AbP final exam - semester 4

animal selection

breeding procedures in which the breeders chooses the parents for the futur generation

4 types of selection

* natural : free in nature, wild animals
* artificial : man - breeder
* mass : group of animal, eliminating undesirable genes
* individual: every animal is assessed ( appearance, pedigree, production)

breeding and selection goal

choose and breed animals with desirable traits

eleminate undesirable genes

degeneration + classification

higher in related individuals

outcome of domestication

\
lethal genes -- death during gravidity

semi lethal genes -- death of young animals

subvital genes-- lower vitality

\
morphological

physiological

psychological

variability of quantitative traits

* continuous variables : birth weight, amount of milk production
* discontinous variables : number of eggs, piglets per litter

quantitative inheritance

involve individual less and population more

quantitative traits characterisitic

* influenced by many pair of genes
* P=G+E --- G = Additive gene action + Dominance gene action + Epistasis gene action

population genetic

* study of genetic variation among a population

\

polygenic trait

group of genes that when expressed together gives a particular phenotype

== controlled by two or more genes

arithmetic mean importance -- calculation

* phenotypic value of the traits
* number of individual in population

Aim of selection

improve average value in the population ( selection of parents above average)

why do we use statistical evaluation of quantitative trait

* offspring who carries desirable properties
* with which certainty some traits will be transferred( heredity)

Heritability (h²)

* strength of inheritance of a character ( likely or not to be transferred)
* based on how much relatives resemble each others
* concerned with differences between inidivuals or group of individuals == not absolute values
* value between 0 and 1 ( 0= no genetic variability)

\
* can be used in a
* narrow sense : includes only A ( additive types of gene action) or average effect of each gene in population
* broad sense : all of the effect of the heredity for each individual + addition of variation due to additive gene ( dominance…)

\

Additive gene action

* **phenotypic of one gene add to another**
* traits of economic importance
* when traits are **highly heritable** + little to no heterosis or inbreeding
* important to standardize the environment to avoid P variations
* select the best and mate it with the best

Dominance gene action

* usually desirable traits
* heterozygous = superior to homozygous ( superior in vigor of performance)
* --- important to identify heterozygous individuals to eliminate recessive gene

Epistatic gene action

* interaction between genes that are not alleles

\

high h² estimates

large portion of phenotype is connected with genotype

low h² estimates

* often
* selection procedures according to phenotype is not reccomended
* -- low correlation btwn phenotype and genotype
* -- low variation due to Additive gene action
* -- high importance of dominance and epistasis genes
* == important to look at the performance of the relatives and progeny
* not a static value ( varies)

H² estimates is determined

ressemblre btwn

1- siblings

2- half sibling

3- parents and offspring

\
* useful in gain tests

repeatability estimates

* expression of the same trait at a different time in the life -- likelyhood of repeatability
* fraction of differences between single records
* heritability and repeatibility are related to superiority and inferiority of animals

Criteria for selection

* mean = starting point ( and then + or - depending on trait)
* number of individual necessary to get replaced

\

selection differential

* how good the parents chosen will be == superiority of selected parents in comparison to the mean
* SD = Xs- X (mean of the parents- overall mean)
* indicator of efficiency in selection
* the more the number of selected trait, the smaller the selection differential for each individuals traits

selection intensity

is= SD/ Phenotypic standard deviation

\
Phenotypic standard deviation = if the variation is normally find in the trait of a population

generation interval

* time interval between generations ( average age of parents when offspring is born)
* limited by puberty
* \

reasons for replacement

* renewal rate-- number per year
* replacement rate = Renewal rate / **average** number of **offsrping** of the same **sex** per animal per **year**

Positive effect of crosses

* hybrid ( heterozygote)
* heterosis ( positive hybrid vigor)-- better than the mean of the parents
* heterosis=(Mean F1 offspring -mean of parents)/ Mean of parental breeds x100

prediction amount of progress through selection

* Gain per generation= heritability x selection differential

Polymorphic genes

many genes are polymorphic - different forms

degree of which selection affect a trait depends on (4)

* heritability
* variability
* intensity of selection
* generation interval

factors to consider when selecting a breeding stock

* age -- younger animals ( longer productive life)
* lvl of performance -- highest prdction level ( high milk, woo,egg prdction)
* physical fitness -- free from any physical defect, not sick
* body conformation -- according to production type
* temperature and behaviour -- bad behaviour-- culled
* quality of product -- high quality ( meat, milk, egg…°
* Mothering ability --
* adaptability (climatic condition)
* prolificacy -- highly prolific

breeding value

* **economic worth of an animal genotype**

\-- judged by ability of offspring
* for qualitative and quantitative traits

== genetic merit

* measured with Estimate breeding value
* performance of animal is compared to the other individual in the group
* advantages : makes it possible to avoid extreme values for particular traits

