EPD's in General

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Earl Thigpen

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Folks, I ran across this article this morning and found it very informative in some aspect and more confusing in others. I am not a user of EPD's or at least never have been. But I am venturing out a little into registered livestock and it appears I need to get up to speed on EPD's, what they mean, what's the accuracy, how to use them and more importantly, how to create them.

One comment in this article is on the accuracy of the EPD numbers. It would seem that the only assurance of an accuracy of 90% or better is to have established a long line of historical data (years and generations) of a given herd. It would seem that for someone just getting into the high bred cattle business that EPD's, while they might be good indicators of the offspring traits, the accuracy would be less than 50% or stated another way, almost useless.

I would sure like to hear some of your opinions on EPD's and how they are used. Please keep in mind that while my family has been in the cattle business for four or five generations we have never gone beyond raising calves for the commercial market. And I don't want folks who are in the same business to feel I just slammed them - cut me some slack. I personally just want to expand a little, have more fun and maybe, just maybe, make a little money in the process.


EPDs - How to use the animal & EPD search forms
How to read the results
Statistics

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How to read the results

EPD’s are an estimate of an animal's genetic worth for that particular trait. An EPD is expressed in the units of measure for that trait. EPD’s are based on a combination of performance information from an animal's pedigree, individual and progeny performance. EPD’s can be used to predict one animal's progeny performance compared to another's progeny. EPD’s can also be used to compare the genetic worth of one animal to the overall Hereford population average and distribution. Each calculated EPD has an associated accuracy value.

An accuracy value calculated by the genetic analysis is a number between 0 and 1. Accuracy is a relative indicator of the confidence you can place in that particular EPD. The closer an accuracy is to one, the more reliable is the estimate.

Accuracy ranges from 0-99% and indicates the probability of an EPD changing with the addition of more progeny data. The magnitude of possible change decreases as accuracy increases. Accuracy below 75% should be regarded as low, between 76-90% as medium and above 90% as high.

An EPD with an accuracy of "P" is "Pedigree Estimate" and is simply the exact average of that animal's parents. An EPD with an accuracy of "P+" is an "Interim EPD" and is the parental average adjusted by the animal's individual performance compared to his contemporaries.

Accuracy is based on the amount of performance information available on the animal and its close relatives - particularly the number of progeny analyzed. Accuracy is also based on the heritability of the trait and the genetic correlations with other recorded traits. Hence accuracy indicates the "confidence level" of the EPD.

Regn. No: The Association Registration Number of the animal.

Name: The registered name of the animal.

Calving Ease – Direct (CE) :
CE EPDs are based on calving ease scores and birth weights. More positive EPDs are favorable and indicate easier calving. The EPD for direct calving ease indicates the influence of the sire on calving ease in purebred females calving at two years of age.

Birth Weight (BW) :
The BW EPD is an indicator of birth weight and calving ease. Progeny sired by a bull with a BW EPD of 2.2 can be expected to weigh 3.2 lb. more at birth, on average, than progeny sired by a bull with an EPD of -1.0 lb. (2.2 minus -1.0 = 3.2 lb.) Birth weight is another indicator of calving ease. Larger BW EPDs usually, but not always, indicate more calving difficulty.

Weaning Weight (WW) :
The WW EPD reflects pre-weaning growth potential. Measured from adjusted 205-day weight. It is an indicator of direct genes for growth independent of milk production of the dam. Calves sired by a bull with a WW EPD of 30 should have a 20 lb. advantage in 205-day adjusted weaning weight compared to calves sired by a bull with an EPD of +10 lb. (30 minus 10.0 = 20 lb.).

Yearling Weight (YW) :
YW EPD for a sire with an EPD of 87 indicates that on average, his progeny should be 30 lb. above the average of progeny of a bull with an EPD of 57 lb. YW EPD reflects differences in the 365-day adjusted yearling weight for progeny. It is the best estimate of total growth.

Maternal Milk (MM) :
The MM EPD is a prediction of weaning weight differences due to milk and maternal ability of the dam. For a sire, the MM EPD predicts the maternal ability of his daughters expressed in pounds of calf weaned. MM EPD’s do not specifically predict pounds of milk produced, but pounds of calf weaned due to maternal production of the dam. It predicts the difference in average weaning weight of sires’ daughters’ progeny due to milking ability. Daughters of a sire with a MM EPD of 14 should produce progeny with 205-day weights averaging 24 lb. more (as a result of greater milk production) than daughters of a bull with a MM EPD of -10 lb. (14 minus -10.0 = 24 lb.). This difference in weaning weight is due to total milk production over the entire lactation period.

