| DEFINITIONS/EXPLANATIONS OF TRAITS EVALUATED Uncompahgre Polypay Farm The home of production Polypays |
The following is from the Katahdin’s NSIP. I think they have done a good job of describing the traits.
Polypays do not have traits 6, 7 & 9. It seems to me that trait 6 and 7 are important and needed by our
breed.
1. The 60-Day Weaning Weight EPD (WW) provides an estimate of preweaning growth potential.
2. The 120-Day Postweaning Weight EPD (PWW) combines information on preweaning and postweaning
growth to predict genetic merit for postweaning weight at 120 days.
3. The Maternal Milk EPD (MM) provides an indication of the genetic merit for mothering ability. This EPD
primarily reflects genetic differences in ewe milk production potential as realized in her lambs. The maternal milk
EPD is thus expressed in pounds of lamb weaned, not pounds of milk produced. It is derived by evaluating if
individual ewes produce lambs that do better or worse than expected based on the weaning weight EPDs of the
parents. Ewes whose lambs grow faster to weaning than predicted are assumed to be better milk producers
whereas ewes whose lambs grow more slowly than predicted to weaning are assumed to produce less milk. This
relationship between maternal milk EPD and actual milk production has been validated in beef cattle and is
assumed to be similar in sheep, although other elements of maternal behavior may also be included in the
maternal milk EPD. Selection for high maternal milk EPDs is anticipated to improve milk production and mothering
ability in the flock.
4. The Milk plus Growth EPD (MGR) combines information on weaning weight and maternal milk EPDs to
provide an index of the total anticipated contribution of an animal's daughters to lamb weaning weight. The milk
plus growth EPD is calculated as the sum of the maternal milk EPD plus one half the weaning weight EPD. It
recognizes that the genetic contribution of a ewe to the weaning weight of her lambs combines the effects of her
milk production (measured by the maternal milk EPD) and a sample one half of her genes for preweaning growth
potential (measured by the weaning weight EPD). Because the milk plus growth EPD is calculated from two other
EPDs, an accuracy value is not reported for this EPD. This deals with the second generation or “grandlambs”.
5. The Number Born, or Percent Lamb Crop, EPD (NB) evaluates genetic potential for prolificacy. This EPD
is expressed as numbers of lambs born per 100 ewes lambing. An EPD of +5.0 for percent lamb crop thus
indicates that an animal is expected to produce daughters who will have an average of .05 more lambs at each
lambing, or 5.0 more lambs per 100 lambings, than an average ewe. Selection on percent lamb crop EPD is
expected to increase prolificacy in the flock.
6. The Number Weaned EPD evaluates the genetic potential for prolificacy and maternal genetic effects on
lamb survival. This EPD primarily reflects the ability of animals to have and raise lambs and is expressed as
numbers of lambs weaned per 100 ewes lambing. An EPD of +5.0% indicates that an animal is expected to
produce daughters who will wean an average of 0.05 more lambs at each lambing than a ewe with an EPD of 0.0.
7. The Total Pounds Weaned EPD provides a combined measure of genetic merit for prolificacy, rearing
ability, and growth. An EPD of +10.0 lb indicates that an animal is expected to produce daughters who will, on
average, wean 10 lb more lamb at each lambing than the daughters of an average animal. This EPD should be
used to select animals to improve total pounds weaned in the next generation.
8. The Total Pounds Weaned Producing Ability (PA) is a measure of future performance of a ewe with
respect to the pounds of lamb that she will wean. It is a combined effect of her genetic merit and nongenetic
permanent environmental effects that influence future production. A PA of +15.0 lb indicates that a ewe is
expected, on average, to wean 15 lb more lamb than an average ewe at her next lambing opportunity. The PA is
affected by both genetic and nongenetic factors and should be used to culling tool to identify ewes with poor
expected future performance.
9. The Fecal Egg Count EPD is a measure of parasite resistance. Leading sires for this trait sired lambs
with lower fecal egg counts than the breed average. Increased resistance is noted by a more negative value.
The level set for the zero point of this trait is 2000 eggs per gram using the McMaster’s method of counting
nematode (strongyle) eggs. A positive EPD indicates a sire will pass on genetics for less resistance and a
negative value will indicate a sire that is predicted to pass on more parasite resistance.
10. EPDs & Predicted Error (PE) - An EPD for an animal can be though of as an estimate of performance
surrounded by error. The prediction error quantifies the magnitude of that error. The properties of prediction
error can be summarized relatively easily: There is about one chance in three (a probability of about .33) that an
animal's EPD for a given trait will change (either increase or decrease) by more than the amount of the prediction
error. EPDs are predicted and the predicted error provides an estimate of how much the EPD will change as
more information on the performance of these animals offspring are evaluated in future years. The predicted
error is provided for all EPDs except Milk + Growth. The predicted error is placed in parentheses with the EPD.
