http://guidelines.beefimprovement.org/index.php?title=Selection_Index&feed=atom&action=historySelection Index - Revision history2024-03-29T11:28:58ZRevision history for this page on the wikiMediaWiki 1.35.2http://guidelines.beefimprovement.org/index.php?title=Selection_Index&diff=2327&oldid=prevBgolden at 17:40, 12 April 20212021-04-12T17:40:52Z<p></p>
<table class="diff diff-contentalign-left diff-editfont-monospace" data-mw="interface">
<col class="diff-marker" />
<col class="diff-content" />
<col class="diff-marker" />
<col class="diff-content" />
<tr class="diff-title" lang="en">
<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td>
<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 17:40, 12 April 2021</td>
</tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l1" >Line 1:</td>
<td colspan="2" class="diff-lineno">Line 1:</td></tr>
<tr><td colspan="2"> </td><td class='diff-marker'>+</td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">[[Category:Selection and Mating]]</ins></div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>The concept of a selection index was first described by a plant breeder, HFS Smith, in 1936<ref>Smith, F.H. 1936. A discriminant function for plant selection.</div></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>The concept of a selection index was first described by a plant breeder, HFS Smith, in 1936<ref>Smith, F.H. 1936. A discriminant function for plant selection.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Ann. Eugen. 7:240–250. doi:10.1111/j.1469-1809.1936. tb02143.x</ref>. He understood that the characters with which a plant breeder is principally concerned with are quantitative in nature, and that the interplay of genetics and environment made it difficult to discern the genotypic values of individual plants. Furthermore, he also understood that several desirable traits determined a line’s value (e.g., grain size, ear size, yield, protein content, etc.). Most importantly he opined that “…the actual worth to be attributed to each character is usually unknown.” He applied a statistical technique called a Discriminant Function to the traits he observed to help best indicate the “genetic value” of a plant.</div></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Ann. Eugen. 7:240–250. doi:10.1111/j.1469-1809.1936. tb02143.x</ref>. He understood that the characters with which a plant breeder is principally concerned with are quantitative in nature, and that the interplay of genetics and environment made it difficult to discern the genotypic values of individual plants. Furthermore, he also understood that several desirable traits determined a line’s value (e.g., grain size, ear size, yield, protein content, etc.). Most importantly he opined that “…the actual worth to be attributed to each character is usually unknown.” He applied a statistical technique called a Discriminant Function to the traits he observed to help best indicate the “genetic value” of a plant.</div></td></tr>
</table>Bgoldenhttp://guidelines.beefimprovement.org/index.php?title=Selection_Index&diff=2094&oldid=prevMnielsen at 15:27, 18 January 20202020-01-18T15:27:01Z<p></p>
<table class="diff diff-contentalign-left diff-editfont-monospace" data-mw="interface">
<col class="diff-marker" />
<col class="diff-content" />
<col class="diff-marker" />
<col class="diff-content" />
<tr class="diff-title" lang="en">
<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td>
<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 15:27, 18 January 2020</td>
</tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l44" >Line 44:</td>
<td colspan="2" class="diff-lineno">Line 44:</td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>''BIF recommends not using an ad hoc approach to the construction of selection indexes. Indexes should be created for seedstock and commercial producers that are economically optimal. If a breeding organization has a perceived marketing shortcoming, a well-defined desired gains approach should be used for breeding stock development.''</div></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>''BIF recommends not using an ad hoc approach to the construction of selection indexes. Indexes should be created for seedstock and commercial producers that are economically optimal. If a breeding organization has a perceived marketing shortcoming, a well-defined desired gains approach should be used for breeding stock development.''</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'>−</td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>==<del class="diffchange diffchange-inline">Citations</del>==</div></td><td class='diff-marker'>+</td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>==<ins class="diffchange diffchange-inline">References</ins>==</div></td></tr>
</table>Mnielsenhttp://guidelines.beefimprovement.org/index.php?title=Selection_Index&diff=1609&oldid=prevMnielsen at 21:27, 26 November 20192019-11-26T21:27:28Z<p></p>
<table class="diff diff-contentalign-left diff-editfont-monospace" data-mw="interface">
<col class="diff-marker" />
<col class="diff-content" />
<col class="diff-marker" />
<col class="diff-content" />
<tr class="diff-title" lang="en">
<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td>
<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 21:27, 26 November 2019</td>
</tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l10" >Line 10:</td>
