Ch. 2 Flashcards
The purpose of animal breeding
to genetically improve populations of animals
tools used by animal breeders
selection and mating
Mating*
the process that determines which selected males are bred to which selected females
Two types of selection
natural and artificial
Natural selection
evolutionary force and survival of the fittest
artificial selection
Has human control by replacement selection and culling
Replacement selection
young animals, replacing older animals. (involved A.I. and E.T.)
Culling
25-30% yearly cull rate recommended for livestock
goal of selection
individuals w/the best set of genes reproduce so the next generation (on avg.) has more desirable traits than the previous generation. Individuals w/ the best set of genes have the best breeding value
Heritability
a measure of the strength of the relationship between breeding values and phenotypic values for a trait in a population
Performance testing *
systematic measurement of performance in a population. It varies among species and breeders in a species. Usually seedstock producers participate
Dairy Herd Improvement Association (DHIA)
Established in 1965 it collects and processes info on dairy cows for 1/3 of the US producers.
Pedigree Data *
info on the genotype or performance of ancestors and/or collateral relatives of an individual
Progeny data *
info on the genotype or performance of descendants of an individual. Can also be used to predict breeding values.
A pedigree contains
performance data and genetic predictions
Accuracy*
a measure of the strength of the relationship between true vales and their predictions (also called repeatability or reliability)
genetic predictions*
the area of animal breeding concerned with measurement of data, statistical procedures, and computational techniques for predicting breeding values and related values.
sire summaries*
a list of genetic predictions, accuracy values, and other useful info about sires in a breed
Polygenic traits*
traits that are affected by many genes w/no known single [major] gene having an overriding influence
Simply-inherited trait*
a trait affected by only a few genes
between-breed selection*
the process that determines the breed(s) from which parents are selected
Complementarity*
An improvement in the overall performance of offspring resulting from mating individuals w/ different but complementary breeding values
crossbreeding*
the mating of sires of one breed or breed combination to dams of another breed or breed combination.
Hybrid Vigor or Heterosis*
an increse in the performance of hybrids over that of purebreds.
what are the most common improvements?
fertility and survivability
Inbreeding*
The mating of relatives
Inbreeding Depression*
A decrease in the performance of inbreds, most noticeably in traits like fertility and survivability
Line breeding
Careful inbreeding within lines can be useful to produce heterosis when crossing w/other lines (outbreeding)
Corrective mating*
A mating designed to correct in their progeny faults of one or both parents