Polypays do not have traits 6, 7 & 9. It seems to me that trait 6 and 7 are important and needed by our
breed.
1. The 60-Day Weaning Weight EPD (WW) provides an estimate of preweaning growth potential.
2. The 120-Day Postweaning Weight EPD (PWW) combines information on preweaning and postweaning
growth to predict genetic merit for postweaning weight at 120 days.
3. The Maternal Milk EPD (MM) provides an indication of the genetic merit for mothering ability. This EPD
primarily reflects genetic differences in ewe milk production potential as realized in her lambs. The maternal milk
EPD is thus expressed in pounds of lamb weaned, not pounds of milk produced. It is derived by evaluating if
individual ewes produce lambs that do better or worse than expected based on the weaning weight EPDs of the
parents. Ewes whose lambs grow faster to weaning than predicted are assumed to be better milk producers
whereas ewes whose lambs grow more slowly than predicted to weaning are assumed to produce less milk. This
relationship between maternal milk EPD and actual milk production has been validated in beef cattle and is
assumed to be similar in sheep, although other elements of maternal behavior may also be included in the
maternal milk EPD. Selection for high maternal milk EPDs is anticipated to improve milk production and mothering
ability in the flock.
4. The Milk plus Growth EPD (MGR) combines information on weaning weight and maternal milk EPDs to
provide an index of the total anticipated contribution of an animal's daughters to lamb weaning weight. The milk
plus growth EPD is calculated as the sum of the maternal milk EPD plus one half the weaning weight EPD. It
recognizes that the genetic contribution of a ewe to the weaning weight of her lambs combines the effects of her
milk production (measured by the maternal milk EPD) and a sample one half of her genes for preweaning growth
potential (measured by the weaning weight EPD). Because the milk plus growth EPD is calculated from two other
EPDs, an accuracy value is not reported for this EPD. This deals with the second generation or “grandlambs”.
5. The Number Born, or Percent Lamb Crop, EPD (NB) evaluates genetic potential for prolificacy. This EPD
is expressed as numbers of lambs born per 100 ewes lambing. An EPD of +5.0 for percent lamb crop thus
indicates that an animal is expected to produce daughters who will have an average of .05 more lambs at each
lambing, or 5.0 more lambs per 100 lambings, than an average ewe. Selection on percent lamb crop EPD is
expected to increase prolificacy in the flock.
6. The Number Weaned EPD evaluates the genetic potential for prolificacy and maternal genetic effects on
lamb survival. This EPD primarily reflects the ability of animals to have and raise lambs and is expressed as
numbers of lambs weaned per 100 ewes lambing. An EPD of +5.0% indicates that an animal is expected to
produce daughters who will wean an average of 0.05 more lambs at each lambing than a ewe with an EPD of 0.0.
7. The Total Pounds Weaned EPD provides a combined measure of genetic merit for prolificacy, rearing
ability, and growth. An EPD of +10.0 lb indicates that an animal is expected to produce daughters who will, on
average, wean 10 lb more lamb at each lambing than the daughters of an average animal. This EPD should be
used to select animals to improve total pounds weaned in the next generation.
8. The Total Pounds Weaned Producing Ability (PA) is a measure of future performance of a ewe with
respect to the pounds of lamb that she will wean. It is a combined effect of her genetic merit and nongenetic
permanent environmental effects that influence future production. A PA of +15.0 lb indicates that a ewe is
expected, on average, to wean 15 lb more lamb than an average ewe at her next lambing opportunity. The PA is
affected by both genetic and nongenetic factors and should be used to culling tool to identify ewes with poor
expected future performance.
9. The Fecal Egg Count EPD is a measure of parasite resistance. Leading sires for this trait sired lambs
with lower fecal egg counts than the breed average. Increased resistance is noted by a more negative value.
The level set for the zero point of this trait is 2000 eggs per gram using the McMaster’s method of counting
nematode (strongyle) eggs. A positive EPD indicates a sire will pass on genetics for less resistance and a
negative value will indicate a sire that is predicted to pass on more parasite resistance.
10. EPDs & Predicted Error (PE) - An EPD for an animal can be though of as an estimate of performance
surrounded by error. The prediction error quantifies the magnitude of that error. The properties of prediction
error can be summarized relatively easily: There is about one chance in three (a probability of about .33) that an
animal's EPD for a given trait will change (either increase or decrease) by more than the amount of the prediction
error. EPDs are predicted and the predicted error provides an estimate of how much the EPD will change as
more information on the performance of these animals offspring are evaluated in future years. The predicted
error is provided for all EPDs except Milk + Growth. The predicted error is placed in parentheses with the EPD.
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