Matt Spangler Beef Genetics Specialist University of Nebraska-Lincoln

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