Genetics and Animal breeding deck 2 Flashcards
In horses gestation lasts for approximately
approximately 340 days
in cattle gestation lasts for approximately
280 days
in sheep gestation lasts for approximately
150 days
in swine gestation lasts for approximately
about 114 days
3-3-3 rule
3 months, 3 weeks, 3 days
The length of incubation of a chicken egg
21 days
Embryogenesis lasts for in cattle
5 weeks
Embryogenesis lasts for in sheep
4 weeks
in swine Embryogenesis lasts for
3 weeks
Define embryogenesis
this period is characterized by intensive differentiation of cells and the development of primitive organs
this stage comes after conception
Define organogenesis
stage of gestation for rapid development and extensive relative growth, whereas the absolute growth remains small.
basis for organs and associated systems are formed in addition to cartilaginous skeleton and nervous system
Define the prenatal period
the longest stage of gestation after organogenesis-stage and lasts till the birth.
32 weeks in cattle,
5 in sheep and
11 in swine.
Define absolute growth
is the increase in body mass or size in a given time period
measured by weighing
Define relative growth
describes growth intensity
Shows the ratio between absolute growth (A) and the initial mass, given in percent.
absolute growth is denoted?
A
relative growth is denoted?
K and in percentage
What is the regression coefficient
(b) describes the relationship between traits Y and X
how is regression coefficient denoted
b (y/x)
how is regression coefficient calculated
is calculated in two ways: regression of trait Y on trait X, or regression of trait X on trait Y.
e.g. between body weight as y, and age as x
how many units the value (y) of trait Y will change if the value (x) of trait X will change by one unit.
b = (y kg / x days)
Define biocoenosis.
An association of populations living together in a habitat is called a biocoenosis.
define open population
Individuals of an open population may mate with individuals of other populations that have a significantly different genotype.
define population size
is defined as the number of individuals present in a population.
A random sample is what
is a sample of a population that is chosen randomly without bias. Processes that are non-predetermined under certain circumstances. It is stochastic.
What is the probability of an event?
The expected frequency of the event A is called the probability of the event that is written p(A).
What does genotype frequency indicate?
Genotype frequency indicates the genetic structure of a population and the prevalence or number of different genotypes in the population.
What does gene or allele frequency indicate?
The frequency or prevalence of the different genes/alleles existing in the different genotypes of a population. Allele frequency can always be calculated from genotype frequency.
What conditions must a population meet for Hardy-Weinberg’s law to apply?
1) individuals mate randomly
2) individuals with all genotypes are of identical fertility
3) there is no selection
4) no mutations
5) there is no gene flow between populations
6) there is no gene drift
7) the number of individuals in a population is infinitely large
Emigration refers to?
individuals removed from a population.
Immigration refers to?
new individuals being introduced into an open population.
The impact of migration (in or out) on the genetic balance of the population…?
may change the gene and genotype frequencies of the initial population.
The impact of migration (in or out) on the genetic balance of the population…?
may change the gene and genotype frequencies of the initial population.
What is the formula for calculating effective population size.
Ne = (4N♂• N♀) : ( N♂+ N♀)
the probability of the event can be written as the formula..?
0 < p (A) < 1
What does inbreeding coefficient (Fx) tell you
measures the proportion of the loci which was heterozygous in the base population, which probably has become homozygous due to inbreeding.
what is passive inbreeding
Inbreeding may occur in a small population where a very small number of animals increases the opportunity for loci in the offspring to become homozygous.
define outbreeding
Outbreeding is a general term applied to any breeding system in which animals mated are less closely related than the average of population from which they come.
What does the phenotypic value of an individual depend on?
is due to its genotype or genotypic value (Gi) in conjunction with environmental factors (E).
Correlation coefficient demonstrates
the degree to which a trait changes, if the other trait either increases or decreases.
what is rP
Phenotypic correlation (rP)
correlation coefficient which is calculated between phenotypic traits
what is rG
Genetic correlation (rG)
correlation coefficient which is calculated between phenotypic traits of RELATIVES (not to be confused with rP)
correlation coefficient range is?
from -1 to +1
what is regression analysis
involves identifying the change in the numerical value of one trait if the numerical value of the other trait will change by one unit.
Which traits are taken into account in estimation of breeding value of animals?
Performance data (e.g. milk yield) Exterior traits Growth and development rate Fertility Health
Sources of information for the estimation of breeding value.
based on the data of the animal itself and the relatives
Multiple sources of information increases the accuracy of breeding value estimation.
What is a fixed reference base in reference to breeding values
using the BLUP method to compile data for reference.
what is absolute breeding value (BV)
is the breeding value that has been calculated based on the fixed reference base (BLUP)
What is a moving reference base
a reference baseline that is constantly updated to suit modern data
made from one or several successive contemporary groups of individuals (bulls) all of whom have received their first relevant value estimates.
what is (RBV)
relative breeding value for an individual is calculated based on the average breeding values of the reference bulls and the standard deviation from those values
Which organization deals with the international evaluation of bulls?
An organization called INTERBULL, located in Uppsala, Sweden. Internationally carries out genetic evaluation of dairy bulls
Concept of selection:
Selection is a process of deciding which animals are allowed to become parents of the next generation, and which ones with undesired properties will be culled.