Principles of Selection Flashcards
(20 cards)
is the art and science of the genetic improvement of farm animals
Animal breeding
choosing some animals as parents of the next generation of animals
selection
removal of inferior animals
Culling
records deviated from a mean
Phenotypic deviation
is the proportion of the phenotypic variance that is due to genetic effects including additive, dominance and epistasis
Heritability in the broad sense
is the proportion of the phenotypic variance that is due to additive genetic effects only
Heritability in the narrow sense
animals are selected based on their ancestors, where the performance of these ancestors is known then a useful selection can often be made
Pedigree selection
the breeding value of each individual is assessed on the average performance of a random sample of its progeny, and animals are selected or culled based on this progeny performance
Progeny testing
any animals unsatisfactorily for the character being selected can be culled before breeding is commenced
Mass or Individual selection
selection based on the performance of nearby relatives
Family selection
selection is made for one trait or character at a time until it is improved, then for a second trait and so on
Tandem selection
a method where minimum standards of performance are established for each trait in the criteria. Any animal not satisfying the minimum standard for all traits is culled
Independent culling level
each character is given a score and scores for all characters being considered are added together. Those with the poorest total scores would be culled
Selection index
Mating between full sibs or between parents and progeny
Inbreeding
Mating of cousins, grandparent to grand offspring or half-brother to half sister
Linebreeding
Two different populations can be crossed with each other to produce an F1 generation which is used only for production purposes and not for breeding
Single two-way crosses
This system relies on the crossing of two breeds A and B to produce a female excelling in maternal performance in a particular environment and the use of a third breed to produced the ideal animal for the market product
Three-way cross
In which males of each of the two breeds involved are used alternately; this system has the advantages over the two-way cross, in that the crossbreed females can be used for breeding
Two-way rotational cross
In which males of each of the three breeds are used in turn; crossbred females produced can be used for breeding
Three-way cross