Method of estimation for BV

* pedigree -- **performance of ancestor**
* performance test ( individual or mass selection) -- **animal phenotype**
* performance of relatives -- **relatives phenotype**
* progeny testin -- **phenotype of progeny**
* BLUP method ( combination of data)
* **genetic test**

estimation according to ancestors

* if ancestor also have traits of quality it is more likely that they will transfer it to their offspring
* pedigree ( 3 generations)
* depends on h²

\

Estimation according to production records

* exterior ( breed strandards)
* primary and secondary sexual characterisitics
* health

\
* linear scoring
* measuring and grading
* body score
* performance test (field test)
* depends on type and sex
* measured on animal ( fattening charac…)
* BV= h²\*(Px-A)
* A= population average
* Px= phenotype of the individual
* reapitability ( accuracy)

\

Estimation according to performance of relatives

* for low h²
* **Sib test**
* often for pigs breeding

Estimation according to the progeny

* progeny testing
* when low h² or only in one sex
* the greater the number of offspring the more accurate it will be

\
* factors for successful progeny testing: - random selection
* offspring are in production the same year and same season
* environmental factors should be as equal as possible

\

BLUP ( best linear unbiased prediction) method

* most accurate
* goal : to improve a higher number of properties simultaneously


* advatanges : - BV assessment btwn farms
* performance form pedigrees
* large amount of information = accurate

Genetic selection

* genomic selection

pig breeding program

* pyramid organization
* nucleus herd
* multiplying herd
* production ( commercial herd)
* market pigs

Field test

* **Animal testing in production condition**
* implementation of testing
* measurement of properties
* data records

== improvement of pig production by BLUP method

\
* selection procedure :
* litter selection
* selection after weighing
* data entry
* data calculation

Cattle breeding

* milk production :
* milk control : measuring and sampling
* results are including in breedin program
* meat production :
* BV are calculated for the net daily gain
* fitness
* natural mating
* pregnancy
* prenatal death
* exterior
* description and evaluation

\

genetic BV estimation cattle

* MMM= mixed model methodology
* BLUP results
* MM= sires and cows are simultaneously evaluated using genetic linkage
* data included :
* ease of calving
* fertility charac
* quality of meat
* exterior
* milk production testing
* Total merit index

Targeted mating

* selection of top bull’s sire and bull’s dam

\
* top dams :
* elite cow
* production properties surpasse population for 2 SD
* inlcuded in MOET
* top sire :
* positive test values

sheep breeding improvment

* control of milk production
* performance test in fields condition

sheep estimation of breeding value ( what’s taken into account)

* lambing season
* lactation stage
* lamb weight
* litter size
* Additive genetic action on lamb

improvment of goat breeding and selection

* reproductive traits
* milk production
* performance test (field conditions)

Horse breeding selection criteria

* pedigree
* external appearance
* health
* performance test
* colour
* progeny performance

Poultry breeding

* age
* fertility
* eggs charac ( size, number, colour…)
* feather colour

dog and cats breeding important traits

* appearance
* behvaiour

biotechnology definition

technological application that uses biological system, living organism to make or modify products

biotech i livestock production

* biological
* chemical
* physical techniques that influence animal health, nutrition, breeding and reproduction

biotech animal health

* vaccine production === primary
* vector control
* quarantine
* === secondary
* advances: - detection of nucleic a, proteins and specific antibodies
* futur : genome sequencing data ( for vaccins)-- heat stable vaccins ( no need for refrigiration)
* important area in developping countries -- high disease challenge

biotech in ABP

* maintaining **genetic biodiversity**
* increasing **breeding efficiency** and livestock
* within organized breeding scheme
* conservation of animal genetic
* criterias taken account: - growth rate and litter size
* genetic gain -- thanks to **Artificial insemination** and embryo transfer -- new : cloning, transgenic animal

Artificial insemination -- biotech reproduction

* genetic progress 4 times better than natural mating
* use of superior sires = most effective tool
* mainly for dairy cattle

Embryo transfer

* function : increase reproductivity rate of valuable females
* in cattle
* in highly commercialized livestock production
* MOET ( multiple ovulation and embryo transfer technique) -- increase the utilization of superior dam ( increase intensity of selection) -- use of PMSG and FSH
* recepient cow must be in estrus within 1.5 days of the donor’s result

Genetic markers

genes or DNA that have a known location and are easily identifable

ex: causative mutation

MAS -- marker assisted selection

phenotype selection method

use of genetic map

difficult in developing countries

breeding scheme

* offer opportunity for use of biotech
*

transgenic animal def

* animal which carry foreign dna in genome
* why ? :
* to improve milk production
* increase disease resistance
* improve feed efficiency
* increase growth rate


* high cost limited success

farm animal cloning

* might be useful for : - preservation of elite male and female
* modify genes