selection of breeding program an s 426 fall 2007

Selection of Selection of Breeding ProgramBreeding Program

An S 426 An S 426 Fall 2007Fall 2007

Selection of Breeding Selection of Breeding ProgramProgram

Setting of goals is of major importance Setting of goals is of major importance and includes goals for:and includes goals for:

1. Reproduction1. Reproduction2. Calf performance2. Calf performance3. Income3. Income4. Etc.4. Etc.

Breeding management will impact each of Breeding management will impact each of above in varying degrees:above in varying degrees:

1. Breeding management practice with 1. Breeding management practice with greatestgreatest

impact on reproduction is crossbreedingimpact on reproduction is crossbreeding2. Selection is best management practice for2. Selection is best management practice for

improving carcass quality improving carcass quality


Once goals established, herd assessmentOnce goals established, herd assessmentis needed – where is herd atis needed – where is herd at

1.1. Determine breed makeupDetermine breed makeup2.2. Determine production level – need accurate Determine production level – need accurate recordsrecords3.3. Determine average weight and frame size Determine average weight and frame size of cowof cow

herdherd

Larger frame cows have higher Larger frame cows have higher maintenancemaintenance

costscosts

Table 1. Frame relationship to mature size and carcass Table 1. Frame relationship to mature size and carcass weightweight

Yearling Hip Height (in)Yearling Hip Height (in) Expected Expected Weight (lbs)Weight (lbs)

Frame Frame Bulls Bulls HeifersHeifers Mature Mature Steer Steer Steer SteerScore Score CowsCows HarvestHarvestCarcassCarcass 33 45 45 43 43 10251025 950 950 600600 44 47 47 45 45 11001100 10501050 660660 55 49 49 47 47 11751175 11501150 725725 66 51 51 49 49 12451245 12501250 785785 77 53 53 51 51 13201320 13501350 850850 88 55 55 53 53 13951395 14501450 915915 99 57 57 55 55 14651465 15501550 975 975

Figure 1. Comparison of growth curves of small and large Figure 1. Comparison of growth curves of small and large framed cattle.framed cattle.


Larger frame feedlot cattleLarger frame feedlot cattle1. Grow at faster rate1. Grow at faster rate

2. Require greater amounts of feed and in 2. Require greater amounts of feed and in feedyardfeedyard

longer, thus greater expenseslonger, thus greater expenses

3. Heavier finish weights generate more income3. Heavier finish weights generate more income

4. Real problem if variation in frame sizes in 4. Real problem if variation in frame sizes in samesame

feedyard, may need to sort for:feedyard, may need to sort for:a.a.b.b.


Genetic changeGenetic change1. Genetic change may not result in improved 1. Genetic change may not result in improved animalsanimals2. Genetic improvement means superior animals 2. Genetic improvement means superior animals withwith

greater profitabilitygreater profitability

Brought about in two ways:Brought about in two ways:1.1.2.2.


Selection – factors affecting:Selection – factors affecting:1. Variation –1. Variation –2. Heritability –2. Heritability –3. Selection differential –3. Selection differential –4. Generation interval –4. Generation interval –

Predicting genetic change =Predicting genetic change =Genetic change per year =Genetic change per year =

Progress through selection dependent uponProgress through selection dependent uponnumber of traits selectednumber of traits selected

where n = number of traits where n = number of traits selectedselected


Single-vs. multiple-trait selectionSingle-vs. multiple-trait selection

Single-trait selection produces rapid genetic change, Single-trait selection produces rapid genetic change, butbut

unfortunately likely results in undesirable changes inunfortunately likely results in undesirable changes incorrelated traitscorrelated traits

Increasing frame size resulted in increased:Increasing frame size resulted in increased:1.1.2.2.3.3.4.4.