Maternal Milk & Growth (MG) :
The MG EPD is a combination EPD. It is the MM EPD plus 1/2 the WW EPD. It has no accuracy value since it is simply a combination of two other EPD’s. A sire's MG EPD reflects what he is expected to transmit to his daughters for a combination of both growth genetics (WW EPD) and maternal production (MM EPD). This EPD is sometimes referred to as “total maternal” or “combined maternal.”

Maternal Calving Ease (MCE)
The MCE EPD indicates how easily a sire's daughters will calve at two years of age. When compared to the daughters of other sires.

Scrotal Circumference (SC) :
Measured in centimeters and adjusted to 365 days of age, SC EPD is the best estimate of fertility. It is related to the bull's own semen quantity and quality, and is also associated with age at puberty of sons and daughters. Larger SC EPDs suggest younger age at puberty. Yearling sons of a sire with an EPD of 0.7 should have yearling scrotal circumference measurements that average 0.7 cm. larger than progeny by a bull with an EPD of 0.0. In this genetic analysis, a multiple-trait model was used for scrotal circumference. Weaning weight was used as a predictor variable to increase the prediction accuracy of SC EPDs. Therefore, an animal with a weaning weight EPD should also have an SC EPD.

Rib Fat (FAT) :
The FAT EPD reflects differences in adjusted 365-day, twelfth-rib fat thickness based on ultrasound measurements of live yearling cattle. Sires with low, or negative, FAT EPDs are expected to produce leaner progeny than sires with higher EPDs. Ultrasound measures have been shown to be highly correlated with the performance of slaughter progeny.

Ribeye Area (REA) :
REA EPDs reflect differences in an adjusted 365-day ribeye area measures based on ultrasound measurements of live yearling cattle. Sires with relatively higher REA EPDs are expected to produce better muscled and higher percentage yielding slaughter progeny than will sires with lower REA EPDs

Intramuscular Fat (IMF) :
IMF EPDs reflect differences in an adjusted 365-day intramuscular fat (marbling) score based on ultrasound measurements of live yearling cattle. Breeding cattle with higher IMF EPD’s should produce slaughter progeny with a higher degree of intramuscular fat and therefore higher quality grades.
 
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Earl Thigpen

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dun":3gfuya6o said:
I didn;t follow the question, sorry!

What good are the EPD's on new, developing herds if the accuracy of the EPD is very low? How do you measure EPD's on new herds if the petigree of your stock only goes back say two generations?

As you can tell, I know absolutely nothing about the use of EPD's so be gentle. :lol: And thanks for your response.
 

dun

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Earl Thigpen":3jevnptp said:
What good are the EPD's on new, developing herds if the accuracy of the EPD is very low? How do you measure EPD's on new herds if the petigree of your stock only goes back say two generations?

Even in "developing herds the genetics had to come from somewhere. If EPDs are available for an animal you can follow that back many generations. A new born animal has just P or I EPDs, depends on the breed. But it's sire and dam will have EPDs with "some" accuracy.
I consider anything under 80% pretty much a crapshoot and have to know a cow well before I use that bull on her. The Red Angus site has a table that (for that breed) lists the possible vartiation of each trait based on the accuracy. I'll try to find it again. One of the catch in the butt deals about EPDs that is rarely mentioned is that even with a .99 accuracy that only (based on the bell curve) accounts for 66% of the matings. So in really it .99 is only 66% accurate.
 

Frankie

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Earl Thigpen":2kvm88t2 said:
Folks, I ran across this article this morning and found it very informative in some aspect and more confusing in others. I am not a user of EPD's or at least never have been. But I am venturing out a little into registered livestock and it appears I need to get up to speed on EPD's, what they mean, what's the accuracy, how to use them and more importantly, how to create them.

One comment in this article is on the accuracy of the EPD numbers. It would seem that the only assurance of an accuracy of 90% or better is to have established a long line of historical data (years and generations) of a given herd. It would seem that for someone just getting into the high bred cattle business that EPD's, while they might be good indicators of the offspring traits, the accuracy would be less than 50% or stated another way, almost useless.

I would sure like to hear some of your opinions on EPD's and how they are used. Please keep in mind that while my family has been in the cattle business for four or five generations we have never gone beyond raising calves for the commercial market. And I don't want folks who are in the same business to feel I just slammed them - cut me some slack. I personally just want to expand a little, have more fun and maybe, just maybe, make a little money in the process.

