Genetics and Horse Breeding Flashcards
what is selection
- causing or permitting some individuals to produce more offspring then others
- human-directed selecting, human selection does the same thing but in with different goals
factors in selection
- breed or dont breed = when you breed there should be a reason
- how many offspring
No thoroughbred can be registered without natural conception, why?
- stops inbreeding (partially)
- keeps the stud feed high
what are focal traits
-performance
- conformation
- temperament
- trainability
- genetically clean
what type of traits are most selective criterias
- quantitative traits
- measured on a continous scale
- polygenic
- phenotypic is function of genetics and environment
what are examples of quantitative traits
- conformation
- performance
- longevity
- fertility
- height
- weight
- angle of pelvis
- cow sense
- quality of trot
jumping ability - environment = management, trainer, rider
what happens with variance
- if theres two little phenotypic selection - not a lot to choose
if the phenotype is similar the genotype is likely too similar
what creates phenotypic variance
genotypic variance + environmental variance
what is the purpose of selection
- direct change in some characteristic(s) of the population which exhibit genetic and phenotypic variation
what is the effect of selection
- change in frequency of allele (s) that influence trait(s) being selection
- traits may be selected directly or indirectly
what happens during selection success
- imporvement (change) in trait (s) for population
- changes the mean
- reduces the variance
what determines a response in selection
depends on heritability and selection intensity
rate also depends on generational interval
- proportion of difference between animals due to differences in genotypes
what is considered good heritability
- environment are identical h2=1.0
- if all animals are clones h2=0.0
- measure of how much of differences between animals are due or not due to genetic differences
what is taken into consideration for breeding stock selection
- heritability
- generation interval
- selection intensity
what are other breeding stock selections considerations
- indirect selection effects
- inbreeding