Multiple-trait selection first step towards Multiple-trait selection first step towards more effective selection, but challenges more effective selection, but challenges remain:remain:

1. Rate of improvement in any one trait 1. Rate of improvement in any one trait decreasesdecreases

2. Unfavorable genetic correlations remain for 2. Unfavorable genetic correlations remain for economiceconomic

relative traits (ERT)relative traits (ERT)


Multiple-trait selection first step towards more Multiple-trait selection first step towards more effective selection, but challenges remain:effective selection, but challenges remain:

3.3. MethodsMethodsa.a. Tandem – emphasis on one trait until desired Tandem – emphasis on one trait until desired levellevel

attained and then move to next traitattained and then move to next traitb.b. Independent culling Independent culling - choosing minimum or- choosing minimum or

maximum levels for each traitmaximum levels for each trait- more traits added, more relaxation occurs in order- more traits added, more relaxation occurs in order

to find animals meeting criteriato find animals meeting criteria- once thresholds identified, application of this- once thresholds identified, application of this

method is easy and popularmethod is easy and popular


3.3. MethodsMethods

c.c. Selection indexes – incorporate the cost and Selection indexes – incorporate the cost and incomeincome

resulting from productionresulting from production1.) A description of every index should include:1.) A description of every index should include:

a.) Traits included in the indexa.) Traits included in the indexb.) Description of information used in the b.) Description of information used in the

index, suchindex, suchas EPD or individual phenotypic performanceas EPD or individual phenotypic performance

c.) source of economic information and c.) source of economic information and performanceperformance

levels used to calculate economic weightslevels used to calculate economic weightsd.) Relative economic emphasis of each trait d.) Relative economic emphasis of each trait

to the overall indexto the overall index


c.c. Selection indexes – incorporate the cost and Selection indexes – incorporate the cost and incomeincome

resulting from productionresulting from production

2.)2.) Successful application of generalized Successful application of generalized indexes reliesindexes relies

on logical implementation:on logical implementation:

a.) Identify production and marketing systema.) Identify production and marketing system1.) When will animals be marketed (at what 1.) When will animals be marketed (at what

age)age)2.) How will animals be marketed2.) How will animals be marketed3.) What is current performance and genetic 3.) What is current performance and genetic

level oflevel ofherdherd


c. c. Selection indexes – incorporate the cost and incomeSelection indexes – incorporate the cost and incomeresulting from productionresulting from production

2.)2.) Successful application of generalized indexes reliesSuccessful application of generalized indexes relieson logical implementation:on logical implementation:

b.)b.) Identify the index appropriate to the productionIdentify the index appropriate to the productionsystem outlined above - questions to be addressedsystem outlined above - questions to be addressed

1.) What traits are included in the index1.) What traits are included in the index2.) What are the relative economic values used to2.) What are the relative economic values used to

weigh the traitsweigh the traits3.) Decide on the appropriate index for evaluation3.) Decide on the appropriate index for evaluation

based on the most similarity between above points 1 and 2 based on the most similarity between above points 1 and 2


c.c. Selection indexes – incorporate the cost and incomeSelection indexes – incorporate the cost and incomeresulting from productionresulting from production

3.)3.) Most breed selection indexes are generalized forMost breed selection indexes are generalized foroverall breed improvement and use average costs andoverall breed improvement and use average costs andincome from production rather than accounting for aincome from production rather than accounting for aspecific producer’s marketing and production systemsspecific producer’s marketing and production systems

a.) Has led to the development of Interactivea.) Has led to the development of InteractiveDecision Support (IDS) systems which allow breeders toDecision Support (IDS) systems which allow breeders toinput parameters specific to their production systems – twoinput parameters specific to their production systems – twoclasses:classes:


1.)1.) Herd – level systems Herd – level systems

a.)a.) Designed to evaluate overall genetic Designed to evaluate overall genetic changes in herdchanges in herd

level – not individualslevel – not individuals

b.)b.) Angus Assoc. Optimal Milk Model – Angus Assoc. Optimal Milk Model – designed fordesigned for

producers to decide the appropriate range of milk producers to decide the appropriate range of milk EPDEPD

given the mature weight of their cows, annual cow given the mature weight of their cows, annual cow costscosts

and variability in feed resourcesand variability in feed resources


2.)2.) Individual animal systemsIndividual animal systems

a.)a.) Designed to evaluate individual animal Designed to evaluate individual animal selectionselection

decisions and the impact of those decisions on decisions and the impact of those decisions on profitabilityprofitability

b.)b.) Charolais Assoc. Terminal Sire Profitability Charolais Assoc. Terminal Sire Profitability IndexIndex

