Animal Breeding Exam 1
Terms
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- Systems approach
- method used by breeders to try to attain "best" animal and sustain profitability.
- Trait
- observable or measurable characteristic of an animal
- Phenotype
- observed category or measured level of performance for a trait of an individual
- Genotype
- genetic makeup
- Phenotype =?
- Genetic + Environment
- Best animal components?
-
1. Traits of primary importance
2. Phenotypes and genotypes most desirable for those traits - Systems approach = components?
-
1. animals
2. physical environment
3. fixed resources
4. management
5. economics - Genotype x Environment Interaction
- dependant relationship between genotypes and the environments.
- Breeding objective
- the general goal of a breeding program; typically in-line with notion of what is the best animal
- dependent
- variation in performance among different genotypes within different environments (or under different management practices)
- relative
- there are degrees of difference in performance of genotypes with different environments
- Breeds
- race of animals within a species that are often genetically adapted to different conditions
- Elite Breeders
-
Top selling breeding stock
Define best animal for end usuers
seedstock producers
historically purebred breeders
- Multipliers
-
large #'s, selling breeding stock to end users
Multiply elite breeders animals for end users - End users
-
largest numbers
final users of breeding stock
utilize genetics on a larger scale
- Commercial Producer
- animal breeder whose primary product is a commodity for public consumption
- Germ Plasm
- Genetic material in the form of live animals, semen, or embryos
- Factors that distort breeding objectives
-
Satisfying expectations that have little to do with the end user
competition among breeders and the need to be perceived as having superior animals - Intermediate Optimum
- an intermediate level of performance that is optimal in terms of profitability and or function
- Tools to improve genetics
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1. Selection
2. Mating - Breeding Value
- the value of an animal as a genetic parent
- Heritability
- a measure of the strength of the relationship between phenotypic values and breeding values for a trait in a population
- Performance testing
- the systematic measurement of performance (phenotype) in a population
- Pedigree Data
- genotype or performance of ancestors and or collateral relatives of an individual
- Progeny dataa
- genotype or performance of descendants
- Accuracy
-
measure of the strength of the relationship between true values and their predictions
- genetic prediction
- area of academic animal breeding concerned with measurements of data statistical procedures and comp techniques for predicting breeding values
- Hybrid vigor
- increase in performance of hybrids over purebreds, most noticeably in economically importnant traits
- inbreeding depression
- a decrease in the performance of inbreds
- Seedstock producers
- no concerned with heterosis or breed complimentarity. practice mild inbreeding to maintain genetics
- commercial producers
-
produce crossbred animals
- gene
- basic unit of heredity consisting of dna sequence at specificlocation on chromosome
- Medel's 1st Law - Segregation
- seperation of paired genes during germ cell formation so that only one gene is incorporated into the germ cell
- mendel's 2nd law - independent assortment
- independent segregation of genes at different loci.
- Dominance
- interaction between genes at a single locus. One allele has more effect than the other
- Complete Dominance
- expression of Aa = AA
- Partial dominance
-
HH is most severe
NH still shows symptoms - No dominance
- heterozygote = 1/2 between homozygous genotypes
- Overdominance
-
Most closely resembles expression of homozygous dominant genotype.
related to hybrid vigor - Dominance Misconceptions
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-Dominant are Good while recessive are bad
-more common than recessive - Epitasis
- interaction among genes at different loci such that the expression of genes at one locus depends on the alleles at one or more other loci
- Breed true
-
phenotype for a simply inherited trait is said to breed true if parents with that phenotype produce offspring of that phenotype exclusively
-Only yellow labs breed true - Sex linked inheritance
- pattern of inheritance for genes located on sex chromosomess
- hemizygous
- having only on gene of a pair
- sex limited inheritance
- a pattern of inheritence in which phenotypic expression is limited to one sex
- sex influenced inheritance
- a pattern of inheritance in which modes of gene expression differ between males and females
- population genetics
- study of factors affecting gene and genotypic frequencies in a population
- fixation
- the point at which a particular allele becomes the only allele at its locus
- mating system
-
used to change gene and genotypic frequencies
- inbreeding
- increase frequency of homozygous genotypes and decreases heterzygotes
- common ancestor
- ancestor common to more than one individual
- outbreeding
- mating of unrelated individuals
- hardy-weinberg equilibrium
- if matings are made at random in a population, gene and genotype frequencies do not change