LAMBPLAN Selection Index
A LAMBPLAN breed selection index is designed to monitor those Estimated Breeding Values (EBVs) which are important to measuring the overall productivity usefulness of a specific sheep. Since the Clun Forest is a maternal breed, the NACFA has decided that certain maternal productivity traits that demonstrate ease of lambing, mothering ability, high twinning rates, and strong rates of growth are the most important traits we can measure.
Looking at individual EBVs is useful in selecting sheep for individual traits, but the Selection Index gives us a "bundle" of important traits in a weighted average (some traits carry more weight than others). The composite weighted scores of the traits listed below make up the NACFA Selection Index (SI). The index is calibrated so that an SI score of 100 should be the breed average. ).
|
Trait Measured |
EBV |
SI Index % |
Economic
Weighted |
Estimated gain over 10 years of selection |
|
weaning weight |
wwt |
29% |
0.55 |
1.7 kg |
|
maternal weaning weight |
mwwt |
11% |
3.00 |
0.5 kg |
|
post-weaning weight |
pwt |
31% |
1.25 |
2.3 kg |
|
number of lambs weaned |
nlw |
28% |
60.00 |
11% |
Note that the weighted number is meaningless by itself, however it is the result of taking our SI index percentage for a particular EBV and making calculations on heritability, etc to generate a weighted number which should be inserted in to the "index calculator" of the pedigree wizard software. Once those EBVs and weighted numbers are added to the index calculator, the index can be saved on your computer as the "Clun Forest" selection index.
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