<td colspan="2" class="diff-lineno">Line 10:</td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>indexes. Genetics 8:476–490.</ref>. He first defined the concept of aggregate genotype (H), or breeding objective in terms of the “…net genetic improvement which can be brought about by selecting among a group of animals is the sum of the genetic gains made for the several traits which have economic importance. It is logical to weight the gain made for each trait by the relative economic value of that trait”:</div></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>indexes. Genetics 8:476–490.</ref>. He first defined the concept of aggregate genotype (H), or breeding objective in terms of the “…net genetic improvement which can be brought about by selecting among a group of animals is the sum of the genetic gains made for the several traits which have economic importance. It is logical to weight the gain made for each trait by the relative economic value of that trait”:</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'>−</td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div><center><math>H=a_{1}G_{1}+a_{2}G_{2}+...+a_{<del class="diffchange diffchange-inline">n</del>}G_{<del class="diffchange diffchange-inline">n</del>}</math></center></div></td><td class='diff-marker'>+</td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><center><math>H=a_{1}G_{1}+a_{2}G_{2}+...+a_{<ins class="diffchange diffchange-inline">m</ins>}G_{<ins class="diffchange diffchange-inline">m</ins>}</math></center></div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>The <math>G_{i}</math> are the genetic values (or [[Expected Progeny Difference | EPD]]) for each trait and the <math>a_{i}</math> represent the marginal economic value (mev) for each trait. Hazel noted that the mev for each trait “…depends on the amount by which profit may be expected to increase for each unit improvement in that trait.” In other words, the mev measures the increase in profit that can be generated by adding an extra unit of input but holding all other values constant. This is a very similar approach to calculating derivatives of equations (as we will see later).</div></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>The <math>G_{i}</math> are the genetic values (or [[Expected Progeny Difference | EPD]]) for each trait and the <math>a_{i}</math> represent the marginal economic value (mev) for each trait. Hazel noted that the mev for each trait “…depends on the amount by which profit may be expected to increase for each unit improvement in that trait.” In other words, the mev measures the increase in profit that can be generated by adding an extra unit of input but holding all other values constant. This is a very similar approach to calculating derivatives of equations (as we will see later).</div></td></tr>
<tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l30" >Line 30:</td>
<td colspan="2" class="diff-lineno">Line 30:</td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>It is worth noting at this point that the traits recorded and which appear in the index do not need to be, and often are not, the same traits as those that appear in the aggregate genotype.</div></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>It is worth noting at this point that the traits recorded and which appear in the index do not need to be, and often are not, the same traits as those that appear in the aggregate genotype.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'>−</td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>In the previous section index development was based purely on phenotypic records. In reality, selection indexes developed by breed associations or other entities utilize [[Expected Progeny Difference | Expected Progeny Differences]] (EPD) weighted by economic values. EPD for each trait from genetic evaluation are first estimated, where all possible phenotypic information is utilized. Under this framework, it is assumed that multi-trait genetic evaluations are utilized to account for covariance between traits. The EPD are then combined with the economic values to derive the index.</div></td><td class='diff-marker'>+</td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>In the previous section<ins class="diffchange diffchange-inline">, </ins>index development was based purely on phenotypic records. In reality, selection indexes developed by breed associations or other entities utilize [[Expected Progeny Difference | Expected Progeny Differences]] (EPD) weighted by economic values. EPD for each trait from genetic evaluation are first estimated, where all possible phenotypic information is utilized. Under this framework, it is assumed that multi-trait genetic evaluations are utilized to account for covariance between traits. The EPD are then combined with the economic values to derive the index.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==Desired Gains Approach==</div></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==Desired Gains Approach==</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Performance recording and genetic evaluation services should be flexible, enabling the definition of breeding objectives in different ways, according to traits’ suitability and to breeders’ preferences. An optimal index is the sum of expected progeny differences (EPDs) for each economically relevant trait weighted by economic values and summed over all traits. </div></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Performance recording and genetic evaluation services should be flexible, enabling the definition of breeding objectives in different ways, according to traits’ suitability and to breeders’ preferences. An optimal index is the sum of expected progeny differences (EPDs) for each economically relevant trait weighted by economic values and summed over all traits. </div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'>−</td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>There will be instances in which the most appropriate course of action does not necessarily involve explicit use of economic values. For example, a breeding organization may have a perceived flaw that when corrected, would improve the marketability of its members' seed stock (e.g., [[Docility | docility]], [[Scrotal Circumference | scrotal circumference]], etc.). In these situations, a Desired Gains approach would be the most effective and technically sensible method to achieve genetic improvement. <ref>Pesek, J. and R. J. Baker. 