(TS) – designed to evaluate the selection of sires (TS) – designed to evaluate the selection of sires based onbased on

their relative impact on profitability in a terminal sire their relative impact on profitability in a terminal sire matingmating

system; allows input of current herd productionsystem; allows input of current herd productioncharacteristics and sources of income by the producercharacteristics and sources of income by the producer


Mating systemsMating systems

1.1. Inbreeding –Inbreeding –a. Main genetic effect is to increase the a. Main genetic effect is to increase the

numbernumberof pairs of homozygous genesof pairs of homozygous genes

b. Usually results in a decline in traits b. Usually results in a decline in traits related torelated to

physical fitnessphysical fitness

1.)1.)2.)2.)



2.2. Outbreeding –Outbreeding –a. Main genetic effect is to increase the a. Main genetic effect is to increase the

numbernumberof pairs of heterozygous genesof pairs of heterozygous genes

b. By increasing heterozygosity there is b. By increasing heterozygosity there is aa

tendency to cover up detrimental recessive tendency to cover up detrimental recessive genes andgenes and

improve traits related to physical fitnessimprove traits related to physical fitness1.)1.)2.)2.)



Crossbreeding –Crossbreeding –two reasons for its use:two reasons for its use:

1.1. For certain traits may result in heterosisFor certain traits may result in heterosis2.2. Breed complementarity Breed complementarity


Table 1. Summary of heritability and level of heterosis by trait Table 1. Summary of heritability and level of heterosis by trait type. type. AA

Trait Trait Heritability Heritability Level of HeterosisLevel of HeterosisCarcass / end product Carcass / end product High High Low Low Skeletal measurements Skeletal measurements (0 to 5 %) (0 to 5 %)Mature weightMature weight Growth rate Growth rate Medium Medium Medium Medium Birth weightBirth weight (5 to 10 %) (5 to 10 %)Weaning weight Weaning weight Yearling weight Yearling weight Milk production Milk production Maternal ability Maternal ability Low Low High High Reproduction Reproduction (10 to 30 %) (10 to 30 %)Health Health Cow longevity Cow longevity Overall cow productivityOverall cow productivity aa Adapted from Kress and MacNeil. 1999 Adapted from Kress and MacNeil. 1999


1.1. For certain traits may result in heterosisFor certain traits may result in heterosis

average of average ofaverage of average ofa. % heterosis =a. % heterosis = crossbred - purebreds crossbred - purebreds x 100 x 100

average of purebreds average of purebreds

1.)1.)

b. Traits not expressing heterosis will equal the b. Traits not expressing heterosis will equal the averageaverage

of the parent breeds for that trait in the crossbred of the parent breeds for that trait in the crossbred offspringoffspring


1.1. For certain traits may result in heterosisFor certain traits may result in heterosisc. Why important in beef cattle businessc. Why important in beef cattle business

1.)1.) Largest benefit to commercial production isLargest benefit to commercial production iscrossbred cows – improves:crossbred cows – improves:

a.)a.)b.)b.)c.)c.)d.)d.)

d.d. Keys for successful crossbreeding program:Keys for successful crossbreeding program:1.)1.)2.)2.)

e.e. Crossbreeding systemsCrossbreeding systems


2.2. Breed complementarity – implies using Breed complementarity – implies using breeds inbreeds in

a crossbreeding program where their a crossbreeding program where their strengths andstrengths and

weaknesses complement one anotherweaknesses complement one another

a. Examplea. Example

1.)1.)


Composite breeds –Composite breeds –

1.1. Maintain heterosisMaintain heterosis2.2. Utilize breed complementarityUtilize breed complementarity3.3. Once formed, can be managed like a Once formed, can be managed like a purebred herdpurebred herd

Formed Formed Retained %Retained % Improved Improved produc. produc. fromfrom maximum heterosis maximum heterosis of cow herd(%) of cow herd(%)2-breed2-breed 50 50 12123-breed3-breed 67 67 15154-breed4-breed 75 75 1717

Table 1. Breed performance levels for seven traits in beef cattle. Table 1. Breed performance levels for seven traits in beef cattle. a,b.a,b.

