Reproduction: Applied Genetics Flashcards
What is quantitative genetics?
- Inheritance of quantitative traits- traits we measure
- Usually influenced by several genes at different loci
- Ecomomic intrest
What effects phenotype presentation?
Genetic and environmental differences
Vp = Vg + Ve
What is heritability?
Part of the phenotypic variation that is due to heritable gene effects
What are the highest heritability features?
- Body conformation
- Udder morphology
- Milk fat/protein
- Growth rate
- Milk yield
Less- BCS, BHBA
Repro low- not irrelevant
What are phenotypic correlations and genetic correlations?
Phenotypic
* Measure the direction and strength of association between observed performance/phenotypes
Genetic correlations:
* Direction and strength of association between genetic merit for two traits
What genetic correlations are of intrest in dairy cows?
- Milk fat, protein
- Mastitis
- Fertility
- BCS
- SCC
- BHBA
- Lameness
- Feed efficiency/DMI
- Green house emissions
- Immune response
- Bovine TB resistance
What are breeding values?
- Breeding value refers to the additive genetic merit of an animal
- Double the expected deviation in progeny performance from the populaitonmean
- Predicted from information including animals own performance/relatives performance
- Positive, negative or 0
How are breeding values predicted?
- Own performance records
- Parents performance records
- Progeny performance records
- Heritability of trait
- Comparisons between contemporary groups
- reliability of estimated breeding value
- Genomic estimated breeding values
What is bovine leucocyte adhesion deficiency?
- Single point mutation (adenine to guanine)
- Impaired expression of beta-2 integrin
- Fewer neutrophils get into tissue to fight infection
CS
* Ulcers on oral mucosa, gingivitis, chronic pneumonia recurrent/chronic diarrhoea
* Treatment- none
Autosomal recessive
What is CVM genetic disease?
- Complex vertebral malformation
- Autosomal recessive
- Mis-shapen and fused vertebrae around cervico-thoracic junction, symmetrical arrhrogryposis
- Bulls from major AI tested
What is holstein haplotype for cholesterol deficiency?
- Heterozygous animals have reduced cholestrol
- Homozygotes have no cholesterol
What are different conformation traits?
- Foot angle
- Legs parallel- not in/out
- Udder depth
- Teat placement- close/wide
- Rear udder width/height
- Udder support
- Fore udder attachment
- Teat length
- Rump angle
- Rump width
- Dairy form- skinny/fat
- Strength- chest width, body depth, bone quality
What are managment traits?
- Calving ease
- Life span
- Fertility index
- SSC
- Still birth
- Calf surivial
etc
How can genes be evaluated
Genomic evaluation
* SNP chop
* Better then averages
* Useful for natural mating
* Can be more reliable