1969. Desired improvement to selection</div></td><td class='diff-marker'>+</td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>There will be instances in which the most appropriate course of action does not necessarily involve explicit use of economic values. For example, a breeding organization may have a perceived flaw<ins class="diffchange diffchange-inline">, </ins>that when corrected, would improve the marketability of its members' seed stock (e.g., [[Docility | docility]], [[Scrotal Circumference | scrotal circumference]], etc.). In these situations, a Desired Gains approach would be the most effective and technically sensible method to achieve genetic improvement. <ref>Pesek, J. and R. J. Baker. 1969. Desired improvement to selection</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>indexes. Canadian J. Plant Sci. 49:803-804.</ref><ref>Itoh, Y. and Y. Yamada. 1986. Re-examination of selection index for desired gains. Genet. Sel. Evol. 18(4), 499-504.</ref> Desired Gains indexes do not require economic weights, and they do not maximize the correlation between the breeding objective and the index as optimum indexes do. An index constructed using pre-determined desired genetic gain will achieve breeding goals within a minimum number of generations. That said, the use of desired gains should not be a problem for breeders who are fully aware of the relative merits and potential shortcomings of their breeding stock.</div></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>indexes. Canadian J. Plant Sci. 49:803-804.</ref><ref>Itoh, Y. and Y. Yamada. 1986. Re-examination of selection index for desired gains. Genet. Sel. Evol. 18(4), 499-504.</ref> Desired Gains indexes do not require economic weights, and they do not maximize the correlation between the breeding objective and the index as optimum indexes do. An index constructed using pre-determined desired genetic gain will achieve breeding goals within a minimum number of generations. That said, the use of desired gains should not be a problem for breeders who are fully aware of the relative merits and potential shortcomings of their breeding stock.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l42" >Line 42:</td>
<td colspan="2" class="diff-lineno">Line 42:</td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==Index Construction BIF Guideline==</div></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==Index Construction BIF Guideline==</div></td></tr>
<tr><td class='diff-marker'>−</td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>''BIF recommends not using an ad hoc approach to the construction of selection indexes. Indexes should be created for commercial producers that are economically optimal. If a breeding organization has a perceived marketing shortcoming, a well-defined desired gains approach should be used for breeding stock development.''</div></td><td class='diff-marker'>+</td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>''BIF recommends not using an ad hoc approach to the construction of selection indexes. Indexes should be created for <ins class="diffchange diffchange-inline">seedstock and </ins>commercial producers that are economically optimal. If a breeding organization has a perceived marketing shortcoming, a well-defined desired gains approach should be used for breeding stock development.''</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==Citations==</div></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==Citations==</div></td></tr>
</table>Mnielsenhttp://guidelines.beefimprovement.org/index.php?title=Selection_Index&diff=1608&oldid=prevMnielsen at 21:20, 26 November 20192019-11-26T21:20:26Z<p></p>
<table class="diff diff-contentalign-left diff-editfont-monospace" data-mw="interface">
<col class="diff-marker" />
<col class="diff-content" />
<col class="diff-marker" />
<col class="diff-content" />
<tr class="diff-title" lang="en">
<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td>
<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 21:20, 26 November 2019</td>
</tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l12" >Line 12:</td>
<td colspan="2" class="diff-lineno">Line 12:</td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div><center><math>H=a_{1}G_{1}+a_{2}G_{2}+...+a_{n}G_{n}</math></center></div></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div><center><math>H=a_{1}G_{1}+a_{2}G_{2}+...+a_{n}G_{n}</math></center></div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'>−</td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>The <math>G_{i}</math> are the genetic values (or [[Expected Progeny Difference | EPD]]) for each trait and the <math><del class="diffchange diffchange-inline">u_</del>{i}</math> represent the marginal economic value (mev) for each trait. Hazel noted that the mev for each trait “…depends on the amount by which profit may be expected to increase for each unit improvement in that trait.” In other words, the mev measures the increase in profit that can be generated by adding an extra unit of input but holding all other values constant. This is a very similar approach to calculating derivatives of equations (as we will see later).