are reported and his calves will not have any EPDs until the "I" is taken off. You need to pay attention to contemporary groupings long before the calves are born.

If cattle are being compared to each other within a contemporary group and all of them are very good then how do you compare them to animal within another contemporary group of maybe poor quality cattle in a totally different environment. And those poor cattle are being compared to each other. And then you add the quantity thing in their to boot.

You can compare cattle in different contemporary groups. But for AHIR reporting, they look strictly at how the animal looks within his contemporary group. That's how they strip out the management and enironment influence in EPDs.

I can tell you this , Every time EPD discussion comes up more questions come up and the answers do more to confuse me.
The only thing I can tell is that I need to look for high accuracy scores before making any selections.

They're not that hard to understand. You would expect a bull with a BW EPD of 5 to sire calves that weigh 5 lbs more at birth than if you bred those same cows to a bull with a BW EPD of 0. How hard is that? Using high accruacy sires is a good idea.

 

[rkm]

Sometimes I wish I was a drinking man. Then this would be so clear.

When we bred dairy we had PD and EPD etc. Although we need to how they come up with the numbers, it is more important to learn how to use them.

 

[novatech]

novatech wrote:
What throws me is this contemporary group thing.. There can be one contemporary group made up of 3 animals and another contemporary group made up of 100 animals. This does not seem like a proper way to come up with accurate info. when comparisons are made.


Why not? They set a minimum contemporary group. There is no maximum. The better calf gets the higher ratio whether in a group of two or a group of 100. What difference does it make?

When you are comparing only two it is a lot easier for to be better. When comparing 100 it is a lot tougher to move up the ladder. If you put both contemporary groups together to form only one group would the numbers remain the same? What is the low end animals numbers of one group in relation to the low end animals numbers of another group. You cannot come up with accuracy only comparing animals within a group, somehow you have to compare group to group.
The only way I see any accuracy on EPD's is years and years of records on progeny. By then the animals are dead and you are limited to AI

 

[rocket2222]

novatech wrote:
What throws me is this contemporary group thing.. There can be one contemporary group made up of 3 animals and another contemporary group made up of 100 animals. This does not seem like a proper way to come up with accurate info. when comparisons are made.


Why not? They set a minimum contemporary group. There is no maximum. The better calf gets the higher ratio whether in a group of two or a group of 100. What difference does it make?

When you are comparing only two it is a lot easier for to be better. When comparing 100 it is a lot tougher to move up the ladder. If you put both contemporary groups together to form only one group would the numbers remain the same? What is the low end animals numbers of one group in relation to the low end animals numbers of another group. You cannot come up with accuracy only comparing animals within a group, somehow you have to compare group to group.
The only way I see any accuracy on EPD's is years and years of records on progeny. By then the animals are dead and you are limited to AI

A contemporary group is made up of animals that are raised exactly the same way. If pick out 20 heifers for replacements out of a group of 100 heifers. Then you feed those 20 replacements grain, and the 80 heifers that are left are just left to graze your pastures untill they are big enough to sell to someone. You have made 2 contemporary groups. the 20 replacements you are feeding grain, and the 80 that are only getting grass. You would not want to have the calves on grain compared to the calves that just eat grass, it would not be a fair comparison. Thats why they are split in to different groups.