Difference between revisions of "Selection"

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Selection is the process of determining which animals will produce the next generation of offspring. Selection can happen at various stages of an animals life. Selection occurs for both males and females and includes decision such as [[Bull Selection | bull and semen purchases]], within herd [[Replacement Females | heifer retention or replacement heifer purchases]], [[Embryo Transfer | embryo donor cow]] selection and [[Cull Cows | cow culling]] decisions. Many factors can be involved in selection decisions such as confirmation, productivity, [https://articles.extension.org/sites/default/files/6_Color%20Patterns%20in%20Crossbred%20Beef%20Cattle_Arial_0.pdf color], [https://articles.extension.org/sites/default/files/2015-4_Genetics%20of%20Horned%20Polled%20and%20Scurred%20Cattle_Arial.pdf horned/polled/scurred] or other factors.
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Selection is the process of determining which animals will produce the next generation of offspring. Selection can happen at various stages of an animal's life. Selection occurs for both males and females and includes decision such as [[Bull Selection | bull and semen purchases]], within-herd [[Replacement Females | heifer retention or replacement heifer purchases]], [[Glossary#E| embryo donor cow]] selection and [[Cull Cows | cow culling]] decisions. Many factors can be involved in selection decisions such as confirmation, productivity, [https://articles.extension.org/sites/default/files/6_Color%20Patterns%20in%20Crossbred%20Beef%20Cattle_Arial_0.pdf color], [https://articles.extension.org/sites/default/files/2015-4_Genetics%20of%20Horned%20Polled%20and%20Scurred%20Cattle_Arial.pdf horned/polled/scurred] or other factors.
  
The progress made through selection is dependent on the genetic variation of the trait, accuracy of selection, selection intensity and generation interval. Traits with increased genetic variation increases the rate of genetic change. The ability to identify superior animals or increased accuracy of selection accelerates the rate of genetic change. Selection intensity refers to difference in the average genetic merit of the selected population compared to the entire population. Therefore, using a group of sires that average in the top 10% of the population for a trait would result in greater genetic change than using a group of bulls that averaged in the top 20% for that trait. Generation interval refers to the average age of the breeding animals; therefore, if a greater percentage of young animals are retained each year and older animals are culled then generation interval is decreased which will results in greater genetic change.
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The progress made through selection is dependent on the genetic variation of the trait, accuracy of selection, selection intensity and generation interval. Traits with increased genetic variation increases the rate of genetic change. The ability to identify superior animals or increased accuracy of selection accelerates the rate of genetic change. Selection intensity refers to the difference in the average genetic merit of the selected population compared to the entire population. Therefore, using a group of sires that average in the top 10% of the population for a trait would result in greater genetic change than using a group of bulls that averaged in the top 20% for that trait. Generation interval refers to the average age of the breeding animals; therefore, if a greater percentage of young animals are retained each year and older animals are culled then generation interval is decreased which will result in greater genetic change.

Revision as of 15:43, 9 November 2019

Selection is the process of determining which animals will produce the next generation of offspring. Selection can happen at various stages of an animal's life. Selection occurs for both males and females and includes decision such as bull and semen purchases, within-herd heifer retention or replacement heifer purchases, embryo donor cow selection and cow culling decisions. Many factors can be involved in selection decisions such as confirmation, productivity, color, horned/polled/scurred or other factors.

The progress made through selection is dependent on the genetic variation of the trait, accuracy of selection, selection intensity and generation interval. Traits with increased genetic variation increases the rate of genetic change. The ability to identify superior animals or increased accuracy of selection accelerates the rate of genetic change. Selection intensity refers to the difference in the average genetic merit of the selected population compared to the entire population. Therefore, using a group of sires that average in the top 10% of the population for a trait would result in greater genetic change than using a group of bulls that averaged in the top 20% for that trait. Generation interval refers to the average age of the breeding animals; therefore, if a greater percentage of young animals are retained each year and older animals are culled then generation interval is decreased which will result in greater genetic change.