Population Genetics Farm
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How does the modern dairy cow differ to an old style of cow?
^ milk yield v fertility v health v utility or robustness
How do quantitative genetic traits differ from qualittiative?
Can be measured, but often based on 1000s of genes which are usually NOT KNOWN - select based on phenotypic trait not distinct bit of DNA
Give 3 types of dairy system
• ^ input/output • pasture based • niche markets eg. organic, soil association guidelines etc
What is a selection index?
Multiple traits combined and weighted for importance and interaction between them eg. productivity index = milk yield, fertility etc. • often given in terms of monetary value • may incoroporate welfare, temperament etc
What are EBVs called in the dairy industry?
PTA (predicted transmitting ability)
What are the majority of dairy cows nnowadays?
> 90% holstein only 10% fresian (black and whites)
What is PIN?
Production index = kg milk, milk fat, protein
How is fertility measured in the dairy industry?
Calving interval
What is £PLI?
Profitable Lifetime Index - milk PTA \+ fat PTA \+ protein PTA \+ lifespan PTA - SCC PTA \+ locomotion PTA > each will have an associated value, so 1 unit ^ characteristic affects £PLI by x amount
How does SCC PTA affect the merit of a bulls £PLI?
negative is good! • 15% = decrease daughters SCC by 15% • SCC good predictor of mastitis
How are production, health and fertility traits linked? How does this impact bull choice?
• milk, fat, protein ^ mastitis • milk, fat, protein ^ lameness • milk, protein ^ fertility CI • fat ^ fertility CI > want a bull that breaks these correlations as all are negative!! > selction index identifies bulls that go against these correlations eg. those with ^ milk yield but v calving interval
How is a fertility index formulated?
Combine a fertility trait PTA (or multiple traits) with relative economic value eg. FI = -0.31(CI) +1.56(Non-return rate) to give an economic approach to choosing bulls
How has the £PLI recently been improved?
Broaden the breeding goal - include fertility, revision of economic values [dairyCo], condition score and environmental sensitivity [Robust cows]
What outputs are aimed for in the future dairy cow?
Milk of the right composition and produced the right way (consumer driven) Less calves and less cull cows Imprived welfare and environmental impact ^ profits
Why is genetic improvement particularly viable in the dairy industry?
AI
Give examples of the traits scored for holstein classification process
stature rump width, angle udder milk foot angle chest width temprament