SUSAN SCHOENIANSHEEP & GOAT SPECIALIST

UNIVERSITY OF MARYLAND EXTENSIONSSCHOEN@UMD.EDU

WWW.SHEEPANDGOAT.COM

A Beginner’s Guide to EBVs

What is an EBV?

EBV is an acronym. It stands for Estimated Breeding Value.

An EBV quantifies the genetic merit of an animal (for breeding).

It is a mathematical, computer-generated prediction of an animal for economically-important traits.

For anyone familiar with EPDs (used in cattle), an EBV is twice the value of an EPD, as P=progeny.

EBVs can be calculated for any trait for which data can be collected.

Another acronym. What is NSIP?

NSIP stands for National Sheep Improvement Program.

NSIP is the organization that provides EBVs for the US sheep and goat industry.

NSIP data is now processed by Sheep Genetics in Australia (also referred to as LAMBPLAN).

Other animal industries and countries have similar programs.

Small ruminant dairy producers should use DHIA, not NSIP.

What traits does NSIP measure?

EBVs currently available for US sheep and

goats

Reproductive traitsNumber of lambs born (NLB, %)Number of lambs weaned (NLW, %)Scrotal circumference (SC, cm)

Growth traitsBirth weight (BWT, kg)Weaning weight (WWT, kg)Maternal weaning weight (MWWT, kg)Post-weaning weight (PWWT, kg)Yearling weight (YWT, kg )

Carcass traitsLoin muscle depth (EMD, mm)Fat depth (CF, mm)

Wool traitsFleece weight (GFW, %)Fiber diameter (FD, μ)Staple length (SL, mm)

Parasite resistanceWorm egg count (WEC, %)

IndexesCarcass Plus index, %USA Hair Index, %USA Maternal Index, %USA Range Index, %

Understanding the numbers

Source: Ram Buyer’s Guide, NSIP, 2016

Understanding the numbers

Understanding the numbers

1. Flock EBVs 2. (Across-flock) EBVs

Within-flock EBVs are calculated when a flock is not connected to other NSIP flocks.

EBVs on individual animals can only be compared to animals in the same flock.

Flock has genetic linkages with other NSIP flocks.

EBVs from individual animals can be compared to EBVs from individuals in other flocks, regardless of geographic location or production system.

There are two kinds of EBVs.

THESE CHARACTERISTICS ARE THE ANIMAL’S PHENOTYPE . THEY INCLUDE TRAITS WHICH

WE CAN MEA SURE OR OBSERVE .

All animals have a set of characteristics that represent

their value to a producer.

Number bornBirth weightWeaning weightFiber diameterLoin depthFecal egg count Frame size. . . and many more.

Genetics

Phenotype is the result of the animal’s genetics (genotype), as well as the

environment in which it was/is raised.

Phenotype Environment

Most (75-90%) of the differences we see between animals are the result of

environment, management, and/or chance.

The remain ing d ifferences are the resu l t o f genet ics .

Th is may seem smal l , but genet ics i s permanent and compounding .

EBVs he lp ident i fy the port ion of d ifferences that are due to genet ics .

EBVs are more accurate than on - farm and centra l i zed tes t ing .

How are EBVs are calculated?

EBVs are calculated by accounting for known sources of variation for each (phenotypic) trait.

Environment Genetics

Heritability Genetic relationships Genetic correlations

Production environment Fixed effects

PenPastureDietHealthManagement

Adjustment factors are used to correct for fixed effects of differences in environment.

Adjustment factors standardize traits (e.g. weights) to a common birth and rearing type.

Type of birth (single) Type of rearing (single) Age of dam (3-6 years)

Environment is a large source of variation.

The effect of genetics on a trait varies.

The variation in the proportion of genetics on a certain trait is called heritability (h2).

ReproductiveLow (5-20%)

GrowthModerate (10-50%)

CarcassModerate (10-45%)

WoolModerate to high (25-55%)

LactationModerate (15-35%)

Parasite resistanceModerate to high (25-50%)

Number of lambs born is only ~10% heritable.

EBVs account for relationships between animals.

Offspring inherit roughly 50% of their genes from their sire and 50% of their genes from their dam.

Half-sibs share about 25% of their genes.

First cousins share approximately 12.5% of their genes.

Even distantly-related animals share some genes.

EBVs account for genetic correlations.

Most performance traits are not controlled by a single gene, but rather have multiple genes that control the genetic portion of trait expression.

Positive correlations mean that increases in one trait will result in increases in another trait. For example: birth weight (BWT)

and weaning weight (WWT) have a genetic correlation of 0.3.

