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This is the 4th webinar in a five part series on Breeding Better Sheep & Goats. This presentation entitled "Performance Evaluation" was given by Susan Schoenian, University of Maryland Extension Sheep & Goat Specialist.
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Performance Evaluation
SUSAN SCHOENIANSheep & Goat Specialist
University of Maryland [email protected] - 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
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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”