VALUE OF COMPOSITE BREEDS IN U'S' SHEEP PRODUCTION

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VALUE OF COMPOSITE BREEDS IN U.S. SHEEP PRODUCTION
KREG LEYMASTER USDA, ARS, U.S. MEAT ANIMAL
RESEARCH CENTER CLAY CENTER, NE
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DEFINITION OF A COMPOSITE BREED
A NEW BREED FORMED BY CROSSING TWO OR MORE
BREEDS, THEN SELECTING WITHIN THE NEW CROSSBRED
POPULATION
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APPEAL OF COMPOSITE BREEDS
SIMPLE AND PRACTICAL BREEDING PROGRAM TO USE
BREED AND HETEROSIS EFFECTS
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LAMB AND EWE HETEROSIS EFFECTS ()
TRAIT LAMB EWE
PERCENTAGE LAMBING 2.6 8.7 NUMBER
BORN 2.8 3.2 LAMB SURVIVAL 9.8 2.7 WEANING
WEIGHT 5.0 6.3 WEIGHT OF LAMBS WEANED PER EWE
EXPOSED 17.8 18.0
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HETEROSIS AFFECTS LOWLY-HERITABLE TRAITS
PERCENTAGE LAMBING NUMBER BORN LAMB
SURVIVAL STAYABILITY RAM FERTILITY
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FIRST CROSS (F1)
HETEROSIS
BREED B
PUREBRED AVERAGE
BREED A
PERFORMANCE OF PURE BREEDS AND FIRST CROSS
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FIRST CROSS (F1)
LOSS OF HETEROSIS
COMPOSITE (F2)
RETAINED HETEROSIS
BREED B
PUREBRED AVERAGE
BREED A
PERFORMANCE OF PURE BREEDS AND 2-BREED COMPOSITE
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HETEROSIS REALIZED BY TERMINAL CROSSBREEDING
SYSTEMS
HETEROSIS DESCRIPTION OF EWE MATING
TYPE LAMB EWE
PUREBRED A x T 100 0 FIRST-CROSS (A x B) x
T 100 100 2-BREED ROTATION ABR x T
100 67 3-BREED ROTATION ABCR x T 100 86 2-BREED
COMPOSITE ABC x T 100 50 3-BREED COMPOSITE ABCC x
T 100 62 4-BREED COMPOSITE ABCDC x T 100 75
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RELATIVE PRODUCTION OF CROSSBREEDING SYSTEMS
GENERAL GENETIC TYPE PURPOSE
TERMINAL
PUREBRED 100 122 FIRST-CROSS 117 150 2-BREED
ROTATION 134 146 3-BREED ROTATION 143 153 2-BREED
COMPOSITE 125 141 3-BREED COMPOSITE 131 145 4-BREE
D COMPOSITE 138 150
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FIRST-CROSS TERMINAL SYSTEM
C EWES X C RAMS
½ C ¼ T ¼ F EWES X TERMINAL SIRES
C EWES X ½ T ½ F RAMS
EWES
EWES
SELL WETHERS
SELL WETHERS
SELL LAMBS
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COMPOSITE TERMINAL SYSTEM
POLYPAY EWES X POLYPAY RAMS
POLYPAY EWES X TERMINAL SIRES
EWES
SELL WETHERS
SELL LAMBS
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RELATIVE COMPLEXITY OF TERMINAL CROSSBREEDING
SYSTEMS
BREEDING FLOCKS/ BREED RELATIVE EWE
TYPE RAM BREEDS COMPOSITION PRODUCTION
PUREBRED 2 STABLE 122 FIRST-CROSS 3 STABLE 150 2-B
REED ROTATION 3 1/3, 2/3 146 3-BREED
ROTATION 4 4/7, 2/7, 1/7 153 2-BREED
COMPOSITE 2 STABLE 141 3-BREED COMPOSITE 2 STABLE
145 4-BREED COMPOSITE 2 STABLE 150
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TAKE-HOME MESSAGE
COMPOSITE BREEDS PROVIDE A SIMPLE AND PRACTICAL
METHOD TO USE BREED AND HETEROSIS EFFECTS
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INDUSTRY EVALUATION OF COMPOSITE RAMS TIM
INDART, CLOVIS, CALIFORNIA
COMMERCIAL OPERATION IN SAN JOAQUIN
VALLEY. BREEDS MAY THROUGH AUGUST ON WHEAT
