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Animal Breeding Exam 1


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Systems approach
method used by breeders to try to attain "best" animal and sustain profitability.
observable or measurable characteristic of an animal
observed category or measured level of performance for a trait of an individual
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
variation in performance among different genotypes within different environments (or under different management practices)
there are degrees of difference in performance of genotypes with different environments
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

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
1. Selection
2. Mating
Breeding Value
the value of an animal as a genetic parent
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
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

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.
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
Most closely resembles expression of homozygous dominant genotype.

related to hybrid vigor

Dominance Misconceptions
-Dominant are Good while recessive are bad

-more common than recessive

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
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
the point at which a particular allele becomes the only allele at its locus
mating system
used to change gene and genotypic frequencies

increase frequency of homozygous genotypes and decreases heterzygotes
common ancestor
ancestor common to more than one individual
mating of unrelated individuals
hardy-weinberg equilibrium
if matings are made at random in a population, gene and genotype frequencies do not change

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