Why would anyone slam you for trying to learn about EPDs....and make a few bucks? Not me. We had commercial cattle before we had registered. Many large seedstock operations also run commercial herds.

One reason we bought our first Angus bull was because, at that time, Angus was about the only breed pushing EPDs and their use. Frankly, EPDs seemed like a no brainer to newbies in the cattle business like us. Since then, every serious beef breed has come up with their own EPDs and commercial cattlemen have accepted them for making breeding decisions in their herd.

We've defended EPDs to commercial producers and spent some time educating commercial producers on EPDs over the years. One incident always stands out in my mind. We had gone to the first production sale of a young couple who had just got into the Angus business. We were already seated in the stands when two potential buyers sat down beside us. They had looked at the bulls, marked several, and were looking the rest of the catalog over. One of them asked if we knew what those numbers meant? You could see a light come on in his head as it was explained that you'd expect the calf sired by a bull with a WW of 15 to weigh 15 more pounds at weaning than a calf sired by a bull with a WW EPD of 0, all other things being equal. They looked back at their bull selections and decided to go back out and look the bulls over again. The stands filled up and we didn't see them again, so I don't know if they bought a bull. But, I'd bet money on it that those guys are using EPDs today to make their bull selections. EPDs aren't the silver bullet, but to ignore them is like leaving the screwdrive out of your tool box.

Accuracies are very important. It does take generations to collect data for reliable EPDs. No matter how much data is reported, the Angus Assn keeps accuracies on bulls at .85 until they're widely used. That way a breeder can't get the accuracies of his bull's good EPDs up by just reporting his good calves. Generally speaking, we'll wait for a bull to get above .85 before we use him. But with the deep performance pedigrees we see on Angus bulls, you can be pretty confident that the EPDs are reliable. And we pay attention to the breeder. IMO, some breeders are more trustworthy than others.

You don't say what breed you're raising, but EPDs on Angus aren't based on one herd. EPDs are compiled by the AAA and use data from breeders across the US.

I'd encourage you to join the breed association, spend some time reading all their literature on the breed, attending state and regional meetings of the breed, perhaps even serve on a Board. Attend whatever sales you can get to. Introduce yourself to people, look over bulls of various bloodlines, talk to commercial bull buyers. Raising registered stock can be a lot of fun and we've made money in the business. It's changed a lot over the 20+ years we've been doing it, but it's been a rewarding experience. :D
 

LoveMoo11

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Honestly, we have always had registered cattle and have never used EPDs. We still have great quality cattle-its just a matter of preference. When matching sires, I always use my eyes-what does my cow lack that I would like to add to a calf? That's what I look for in a bull.
 
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Earl Thigpen

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Thanks for the info, Dun.

I just bought a registered Red Angus bull last week and getting ready to look at another one next week.

When the owner of the bull I just bought whipped out the EPD sheet and pedigree all I could do was nod my head and try not to look too stupid which, by the way, is pretty difficult for me. I need to edumicate myself - quickly.

I like the comment about the 60% of 90%. As you know in my day job I have to deal with the reliability of electronic components and assemblies used in an oil well borehole. In one of the software packages we use there is a "confidence level" that is attached to every reliability statement. Goes something like this." We have asertained with a 60% confidence level that your product will operate in the prescribed environment 90% of the time." Boy, talk about a golden parachute!

Anyway, thanks again. I'm sure I will have more dumb questions.
 

novatech

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LoveMoo11":u5f6dnd1 said:
Honestly, we have always had registered cattle and have never used EPDs. We still have great quality cattle-its just a matter of preference. When matching sires, I always use my eyes-what does my cow lack that I would like to add to a calf? That's what I look for in a bull.
Go down a list of EPS and tell me how many of the items on them your eyes can determine with any type of accuracy. More importantly, list the ones you cannot see.
I had pretty much the same attitude until I learned more about them and how I could benefit from them.
I think it is human nature to dismiss thinks we do not know or understand, especially when we have done it different way for so long.
 

Aero

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Earl:
Acc is pretty simple. it only comes from 3 places: 1) parental EPDs, 2) individual performance, 3) progeny perofrmance.

when a calf is first registered w/ AAA, if the parents have better than .05 for Acc of a particular EPD, the parents EPDs will be averaged. this carries little weight but is just meant to be a guess. as you turn in performance records (BW, WW, etc) the animals own performance will increase the Acc (usually up to about .30) for the measurement turned in. when this particular animal has offspring, the same measurements of offspring will take the Acc up even further.

Acc has nothing to do with how new anything is; it's just a number representing how much performance information has been gathered.
 

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