On the other hand, some traits have negative genetic correlations, such as staple length (SL) and fiber diameter (FD).

EBVs are calculated from…

1. Data for trait measured.E.g. weaning weight

2. Data from correlated traits.birth weight, post-weaning weight

3. Date from relatives.sire, dam, siblings, cousins, distant relatives

4. Factoring in heritability.10-50%

EBVs are comparisons to the flock or NSIP breed average.

Strength of EBVs is highly dependent on three concepts.

CONTEMPORARY GROUPSGENETIC

CONNECTIONSACCURACY

What is a contemporary group?

A group of lambs or kids that are born within 45 days of each other and have been managed the same way.

Same feed Same pasture Same health protocol

Good contemporary groups have at least two sires and enough offspring (usually at least 20) from each sire.

A “management” group.

These aren’t contemporary groups.

Different breeds. Offspring born in different seasons

or more than 45 days apart. Offspring whose dams were

separated for preferential feeding or grazing.

Creep-fed vs. non creep-fed animals.

Offspring raised in different locations.

Fostered lambs and kids. Offspring removed for artificial

rearing.

Importance of genetic linkagesWhen animals share some

percentage of the same genetics.

Genetic linkages provide a means to compare the performance of animals in different flocks.

Genetic linkages are best accomplished by using the same male in two or more participating flocks/herds.

I’m coming to your farm

next.

What are EBV accuracy values?

A measure of confidence in an animal’s EBV.

How representative is the EBV of the animal’s true breeding value?

Accuracy values range from 0 to 100.

The higher the accuracy value is, the more confident we can be in the EBV.

Accuracy values are affected by… The amount of performance data that is

available on the animal and its parents. The heritability of the trait. The size of the group in which the animal

was compared.

Who should enroll in NSIP?

Purebred producers who want to improve the accuracy of their selection.

Producers whose flocks are large enough to use multiple sires and have enough animals to create meaningful contemporary groups.

Producers who can provide pedigree data (single sire matings) on progeny.

Producers who are willing to measure, record, and submit the required data.

Producers who have or are willing to create genetic linkages with other breeders.

NSIP IS SCIENCE-BASED, INDUSTRY-TESTED.

Breeds most active in NSIPEach breed has a coordinator (maybe 2).

Dorset (9) Hampshire (12) Katahdin (~50) Polypay (~30) Shropshire (8) Suffolk (~30) Targhee (~26)

Other breeds have fewer than 3 flocks enrolled.

Only five meat goat herds are currently enrolled in NSIP.Source: NSIP, Feb. 10, 2016

Can producers with small flocks enroll in NSIP?

Anyone can enroll their flock and herd in NSIP.

Small flocks should purchase or lease rams with EBVs.

Small flocks still need to use two sires for breeding.

Rate of genetic progress will be slower with small flocks.

Flock EBVs instead of (across-flock) EBVs, if no connections to other NSIP flocks.

15 ewes

SIRE A

15 ewes

SIRE B

25 lambsSIRE A

25 lambsSIRE B

30 ewes of same breed

• EB Vs ar e equa l l y benefic ia l to sheep and goat p r oducer s .

• Whi le NSIP u ses sheep te r mino logy ( ewe , r am, an d l amb) , i t cou ld ch an ge i f mor e goa t p roducer s wer e enr o l l ed i n NSI P.

• Sheep Gene t i cs Aus t ra l i a a l so has a KI DPLAN .

• Dr. Ken Andr i e s f rom Ken tucky S ta te Un i ver s i t y i s NSI P coord i na tor f o r goa t s .

I’m a goat producer. Why should I enroll in the

National Sheep Improvement Program?

Purebred producer Commercial producer

Enroll your flock in NSIP and use EBVs to improve your accuracy of selection for economically important traits.

Purchase breeding stock, especially rams, with above average EBVs or indexes (enrolled and non-enrolled flocks; small flocks).

Establish values for your breeding stock.

Purchase males with above-average EBVs or indexes. Direct from breeder NSIP sales

How can I use EBVs in my flock?

Balanced selection Single trait selection

Most common (recommended) practice.

Choose animals that are above-average in all traits.“Breed the best to the best.”

Can use indexes to help make selection decisions. Terminal sire (e.g. Suffolk) Maternal (wool, e.g. Polypay) Maternal (hair, e.g. Katahdin) Maternal (range, e.g. Targhee) Custom

Focus on small number of traits. Correct problem in flock Create elite flock for

specific trait(s).