STUBBLE (HOT, HUMID). POOR FERTILITY AND
HARDINESS OF SUFFOLK AND TEXEL RAMS. USES 3/8
FINNSHEEP RAMS TO GET ACCEPTABLE FERTILITY
RATE. COMPROMISES LAMB PERFORMANCE (GROWTH,
CARCASS). DEVELOPED AGREEMENT TO PROVIDE 25
COMPOSITE RAMS. EXPOSED 1,000 EWES PER SIRE
BREED IN 2002 2003. 87 FERTILITY FOR
COMPOSITE, 84 FOR CONTROL
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SIREMAX - A TERMINAL SIRE COMPOSITE
LIMITATIONS OF TRADITIONAL SIRE
BREEDS (LONGEVITY, RAM FERTILITY, LAMB
SURVIVAL). BREEDERS WERE NOT SOLVING THESE
PROBLEMS. SOLUTION - CREATE A NEW SIRE BREED
BASED ON FUNDAMENTAL GENETIC PRINCIPLES. GROUP
OF PRODUCERS MET IN 1992 AND DESIGNED A PLAN TO
CREATE NEW SIRE BREED. FOUNDATION SHEEP WERE
PURCHASED AND PLAN IMPLEMENTED TO DEVELOP SIREMAX
PROGRAM. WWW.SIREMAX.COM
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SIREMAX RAMS
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CREATION OF AN EASY-CARE MATERNAL LINE OF HAIR
SHEEP OBJECTIVE CREATE, EVALUATE, AND DEVELOP
AN EASY-CARE MATERNAL LINE OF HAIR SHEEP FOR USE
IN LOW-INPUT PRODUCTION SYSTEMS. RELEVANCE
ADDRESS INDUSTRY GOALS TO INCREASE REPRODUCTIVE
RATE AND REDUCE LABOR REQUIREMENTS. APPROAC
H USE EXPERIMENTAL RESULTS TO DETERMINE BREED
COMPOSITION. CREATE NEW BREED.
EVALUATE NEW BREED RELATIVE TO KATAHDIN.
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STRATEGY FOR USE OF GENETIC VARIATION
SET BREED COMPOSITION (DIRECT, MATERNAL,
HETEROSIS) TO MEET OPTIMAL LEVELS OF PERFORMANCE
FOR LOWLY HERITABLE FITNESS TRAITS SELECT
WITHIN MATERNAL LINE TO ADDRESS MORE HIGHLY
HERITABLE TRAITS
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RATIONALE FOR BREED COMPOSITION
STRENGTHS OF CROSSBRED ROMANOV EWES PERCENTAGE
LAMBING LENGTH OF SEASONALITY NUMBER BORN LAMB
SURVIVAL STAYABILITY USE AS MUCH ROMANOV
GERMPLASM AS PRACTICAL IDENTIFY CONTRIBUTING
BREEDS THAT COMPLEMENT ROMANOV GERMPLASM STRATEGY
FAVORS BREEDS WITH RELATIVELY LOW PROLIFICACY
BUT HIGH MILK PRODUCTION, TO ACHIEVE ACCEPTABLE
LEVELS OF LAMB SURVIVAL
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REQUIREMENTS TO DEVELOP A NEW BREED
WELL-CONCEIVED VISION STATEMENT. THOROUGH
KNOWLEDGE OF GENETIC PRINCIPLES. BREEDING FLOCKS
OF AT LEAST 500 EWES AND 25 RAMS. 25 BREEDING
PENS/PASTURES FOR SINGLE-SIRE MATINGS. DATA
RECORDING AND GENETIC ANALYSIS SYSTEMS. RELEVANT
SELECTION OBJECTIVES.
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MAJOR UNDERTAKING
FEW SHEEP PRODUCERS HAVE THE NECESSARY
RESOURCES. PRODUCERS CAN WORK TOGETHER AND POOL
RESOURCES . COOPERATORS MUST COOPERATE, MEET
OFTEN, DEVELOP RULES AND PROCEDURES IN
WRITING, EVALUATE PROGRESS, RESOLVE
CONFLICTS, AND BE PATIENT.
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ALTERNATIVE APPROACH
CONVINCE UNIVERSITY ADMINISTRATORS OF
POTENTIAL ECONOMIC IMPACT AND SEEK THEIR
INVOLVEMENT IN DEVELOPMENT OF A NEW BREED
CUSTOMIZED TO MEET NEEDS OF UTAH PRODUCERS
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PRODUCER-FRIENDLY ARTICLE
WWW.USMARC.USDA.GOV SHEEP RESEARCH
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FIGURE 1. LAMB CROP IN UTAH BY YEAR