Katahdin NSIP Breeder’s Group is a
group of Katahdin breeders using performance evaluation to obtain Expected Progeny
Differences (EPDs) on their breeding stock.
EPDs are by far the most accurate method of selecting and identifying
animals for either consistent or superior performance. The use of EPDs and the technology behind
them has dramatically changed the productivity of the beef, dairy and swine
industries in the USA
and also the sheep industries in the United
Kingdom and New
Zealand.
During 2006, we had 26 Katahdin breeders submitting data to
NSIP.
Contact
James
Morgan, PhD – Katahdin NSIP Data Coordinator
18235
Wildlife Rd
Fayetteville,
AR 72701
479-444-6075
jlmm@earthlink.net
The National Sheep Improvement Program (NSIP) is an
organization that does genetic evaluations for the purebred sheep industry in
the USA. The science behind the program
is provided by our NSIP Genetic Evaluation Center which is housed in Dr David
Notter’s Lab at Virginia Tech in Blackstone, VA. Dr Notter is a world-recognized leader in
genetic evaluation, especially for sheep.
In 2006, traits evaluated for the Katahdin breed include the
following EPDs (expected progeny differences).
60
day Weaning Wt (WW EPD) - explanation of – WW EPD
120
day Post-Weaning Wt (PW EPD) - explanation of – PW EPD
60
day Maternal Milk (MM EPD) -
explanation
of – MM EPD
60
day Milk + Growth (M+G EPD) - explanation of – M+G EPD
Percent
Lamb Crop (% LC EPD) -
explanation
of – %LC EPD
%
Weaned (%W EPD) -
explanation
of – %W EPD
Lbs
Lamb Weaned/ewe lambing (TWW EPD) - explanation
of – TWW EPD
Fecal
Egg Count – parasite resistance (FEC EPD) -
explanation of – FEC EPD
Predicted Error (measure of
accuracy) - explanation
of – Predicted Error
For a list of Katahdin Trait
Leaders, download the following file and/or print the following file.
2006 Katahdin NSIP Trait
Leaders
Data needed to participate are in
the following file.
Short Version
– Brief list of data to collect
Long
Version – Explanations about data needed. For those who like to know why.
DEFINITIONS/EXPLANATIONS OF TRAITS EVALUATED
1. The 60-Day Weaning Weight
EPD provides an estimate of preweaning growth potential.
2. The 120-Day
Postweaning Weight EPD combines information on preweaning and postweaning
growth to predict genetic merit for postweaning weight at 120 days.
3. The Maternal Milk EPD
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 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.
5. The Number Born, or Percent Lamb Crop, EPD 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.
CONTACT
James
Morgan, PhD – Katahdin NSIP Data Coordinator
18235
Wildlife Rd
Fayetteville,
AR 72701
479-444-6075
jlmm@earthlink.net