Earl Thigpen
Well-known member
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
--------------------------------------------------------------------------------
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.
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
--------------------------------------------------------------------------------
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.
