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21 Cards in this Set
- Front
- Back
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Gene:
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active area on chromosome that codes for a trait and determine how that trait will develop
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Alleles:
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alternate forms of a gene
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Homozygous:
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like alleles “BB or bb”
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Heterozygous:
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unlike alleles “Bb”
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Genotype:
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genetic makeup
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Phenotype:
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the expressed characteristics
Combination of genotype and environment |
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Qualitative traits
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•Primarily determined by genotype
•Little or no environmental influence •Determined/ controlled by a small number of genes •Detected by visual observation •EX: hair color, horns |
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Quantitative Traits
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•Most traits of economic importance
•Show continuous variation oCannot be separated into distinct groups •Affected by many genes oImpossible to determine effect of one gene pair •Environment affects gene expression |
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Selection
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•Important tool for genetic improvement
•Differential reproduction •Change in gene frequency in the population o Increase frequency of desirable genes o Decrease frequency of undesirable genes |
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heritability
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•% of phenotypic variation that is genetic and transmitted from parents to progeny
•Ranges from 0 to 100% •It is an estimate |
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What trait has the lowest heritability? the highest?
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reproduction; mature size/carcass traits
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Expected Progeny Difference:
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The amount by which the average progeny of the animal is expected to exceed the average of the herd population
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What is EPD used for?
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•Best tool for genetic selection
•Used to compare genetic potential •Available for cattle, sheep, and swine •Theoretical average = 0 |
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Straight breeding:
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mating animals of the same breed
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Crossbreeding:
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mating animals of different breeds
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Composites:
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oResults from the combining of desirable traits of various breeds
oGet good w/ the bad oTerm used in cattle, sheep, poultry |
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Hybrids:
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(used in swine industry)
oDeveloped from specific line crosses, selected for a specific trait oLarge corporate seedstock suppliers of boars and gilts |
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What is a breed?
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•Animals of common origin
oPossess characteristics that distinguish them from other groups within the species oThrough selection and breeding, come to resemble and pass traits uniformly to offspring |
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Breed complementation:
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match strengths and weaknesses of different breeds
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Heterosis(hybrid vigor):
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increase in productivity of the crossbred progeny that is greater than expected based on the average of the parents
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% heterosis:
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difference/ amt expected
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