Table 2. 2004 Adjustment factors to add to EPD of 15 different breeds to Table 2. 2004 Adjustment factors to add to EPD of 15 different breeds to estimate across-breed EPD. estimate across-breed EPD. a,b.a,b.

BreedBreed Birth Weight Weaning WeightBirth Weight Weaning Weight Yearling WeightYearling WeightMilk Milk . . Angus Angus 0.0 0.0 0.0 0.0 0.0 0.0 0.00.0Beefmaster Beefmaster 9.7 9.7 39.0 39.0 37.9 37.9 ------BrahmanBrahman 13.0 13.0 34.8 34.8 -4.4 -4.4 24.624.6BrangusBrangus 5.7 5.7 20.0 20.0 20.4 20.4 ------BraunviehBraunvieh 6.5 6.5 30.0 30.0 13.9 13.9 22.222.2CharolaisCharolais 10.5 10.5 38.4 38.4 53.4 53.4 2.62.6GelbviehGelbvieh 5.4 5.4 7.1 7.1 -21.1 -21.1 1.71.7HerefordHereford 3.4 3.4 -2.0 -2.0 -13.7 -13.7 -17.8-17.8LimousinLimousin 4.5 4.5 1.8 1.8 -19.9 -19.9 -15.9-15.9Maine AnjouMaine Anjou 6.7 6.7 17.6 17.6 5.5 5.5 7.67.6PinzgauerPinzgauer 7.7 7.7 28.3 28.3 25.5 25.5 6.16.1Red AngusRed Angus 3.6 3.6 -1.4 -1.4 0.7 0.7 -7.8-7.8South DevonSouth Devon 6.7 6.7 21.7 21.7 40.8 40.8 3.53.5SalersSalers 4.9 4.9 30.7 30.7 46.1 46.1 9.09.0Shorthorn Shorthorn 7.8 7.8 31.4 31.4 44.5 44.5 12.112.1Simmental Simmental 6.4 6.4 22.4 22.4 21.9 21.9 10.010.0TarentaiseTarentaise 3.6 3.6 30.1 30.1 13.4 13.4 17.817.8

aa Van Vleck and Cundiff, 2004 Van Vleck and Cundiff, 2004b b Updates to across-breed EPD adjustments can be found at Updates to across-breed EPD adjustments can be found at

www.beefimpovement.orgwww.beefimpovement.org

Table 3. Average across-breed EPD for nonparent animals born in 2002-2003 Table 3. Average across-breed EPD for nonparent animals born in 2002-2003 by breed. by breed. a.a.

BreedBreed Birth Weight Weaning WeightBirth Weight Weaning Weight Yearling WeightYearling WeightMilk Milk .. Angus Angus 2.6 2.6 35 35 65 65 1717Beefmaster Beefmaster 10.1 10.1 45 45 49 49 ------BrahmanBrahman 15.1 15.1 51 51 22 22 3232BrangusBrangus 7.7 7.7 41 41 54 54 ------BraunviehBraunvieh 7.6 7.6 37 37 21 21 2222CharolaisCharolais 12.0 12.0 57 57 85 85 88GelbviehGelbvieh 6.4 6.4 44 44 48 48 1919HerefordHereford 7.2 7.2 33 33 46 46 -5-5LimousinLimousin 6.9 6.9 36 36 44 44 22Maine AnjouMaine Anjou 9.2 9.2 34 34 37 37 1111PinzgauerPinzgauer 7.6 7.6 29 29 26 26 55Red AngusRed Angus 4.1 4.1 27 27 49 49 66SalersSalers 7.8 7.8 34 34 60 60 1212Shorthorn Shorthorn 6.7 6.7 44 44 66 66 1111Simmental Simmental 9.7 9.7 65 65 102 102 1818South DevonSouth Devon 6.4 6.4 40 40 45 45 16 16 ..

aa Adjustment using the 2004 across-breed EPD adjustments listed in Table 2. Adjustment using the 2004 across-breed EPD adjustments listed in Table 2.


Successful breeding program depends on:Successful breeding program depends on:

1.1.

2.2.

a.a.

b.b.

selection of breeding program an s 426 fall 2007

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