final exam review Flashcards
if a strong negative change in mature weight is observed along with a strong positive change in meat tenderness then the two traits have a…
strong, negative correlation
what is considered the most important genetic parameter for an individual?
breeding value
the degree of heterosis in the offspring can be affected by…
- the repeatability value of the traits
- the type of gene action that the trait is under
correlation…
- the correlation of X and Y is the same as the correlation of Y and X
- correlation is unitless
- it only ranges from -1 to 1
in a non-random mating…
- expected proportion of homozygous and heterozygous individual deviates from H-W
- assignment of mate can be based on genetic relationship and phenotypic similarity
inbreeding depression…
- the opposite of heterosis
- results from poor gene combination value
bxy
- is the regression of Y on X
- variation in trait X influences the variation in trait Y
- there is an assumption of cause and effect
effects of outbreeding will include…
- increase in heterozygosity
examples of a major or extensive use of crossbreeding
- commercial cow/calf beef operation
- crossing of inbred lines to maximize production and growth in swine
- crossing of white cornish X white plymouth rock in poultry
not: crossing of two dairy breeds such as holstein and jersey
environmental correlation
- measure of strength of relationship between environmental effects of one trait and another
- they are often used for management purposes
heterosis
- results from increased heterozygosity
- gene combinations are not transmitted to the progeny
assume the average birth weight in a population is 75 lbs, the average weaning weight in a population is 400 lbs, and the phenotypic regression of weaning weight is 2.75 lb per lb. If a calf’s birth weight is 77 lbs, then what is the estimated weaning weight for this calf?
405.5 lbs
the measure of strength between BV for one trait and BV for another trait
genetic correlation
the measure of how well two breeds compliment each other for a specific trait
specific combining ability
a mating system where the best male for a trait is mated to the best female for that same trait
positive assortative mating
animals with the same alleles from a common ancestor are said to be…
identical by descent
a system of mating where genes of a common ancestor is concentrated in an individual
linebreeding
matching purebred males to non-purebred females in an attempt to create a purebred population
top crossing
combining the desirable characteristic of 2 or more breed (or lines) into the same offspring
breed complementation
animal model which combine all information known about an individual and its relative to create a genetic profile of the animal’s merit used mainly in meat producing animals
expected progeny difference
expectation of a squared deviation from its mean
variance
the superiority of the offspring from out red mating in comparison to the average phenotypic merit of offspring from purebred mating contributing to the cross
hybrid vigor
term used for alleles in individuals that happen to look alike but not traceable to a common ancestor
identical by state
the ability of the parent to impress its hereditary characteristics on its progeny because of increased homozygosity
prepotency
the probability that two alleles at a locus in an individual are identical by descent
inbreeding coefficient
rate of genetic change with selection will depend on:
- selection differential
- generation interval
- heritability
accuracy of an individual performance:
- based on individual record
- the higher the heritability, the greater the accuracy
- accuracy us equal to square root of heritability
pedigree information is one of the valuable sources for information for taking selection decision because:
- it is valuable for traits expressed later in life
- it is cheap
- it is valuable for sex-limited traits
the major objective for progeny testing for a qualitative trait:
to help determine the likelihood that an animal is a carrier of a detrimental recessive allele
independent culling method
- animal must meet standard for each trait in order to be saved for breeding purposes
- it has a potential of culling animal that is outstanding in one trait
BLUP
- method of genetic selection appropriate when performance data came from genetically diverse groups
- is an extension of selection index
- simultaneous solution of number of equation using matrix algebra
across breed EPD adjustments
- useful to commercial producers purchasing bulls for use in crossbreeding program
- accuracy of across breed EPD depends on accuracy of within-breed EPD for the bull
- useful in estimating divergence of birth weight EPD for bulls to breed to first calf heifers
in equine selection, some of the problems in determining heritability includes:
- tremendous environmental variation
- data bias
- limited information which results from analyzing the best
in dairy selection program, selection is primarily based on sire because:
- sire produces more progeny than dams
- AI allows for even larger number of progenies
- lower cost associated with keeping few or no bull at all
beef infrastructure includes the following:
- purebred
- cow/calf
- stocker
average age of parents when the animals that will replace them in the flock or herd are born
generation interval
a selection method that selects for a single trait at a given time
tandem selection