</div></td><td class='diff-marker'>+</td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>The <math>G_{i}</math> are the genetic values (or [[Expected Progeny Difference | EPD]]) for each trait and the <math><ins class="diffchange diffchange-inline">a_</ins>{i}</math> represent the marginal economic value (mev) for each trait. Hazel noted that the mev for each trait “…depends on the amount by which profit may be expected to increase for each unit improvement in that trait.” In other words, the mev measures the increase in profit that can be generated by adding an extra unit of input but holding all other values constant. This is a very similar approach to calculating derivatives of equations (as we will see later).</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>In practice, the genetic values may be unknown (e.g., no EPD are available), but let us assume we record an animal’s phenotype for several traits and combine them into a selection index:</div></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>In practice, the genetic values may be unknown (e.g., no EPD are available), but let us assume we record an animal’s phenotype for several traits and combine them into a selection index:</div></td></tr>
</table>Mnielsenhttp://guidelines.beefimprovement.org/index.php?title=Selection_Index&diff=1607&oldid=prevMnielsen at 21:18, 26 November 20192019-11-26T21:18:37Z<p></p>
<table class="diff diff-contentalign-left diff-editfont-monospace" data-mw="interface">
<col class="diff-marker" />
<col class="diff-content" />
<col class="diff-marker" />
<col class="diff-content" />
<tr class="diff-title" lang="en">
<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td>
<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 21:18, 26 November 2019</td>
</tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l1" >Line 1:</td>
<td colspan="2" class="diff-lineno">Line 1:</td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>The concept of a selection index was first described by a plant breeder, HFS Smith, in 1936<ref>Smith, F.H. 1936. A discriminant function for plant selection.</div></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>The concept of a selection index was first described by a plant breeder, HFS Smith, in 1936<ref>Smith, F.H. 1936. A discriminant function for plant selection.</div></td></tr>
<tr><td class='diff-marker'>−</td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>Ann. Eugen. 7:240–250. doi:10.1111/j.1469-1809.1936. tb02143.x</ref>. He understood that the characters with which a plant breeder is principally concerned with are quantitative in nature, and that the interplay of genetics and environment made it difficult to discern the genotypic values of <del class="diffchange diffchange-inline">individuals </del>plants. Furthermore, he also understood that several desirable traits determined a line’s value (e.g., grain size, ear size, yield, protein content, etc.). Most importantly he opined that “…the actual worth to be attributed to each character is usually unknown.” He applied a statistical technique called a Discriminant Function to the traits he observed to help best indicate the “genetic value” of a plant.</div></td><td class='diff-marker'>+</td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>Ann. Eugen. 7:240–250. doi:10.1111/j.1469-1809.1936. tb02143.x</ref>. He understood that the characters with which a plant breeder is principally concerned with are quantitative in nature, and that the interplay of genetics and environment made it difficult to discern the genotypic values of <ins class="diffchange diffchange-inline">individual </ins>plants. Furthermore, he also understood that several desirable traits determined a line’s value (e.g., grain size, ear size, yield, protein content, etc.). Most importantly he opined that “…the actual worth to be attributed to each character is usually unknown.” He applied a statistical technique called a Discriminant Function to the traits he observed to help best indicate the “genetic value” of a plant.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>The notion of a single function composed of multiple traits in livestock was first described by Hazel and Lush in 1942<ref>Hazel, L.N., and J.L. Lush. 1942. The efficiency of three methods</div></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>The notion of a single function composed of multiple traits in livestock was first described by Hazel and Lush in 1942<ref>Hazel, L.N., and J.L. Lush. 1942. The efficiency of three methods</div></td></tr>
</table>Mnielsenhttp://guidelines.beefimprovement.org/index.php?title=Selection_Index&diff=1581&oldid=prevSnewman: /* Desired Gains Approach */2019-11-23T14:07:33Z<p><span dir="auto"><span class="autocomment">Desired Gains Approach</span></span></p>
<table class="diff diff-contentalign-left diff-editfont-monospace" data-mw="interface">
<col class="diff-marker" />
<col class="diff-content" />
<col class="diff-marker" />
<col class="diff-content" />
<tr class="diff-title" lang="en">
<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td>
<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 14:07, 23 November 2019</td>
</tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l35" >Line 35:</td>