Riskier goal Need to be beware of

unintended consequences (problems) that can results with single or narrow trait selection.

How can I use EBVs to select better animals?

Match production system and goals to EBVs.

If you sell 60-lb. lambs, it’s better to select for maternal weaning weights than for post-weaning weights.

Organic or pasture-based operations may want to select for parasite resistance (fecal egg counts).

The emphasis in terminal sire breeds (e.g. Suffolk) should be on growth and carcass traits, whereas maternal breeds (e.g. Katahdin, Polypay) should emphasize reproductive traits and maternal weaning weights.

Prolific flocks may want to select for maternal weaning weights to reduce number of orphan lambs.

Required Optional

Date of birth Birth type Rear type Sire and dam info Contemporary (or

(management) groups Birth weight

(within 24 hours)

Weaning weight(avg. 60 days, 45-90 days)

Post weaning weight (90-150 days)

Fleece traits Fecal egg counts

(weaning, 120 days of age) Scrotal circumference

(150-240 days) Ultrasound scan data

What do I need to measure and record?

How do I enroll my flock or herd in NSIP?

Go to NSIP.org Print and fill out the

enrollment form. Send with check to NSIP. Enrollment fees are waived for

first year members and for three years for members younger than 22 (as of 1/1/16).

However, there is a $100 data fee deposit (is refunded after data is submitted).

Start collecting and entering data.

Annual enrollment Data fee

Based on size of flock $100

$2.50 x ewe/doe $25 for additional

breed• Capped at $400- $25 early bird credit

Based on number of lambs (or kids) with post birth measurement. $2.85 per animal,

excluding animals designated as culls or commercials.

Covers lifetime of animal.

How much do EBVs cost?

Flock with 40 ewes or does$100 + (40 x $2.50) = $200

Will EBVs make me money?

The primary purpose of EBVs is to make genetic improvements in your own flock or herd (i.e. to increase profitability).

There is an increasing demand for sheep with EBVs. SW Virginia Ram Test Center of the Nation

NSIP Sale (Iowa) Montana Ram Sale NSIP sale in East [?] Goats (eventually ?)

Ram with an EBV of +5.0 for NLWDaughters will produce 0.05 more lambsThat’s 5 more lambs per 100 lambings5 extra lambs x $150/lamb = $750

Ram with EBV of +5.0 for WWTProgeny will be 2.5 kg (5.5 lbs) heavier at weaning than average5.5 lbs x $2/lb = $11/lamb50 lambs x $11 = $550100 lambs x $11 = $1100

Tips for making NSIP/EBVs work for you.

Collect the right data at the right time

Plan breeding groups to test genetics.

Maintain good contemporary groups.

Cooperate with other NSIP breeders.

Communicate with commercial producers.

Be honestBe patient and trust the

data.

CAN CAN’T

Select ewe and doe replacements for economically-important traits.

Make purchasing decisions. Make culling decisions. Select flock sire(s) Increase the accuracy of selection

for superior performance. Set value of breeding stock. Increase profitability of enterprise. Improve productivity of breed.

Tell if an animal is structurally connect.

Tell if an animal has good conformation.

Tell if an animal has good breed character.

Tell if an animal has a genetic defect (e.g. bad bite).

Replace visual appraisal. Force you to make the right

breeding decisions.

What EBVs can and can’t do

MAYBE, MAYBE NOT

E BVs iden t i f y poor per forming an imal s .

An ima ls w i thou t E BVs cou ld be ge ne t i ca l l y

super io r ( o r i n fe r i o r ) , bu t there i s no way o f know ing .

Are animals with EBVs better than animals without EBVs?

“If you don’t measure it, you can’t manage it.”

N AT I O N A L S H E E P I M P R OV E M E N T P R O G R A Mh t t p : / / n s i p . o r g

KATA H D I N N AT I O N A L SH E E P I M P R OV EM E N T P R O G R A M h t t p : / / w w w. k a t n s i p . c o m /

R A M B U Y I N G G U I D E ( n e w p u b l i c a t i o n )h t t p : / / n s i p . o r g / w p - c o n t e n t / u p l o a d s / 2 0 1 5 / 0 1 /N S I P- R a m - B u y in g - Gu i d e - F I N A L - 1 2 - 2 1 - 1 5 . p d f

SH EE P GE N ET I C S A U ST R A L I Ah t t p : / / w w w. s h e e p g en e t i c s . o r g . a u / H o m e

There is lots of information about EBVs (and NSIP) online.