Performance Evaluation

SUSAN SCHOENIANSheep & Goat Specialist

University of Maryland Extensionsschoen@umd.edu - www.sheepandgoat.com

2013 Winter Webinar Series: Breeding Better Sheep & Goats

Making better sheep and goatsWHERE WE’VE BEEN

PhenotypeGenotype + environment

Visual appraisalHow animal looks

Subjective criteriaWhat we see

WHERE WE NEED TO GO

GenotypeGenetic merit

Performance evaluationHow animal performs

Objective criteriaWhat we measure

Performance evaluationIndividual records Genetic predictors

• EPDs• EBVs• DHIR

• Adjusted weights• Milk yield• Fleece weight • Staple length• Ultrasound data• Fecal egg counts• FAMACHA© scores• Fiber analysis• Performance ratios

Performance evaluation: set goals• What is the primary purpose of

your sheep and/or goat enterprise?

• If you are a seedstock producer, what is the primary role of your breed(s) in commercial production systems?

• Determine which traits are most important to your herd, flock, or breed.

Terminal sire

SizeGrowth rate

Carcass merit

Offspring survival

Libido

Maternal

Fertility

Prolificacy

Mothering

Milk production

Litter weight

Fitness

Commercial fiber

Grease weight

Clean weight

YieldStaple length

Fiber diameter

DairyMilk yieldPercent proteinPercent fatUdder conformationLinear appraisal

ShowSizeConformation

StructureEye appealBreed character

Niche fiberColorLusterHandleCrimp Staple lengthFiber diameter

Commercial meatLitter weightGrowth rateFitnessLongevityMarket acceptance

SeedstockVaries by breedScrapie genotype

Your selected traits

• Are they economically important to your farm and/or breed?

• Can the traits be objectively measured (when and how)?

• Will they respond to selection or (crossbreeding)?

Performance evaluation starts with animal identification

Options1. Ear notches2. Tattoos3. Electronic4. Ear tags5. Paint brands6. Neck chains

Mor

e pe

rman

ent

To make genetic improvement, you have to keep good records.

• Everyone should keep basic reproductive and health records.

• What additional records you keep (and data you collect) will depend upon your production emphasis and breed.

• A central performance test will collect data on potential sires.

Record keeping optionsHandwritten

1. Pocket book2. Notebook 3. Chalkboard

Using a computer• Spreadsheet• Database• Third party software• Online• University

Keeping records by hand (pencil)

Spreadsheets for record keeping

Record keeping software http://www.sheepandgoat.com/software.html#flock

Performance evaluation

• Records aren’t very useful unless you use them for decision- making purposes.– Ram/buck selection– Selection of replacements– Keep/cull decisions– Decisions to castrate

• Records need to be properly analyzed and used to be effective for genetic improvement.

An important aspect of performance evaluation

Contemporary group• Comparisons should only be

made between animals in the same contemporary group.

• A group of the same breed, born within +/- two weeks with each other, raised at the same location or in the same herd or flock, of the same sex and managed alike from birth until time of measurement.

Factors affecting contemporary groups

• Breed percentage• Sex• Lambing/kidding period• Location• Management factors– Health – Nutrition

Animals which receive preferential treatment should be placed within

their own contemporary group.

Another important aspect of performance evaluation

Adjustments• Sometimes records (data)

need to be “adjusted” to remove environmental effects.

• Records are adjusted to a standard animal or weight

– Weaning weightsSingle male offspring raised by a 3-6 year old dam.

– Loin eye area125-lb. market lamb100-lb. Katahdin ram lamb

Calculating adjusted weaning weights1. Adjust weaning weights to a

common day of age (usually 60, 90, or 120 days of age)

a) Determine animal’s pre-weaning average daily gain (ADG).

b) Multiply pre-weaning ADG by common age.

c) Add birth weight

2. Adjust weaning weight for sex of offspring, age of dam, and type of birth and rearing

a) Multiply age-corrected weaning weight by appropriate adjustment factor.

