Presentation on theme: "Livestock Improvement through Selection"— Presentation transcript:
1 Livestock Improvement through Selection Learn all genetic traits!!!!
2 Objectives Compare and contrast the idea of genetics vs environment List examples of high and low heritability estimatesDefine expected progeny differencesDescribe the importance of livestock improvement
3 Overview Emphasis on certain traits depend on Economic importanceRate of improvement of specific traitFactors affecting the rate of improvementHeritabilitySelection differentialGeneration intervalExpressions of traits are influenced by genetics and environment
4 Genetics vs Environment Different factors affect growth in different waysHow can we tell the difference?Contemporary trials
5 HeritabilityAn estimate of the fraction of the phenotypic superiority or inferiorityEx: low heritability estimates ( ) % of variation is due to environmental factorsLow heritability traits change slowly
6 High vs Low Heritability High heritabilityReproductive traitsCarcass traitsFertilityFat thicknessCalving intervalRib eye areaLitter sizeEfficiency of gain** greatest effect on economic return!!** small effect on economic return!!
8 Expected Progeny Differences EPD – the expected (or predicted) difference in performance between the progeny of two animals of the same breed.Most accurate method of comparing breeding valueAccounts forIndividual’s, parent’s, sibling’s and progeny’s performance
9 Advantages of EPD’s Most accurate predictors of progeny performance Provide an accurate depiction of an individual/herd’s strength/weaknessAllow for greater specificity in multi-trait selection
10 Selection IndexPlace added emphasis on the more economically important traits
14 Visual Aids Ultrasound Technologies Done in real time Cross-section of rib eyeBack fat and REA
15 Objectives Compare and contrast the idea of genetics vs environment List examples of high and low heritability estimatesDefine expected progeny differencesDescribe the importance of livestock improvement