Matt Spangler
Beef Genetics Specialist
University of Nebraska-Lincoln
Few markers and seemingly easy to interpret resultsStars—Not all stars are equal
The number of markers has grownEvolution of 50k
Results have changedMolecular Breeding Values (MBVs)Some have a metric of accuracy
MBV is not equal to an EPDCurrent accuracy metrics not equal to BIF
accuracy
Advertising for seedstockX star bull for trait y10 bull for tenderness
Selection decisionsLimited--Confusion
Results were not appropriate for educated selection decisionsNot included in NCE
Disjoined sources of informationGood test result and poor EPD
• Bull on the left has the most desirable genetic test Bull on the left has the most desirable genetic test valuevalue
• Bull on the right has the least desirable genetic test Bull on the right has the least desirable genetic test value but favorable EPDvalue but favorable EPD
• Bull on the left could be undesirable for an infinite Bull on the left could be undesirable for an infinite number of other markers while the bull on the right number of other markers while the bull on the right could be desirable for an infinite number of unknown could be desirable for an infinite number of unknown markersmarkers
Marker panels have grownFormat of results has changed
MBVsInclusion in NCE is happening
AngusNovel traits are being collected
HealthHealthfulness
Multiple companiesMultiple panels
Differing sizesDiffering traits
50k is getting a big brotherMinimal inclusion into NCE
Who to test and with what panelShould I test
Ultrasound vs maker panelInformation flow—HowWhere will training of panels occur
US MARC must play a key roleEnough cattle?
Economically there is benefit to only testing some animalsWGS not currently feasible for wide-spread useReduced panels more logical for non-AI sires
Most influential?i.e. large diagonal element of A-1
Novel search algorithms to eliminate testing of multiple sibs
Those who might be influential in the future?Prior knowledge of parents diagonal element
and other metrics
Closer the target population is to the training population the better they will work
If robust diagnostics are the goal then non-informative SNPs are a concern (IBD)i.e. using an Angus panel to predict in
Charolais
Fitting a single causative mutationFitting Marker Scores and Genomic
RelationshipsMarker scores represent additional phenotypes
correlated to the trait of interestGenomic relationships represent realized
relationship as opposed to expected relationships
Increased accuracy of predictionEarlier selectionIncreased array of traits
Why the low correlations (accuracy) for yearling bulls?
Uncertainty surrounding what alleles were received from parents
We begin to understand this when an animal has a record
Becomes more clear as we see what it is passing on to its offspring
Commercial producers do not have this luxury
Pedigree estimatePedigree estimate + individual record (if
available)Full pedigree + individual record (if available)Full pedigree + individual record (if available)
+ progeny records
Take Home: Collection can take a long time. Records of relatives benefit an individual.
Pedigree estimate+ Molecular ScoreMore information earlier=higher accuracy
earlierInsight into Mendelian sampling
Take Home: Information is available earlier.
Rate of genetic change is determined by:Accuracy, genetic variation, selection intensity,
and length of the generation intervalGeneration interval is approximately 6 yearsMore young sires as parents?
Two yearling bulls with a +40 weaning weight EPDOne low accuracy and one high accuracy
Are they really the same?
10 20 30 40 50 60 70
Difference in EPD AccuracyAcc = 0.30, Possible Change = 8.1Acc = 0.8, Possible Change = 2.3
Two yearling bulls with a +5 CED EPD with accuracy of 0.2.Possible change of 6
With the addition of more information their EPDs change
One favorably and the other unfavorablyMore information earlier allows you to choose
animals more accurately
Bull A Bull B+5 +5
Add molecular scores as additional information
Bull A Bull B-1 +11
In this extreme case risk was 10% more calving difficulties
Average is still +5*
Lowly heritableHard or expensive to measureMeasured late in lifeSex specific
Producers (seedstock and commercial)Researchers (university and USDA)DNA companiesBreed AssociationsOutreach
“Marker Panel” “Correlated Trait”Value of the molecular score depends on:
Validation results-Yes or NoProportion of variation explainedBenefit in accuracy is increased as the
proportion of variation explained increasesCost of technology must pay for itself
Inclusion of DNA information has the potential to:Mitigate riskDecrease generation interval
Benefits will only be realized through cooperation
Resources need to be pooledCollaboration is critical