Adjustment factors allow animals to be fairly compared by removing non-genetic factors.

Adjustment factors vary by species and breed. When breed-specific adjustment factors are not available, generic adjustment factors can be used.

Adjustment factors for meat goats (Boer)

Example• Calculate the 60-day adjusted weaning weight for a Dorset

ram lamb born on March 1 and weaned on June 10. The lamb was born and raised as a twin. His birth weight was 10 lbs. He weighed 70 lbs at weaning. His dam was 2 years old.

1) Determine pre-weaning ADG2) Multiply pre-weaning ADG weight by common age3) Add birth weight back in4) Multiply age-corrected weight by adjustment factor (see TABLE)

Example

1) Determine pre-weaning ADG

(weaning weight - birth weight*) age (in days)

(70 - 10) 71 d = 0.85 lb/d

Born March 1Born/raised twinWeaned June 10Birth weight - 10 #Weaning weight - 70 #Age of dam - 2 yrs

*If birth weight is not known, a weight per day of age (WDA) can be calculated instead.

Example

2) Multiply pre-weaning ADG weight by common age(0.85 x 60 d) = 51.0 lbs.

3) Add birth weight back in*51.0 lbs. + 10 lbs. + 61.0 lbs.

Born March 1Born/raised twinWeaned June 10Birth weight - 10 #Weaning weight - 70 #Age of dam - 2 yrs

*If WDA was calculated instead of pre-weaning ADG, do not add a birth weight back in.

Example

4) Multiply age-corrected weight by adjustment factor

61.0 lbs. x adjustment factor

Born March 1Born/raised twinWeaned June 10Birth weight - 10 #Weaning weight - 70 #Age of dam - 2 yrs

61.0 lbs. x 1.16 = 70.8 lbs.

Performance ratios

• The percent above or below the average of the contemporary group.

• Performance ratioIndividual performance average performance of group x 100

Example: performance ratioWhat is the WW ratio for buck #6

ID Adj. WW123456789

10Avg

44383250484540414039

41.7

Individual performanceAverage performance of group

45 lbs41.7 lbs

x 100

x 100

= 108 %

Selecting for parasite resistance• Measure fecal egg counts when

animals are between 4 and 12 months of age.

• Compare average fecal egg count of an individual lamb or kid to the group average (at least 15-25 animals).

• A high worm load is needed to select for parasite resistance (> 500 epg avg.)

• More measurements more selection accuracy

• A resistant male is needed to make much progress.

Can only compare animals in same contemporary group.

Selecting for parasite resistanceSIRE SELECTION• Choose sire with lowest

average progeny FEC.

REPLACEMENT SELECTION• Choose replacements from

sire(s) with lowest average FEC (if more than one sire)

• Choose replacements with lowest FECs in group.

How we select for parasite resistance in our buck test

Top 10

Bottom 10

123456789

10

All goats were triple-dewormed (moxidectin + levamisole + albendazole) on 6/2. Twelve days later, the average fecal egg count was near zero.

10987654321

How we select for parasite resilience in our buck test

Top 10

Bottom 10

123456789

10

10987654321

All goats were triple-dewormed (moxidectin + levamisole + albendazole) on 6/2. For the next 8 weeks, the average FAMACHA© score improved and no goat required deworming.

0

What about visual appraisal?Does it matter what the animal looks like?

Absolutely!

There should always be minimum standards for reproductive soundness and structural correctness.• Reproductive soundness

a) Testiclesb) Teethc) Teats and udder

• Structural correctnessa) Feet and legsb) Jaw setc) Conformation

Emphasis on visual appraisalCommercial Show ring• Minimum standards• More stringent standards for

rams and bucks• Some (?) correlation with

productivity and longevity, especially with dairy females.

• Many fleece traits are subjectively evaluated.

• Very important• Economic trait• Some traits are highly

heritable.• Low correlation with

productivity.

Visual appearance is still a very important aspect of market acceptance.

Final webinar: Feb 19, 7 pm EST“Advanced Genetic Improvement”