<td colspan="2" class="diff-lineno">Line 35:</td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Performance recording and genetic evaluation services should be flexible, enabling the definition of breeding objectives in different ways, according to traits’ suitability and to breeders’ preferences. An optimal index is the sum of expected progeny differences (EPDs) for each economically relevant trait weighted by economic values and summed over all traits. </div></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Performance recording and genetic evaluation services should be flexible, enabling the definition of breeding objectives in different ways, according to traits’ suitability and to breeders’ preferences. An optimal index is the sum of expected progeny differences (EPDs) for each economically relevant trait weighted by economic values and summed over all traits. </div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'>−</td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>There will be instances in which the most appropriate course of action does not necessarily involve explicit use of economic values. For example, a breeding organization may have a perceived flaw that when corrected, would improve the marketability of <del class="diffchange diffchange-inline">their </del>seed stock (e.g., [[Docility | docility]], [[Scrotal Circumference | scrotal circumference]], etc.). In these situations, a Desired Gains approach would be the most effective and technically sensible method to achieve genetic improvement. <ref>Pesek, J. and R. J. Baker. 1969. Desired improvement to selection</div></td><td class='diff-marker'>+</td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>There will be instances in which the most appropriate course of action does not necessarily involve explicit use of economic values. For example, a breeding organization may have a perceived flaw that when corrected, would improve the marketability of <ins class="diffchange diffchange-inline">its members' </ins>seed stock (e.g., [[Docility | docility]], [[Scrotal Circumference | scrotal circumference]], etc.). In these situations, a Desired Gains approach would be the most effective and technically sensible method to achieve genetic improvement. <ref>Pesek, J. and R. J. Baker. 1969. Desired improvement to selection</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>indexes. Canadian J. Plant Sci. 49:803-804.</ref><ref>Itoh, Y. and Y. Yamada. 1986. Re-examination of selection index for desired gains. Genet. Sel. Evol. 18(4), 499-504.</ref> Desired Gains indexes do not require economic weights, and they do not maximize the correlation between the breeding objective and the index as optimum indexes do. An index constructed using pre-determined desired genetic gain will achieve breeding goals within a minimum number of generations. That said, the use of desired gains should not be a problem for breeders who are fully aware of the relative merits and potential shortcomings of their breeding stock.</div></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>indexes. Canadian J. Plant Sci. 49:803-804.</ref><ref>Itoh, Y. and Y. Yamada. 1986. Re-examination of selection index for desired gains. Genet. Sel. Evol. 18(4), 499-504.</ref> Desired Gains indexes do not require economic weights, and they do not maximize the correlation between the breeding objective and the index as optimum indexes do. An index constructed using pre-determined desired genetic gain will achieve breeding goals within a minimum number of generations. That said, the use of desired gains should not be a problem for breeders who are fully aware of the relative merits and potential shortcomings of their breeding stock.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td></tr>
</table>Snewmanhttp://guidelines.beefimprovement.org/index.php?title=Selection_Index&diff=1578&oldid=prevSnewman: /* Index Construction BIF Guideline */2019-11-22T20:02:22Z<p><span dir="auto"><span class="autocomment">Index Construction BIF Guideline</span></span></p>
<table class="diff diff-contentalign-left diff-editfont-monospace" data-mw="interface">
<col class="diff-marker" />
<col class="diff-content" />
<col class="diff-marker" />
<col class="diff-content" />
<tr class="diff-title" lang="en">
<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td>
<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 20:02, 22 November 2019</td>
</tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l42" >Line 42:</td>
<td colspan="2" class="diff-lineno">Line 42:</td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==Index Construction BIF Guideline==</div></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==Index Construction BIF Guideline==</div></td></tr>
<tr><td class='diff-marker'>−</td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>''BIF recommends not using an ad hoc approach to the construction of selection <del class="diffchange diffchange-inline">indices</del>. Indexes should be created for commercial producers that are economically optimal. If a breeding organization has a perceived marketing shortcoming, a well-defined desired gains approach should be used for breeding stock development.''</div></td><td class='diff-marker'>+</td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>''BIF recommends not using an ad hoc approach to the construction of selection <ins class="diffchange diffchange-inline">indexes</ins>. Indexes should be created for commercial producers that are economically optimal. If a breeding organization has a perceived marketing shortcoming, a well-defined desired gains approach should be used for breeding stock development.''</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==Citations==</div></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==Citations==</div></td></tr>
