The proposal involves mapping the QTL affecting milk production and associated traits by selective DNA pooling. High resolution mapping will be carried out for some of the identified QTL, using selective recombinant genotyping within, and identical-by-descent mapping across the various populations. Allele frequency of QTL alleles, and marker haplotypes associated with positive and negative QTL alleles of active sires will be determined. Theoretical studies needed for use of QTL information for marker-assisted selection (MAS) will be carried out. The end product will be a body of QTL map information and sire marker/QTL information, and of validated methodologies for MAS for milk production traits in dairy and dual-purpose cattle.
The objectives of this project are:
1) to map QTL for milk yield and protein percentage in Holstein and Brown Swiss (dairy), Simmenthal (dual -purpose), and Red Holstein x Simmenthal advanced backcross
2) to determine the associated effects of the mapped QTL on protein yield, fat yield, percentage fat, milk somatic cell count, days open, calving difficulties and perinatal mortality
3) to achieve high resolution QTL mapping by selective recombinant genotyping, and by identical-by-descent mapping
4) to develop and test methods to estimate frequency of QTL allele in the population
5) to determine marker-QTL phase in active elite sires of the five populations
6) to trace marker-phased QTL to progeny
7) to develop a theoretical framework for incorporating marker-QTL map information in a realistic marker assisted selection (MAS) program
8) to develop a theoretical framework for evaluating the results of a MAS programme, and apply this to the five resource populations using the parameters obtained in this study.
Progress to Date
The most important benefits resulting from the first three years of this project are:
1) the organisation and implementation of a new logistic system for target sampling and pooling milk samples for genetic analysis using the existing recording system
2) additional sampling for fine mapping and tracing of QTLs
3) genome-wide genotyping of individuals and pools for both main traits
4) comparative mapping results as a platform for fine-mapping and identity by descent studies
5) initial results of intensive comparative study of six chosen QTLR
6) initial fine-mapping results for three QTLR
7) partially prepared samples and tool s for phase determination and QTL tracing
8) optimised new criterion for selective DNA pooling
9) reliable estimations of cost and returns of different MAS schemes.
Implementation of these actions improved and consolidated the contacts between project partners and beneficiaries of the results of this research project.
FOOD, ANIMALS, GENOMICS, QUANTITATIVE APPROACHES AND MODELLING
Scientist responsible for the project
||01 September 2001
||1 709 718 €
|Total EC contribution
||1 709 718 €