2. Introduction
In developed countries animal breeding is based on
quantitative genetics
Nicolas,(1996)
Quantitative genetics is multifactorial, influenced both by
gene and environmental factors and their interaction
(Beuzen et al., 2000)
Improvement of livestock focuses on the selective breeding
of individuals with superior phenotypes
Williams,(2005)
MAS is a powerful tool in animal breeding, improves the whole
range of desirable traits
7. Molecular markers
Molecular marker are specific fragments of DNA that can be
identified within the whole genome
They are used to 'flag' the position of a particular gene
Molecular markers are used in molecular biology to identify a
particular sequence of DNA
(Chauhan and Rajiv, 2010)
8. Features of Molecular Markers
Characteristics:
Co-dominant expression
Early onset of phenotypic
expression
High polymorphism
Random distribution throughout
the genome
Assay can be automated
9. Classes of Molecular Markers
Hybridization- based DNA markers
RFLP, oligonucleotide fingerprinting
PCR based DNA markers
RAPD, AFLP, SSR
Sequencing based DNA markers and DNA Chip
SNP
Vogel et al.,(1998)
10. Restriction Fragment Length Polymorphism (RFLP)
Principles
RFLP analysis is a standard, well-tested procedure for estimation
of genetic diversity
Tanksley, (1993)
RFLP analysis is based on the ability of restriction enzymes to
cleave DNA at specific target nucleotide sequences
Fairbanks, (1995)
11.
12.
13. • Simple sequence repeats are present in the genomes of all
eukaryotes and consists of several to over a hundred repeats
of a 1-4 nucleotide motif.
14.
15.
16.
17. SNP
• The most common genetic
polymorphism
• Distribute throughout
genome with high density
• More stable and easy to
assay
• Facilitates large scale
genetic association studies
as genetic markers.
20. The process of using the results of DNA-marker
testing to predict the genetic merit of the
animal being tested and assist in the selection
of individuals to become parents in the next
generation.
21. • Marker assisted selection (MAS) is an indirect
selection process where a trait of interest is selected
not based on the outward appearance of the trait
itself but on a genetic marker near the trait (gene)
on the DNA.
22. • MAS - Use of information from genetic markers to
help make selection decisions of animals for
genetic Improvement.
• This is done in a manner that exploits both known
major genes and all unknown genes.
29. Potential benefits from MAS are
greatest for traits that
Have low heritability
Are difficult or expensive to measure (disease resistance)
Are currently not selected for as they are not routinely measured
(tenderness)
30. •Time consuming
•Difficult
MAS Vs. PS
•Costly
•Performed off season
•Gene pyramiding
•Early stages of development
•Several selections simultaneously
•Low heritability traits
31. MAS in selection programming
BETWEEN
BREED
SELECTION
WITHIN
BREED
SELECTION
INTROGRESSION
IMPROVEMENT OF SYNTHETIC LINES
34. Low impact of MAS
Resources not available
Markers may not be cost-effective
QTL mapping
QTL effects may depend on genetic background
or be influenced by environmental conditions
Poor integration of molecular genetic and
conventional breeding