</table>Snewmanhttp://guidelines.beefimprovement.org/index.php?title=Selection_Index&diff=1577&oldid=prevSnewman: /* Desired Gains Approach */2019-11-22T15:53:47Z<p><span dir="auto"><span class="autocomment">Desired Gains Approach</span></span></p>
<table class="diff diff-contentalign-left diff-editfont-monospace" data-mw="interface">
<col class="diff-marker" />
<col class="diff-content" />
<col class="diff-marker" />
<col class="diff-content" />
<tr class="diff-title" lang="en">
<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td>
<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 15:53, 22 November 2019</td>
</tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l35" >Line 35:</td>
<td colspan="2" class="diff-lineno">Line 35:</td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Performance recording and genetic evaluation services should be flexible, enabling the definition of breeding objectives in different ways, according to traits’ suitability and to breeders’ preferences. An optimal index is the sum of expected progeny differences (EPDs) for each economically relevant trait weighted by economic values and summed over all traits. </div></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Performance recording and genetic evaluation services should be flexible, enabling the definition of breeding objectives in different ways, according to traits’ suitability and to breeders’ preferences. An optimal index is the sum of expected progeny differences (EPDs) for each economically relevant trait weighted by economic values and summed over all traits. </div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'>−</td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>There will be instances in which the most appropriate course of action does not necessarily involve explicit use of economic values. For example, a breeding organization may have a perceived flaw that when corrected, would improve the marketability of their seed stock (e.g., docility, scrotal circumference, etc.). In these situations, a Desired Gains approach would be the most effective and technically sensible method to achieve genetic improvement. <ref>Pesek, J. and R. J. Baker. 1969. Desired improvement to selection</div></td><td class='diff-marker'>+</td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>There will be instances in which the most appropriate course of action does not necessarily involve explicit use of economic values. For example, a breeding organization may have a perceived flaw that when corrected, would improve the marketability of their seed stock (e.g., <ins class="diffchange diffchange-inline">[[Docility | </ins>docility<ins class="diffchange diffchange-inline">]]</ins>, <ins class="diffchange diffchange-inline">[[Scrotal Circumference | </ins>scrotal circumference<ins class="diffchange diffchange-inline">]]</ins>, etc.). In these situations, a Desired Gains approach would be the most effective and technically sensible method to achieve genetic improvement. <ref>Pesek, J. and R. J. Baker. 1969. Desired improvement to selection</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>indexes. Canadian J. Plant Sci. 49:803-804.</ref><ref>Itoh, Y. and Y. Yamada. 1986. Re-examination of selection index for desired gains. Genet. Sel. Evol. 18(4), 499-504.</ref> Desired Gains indexes do not require economic weights, and they do not maximize the correlation between the breeding objective and the index as optimum indexes do. An index constructed using pre-determined desired genetic gain will achieve breeding goals within a minimum number of generations. That said, the use of desired gains should not be a problem for breeders who are fully aware of the relative merits and potential shortcomings of their breeding stock.</div></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>indexes. Canadian J. Plant Sci. 49:803-804.</ref><ref>Itoh, Y. and Y. Yamada. 1986. Re-examination of selection index for desired gains. Genet. Sel. Evol. 18(4), 499-504.</ref> Desired Gains indexes do not require economic weights, and they do not maximize the correlation between the breeding objective and the index as optimum indexes do. An index constructed using pre-determined desired genetic gain will achieve breeding goals within a minimum number of generations. That said, the use of desired gains should not be a problem for breeders who are fully aware of the relative merits and potential shortcomings of their breeding stock.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td></tr>
</table>Snewmanhttp://guidelines.beefimprovement.org/index.php?title=Selection_Index&diff=1576&oldid=prevSnewman: /* Desired Gains Approach */2019-11-22T15:47:46Z<p><span dir="auto"><span class="autocomment">Desired Gains Approach</span></span></p>
<table class="diff diff-contentalign-left diff-editfont-monospace" data-mw="interface">
<col class="diff-marker" />
<col class="diff-content" />
<col class="diff-marker" />
<col class="diff-content" />
<tr class="diff-title" lang="en">
<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td>
<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 15:47, 22 November 2019</td>
</tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l35" >Line 35:</td>
<td colspan="2" class="diff-lineno">Line 35:</td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Performance recording and genetic evaluation services should be flexible, enabling the definition of breeding objectives in different ways, according to traits’ suitability and to breeders’ preferences. An optimal index is the sum of expected progeny differences (EPDs) for each economically relevant trait weighted by economic values and summed over all traits. </div></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Performance recording and genetic evaluation services should be flexible, enabling the definition of breeding objectives in different ways, according to traits’ suitability and to breeders’ preferences. An optimal index is the sum of expected progeny differences (EPDs) for each economically relevant trait weighted by economic values and summed over all traits. </div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'>−</td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>There will be instances in which the most appropriate course of action does not necessarily involve explicit use of economic values. For example, a breeding organization may have a perceived flaw that when corrected, would improve the marketability of their seed stock (e.g., docility, scrotal circumference, etc.). In these situations, a Desired Gains approach would be the most effective and technically sensible method to achieve genetic improvement <ref>Pesek, J. and R. J. Baker. 1969. Desired improvement to selection</div></td><td class='diff-marker'>+</td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>There will be instances in which the most appropriate course of action does not necessarily involve explicit use of economic values. For example, a breeding organization may have a perceived flaw that when corrected, would improve the marketability of their seed stock (e.g., docility, scrotal circumference, etc.). In these situations, a Desired Gains approach would be the most effective and technically sensible method to achieve genetic improvement<ins class="diffchange diffchange-inline">. </ins><ref>Pesek, J. and R. J. Baker. 1969. Desired improvement to selection</div></td></tr>
<tr><td class='diff-marker'>−</td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>indexes. Canadian J. Plant Sci. 49:803-804.</ref><ref>Itoh, Y. and Y. Yamada. 1986. Re-examination of selection index for desired gains. Genet. Sel. Evol. 18(4), 499-504.</ref><del class="diffchange diffchange-inline">. </del>Desired Gains indexes do not require economic weights, and they do not maximize the correlation between the breeding objective and the index as optimum indexes do. An index constructed using pre-determined desired genetic gain will achieve breeding goals within a minimum number of generations. That said, the use of desired gains should not be a problem for breeders who are fully aware of the relative merits and potential shortcomings of their breeding stock.</div></td><td class='diff-marker'>+</td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>indexes. Canadian J. Plant Sci. 49:803-804.</ref><ref>Itoh, Y. and Y. Yamada. 1986. Re-examination of selection index for desired gains. Genet. Sel. Evol. 18(4), 499-504.</ref> Desired Gains indexes do not require economic weights, and they do not maximize the correlation between the breeding objective and the index as optimum indexes do. An index constructed using pre-determined desired genetic gain will achieve breeding goals within a minimum number of generations. That said, the use of desired gains should not be a problem for breeders who are fully aware of the relative merits and potential shortcomings of their breeding stock.</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==Ad Hoc Index==</div></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==Ad Hoc Index==</div></td></tr>
</table>Snewmanhttp://guidelines.beefimprovement.org/index.php?title=Selection_Index&diff=1575&oldid=prevSnewman: /* Index Construction BIF Guideline */2019-11-22T15:36:42Z<p><span dir="auto"><span class="autocomment">Index Construction BIF Guideline</span></span></p>
<table class="diff diff-contentalign-left diff-editfont-monospace" data-mw="interface">
<col class="diff-marker" />
<col class="diff-content" />
<col class="diff-marker" />
<col class="diff-content" />
<tr class="diff-title" lang="en">
<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td>
<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 15:36, 22 November 2019</td>
</tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l42" >Line 42:</td>
<td colspan="2" class="diff-lineno">Line 42:</td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==Index Construction BIF Guideline==</div></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==Index Construction BIF Guideline==</div></td></tr>
<tr><td class='diff-marker'>−</td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>''BIF recommends not using ad hoc construction of selection indices. Indexes should be created for commercial producers that are economically optimal. If a breeding organization has a perceived marketing shortcoming, a well defined desired gains approach should be used for breeding stock development.''</div></td><td class='diff-marker'>+</td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>''BIF recommends not using <ins class="diffchange diffchange-inline">an </ins>ad hoc <ins class="diffchange diffchange-inline">approach to the </ins>construction of selection indices. Indexes should be created for commercial producers that are economically optimal. If a breeding organization has a perceived marketing shortcoming, a well<ins class="diffchange diffchange-inline">-</ins>defined desired gains approach should be used for breeding stock development.''</div></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"></td></tr>
<tr><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==Citations==</div></td><td class='diff-marker'> </td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==Citations==</div></td></tr>
</table>Snewman