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Genetic evaluation and best prediction of lactation persistency
 

Genetic evaluation and best prediction of lactation persistency

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At the same level of production cows with high persistency milk more at the end than the beginning of lactation. Best prediction of persistency is calculated as a function of trait-specific standard ...

At the same level of production cows with high persistency milk more at the end than the beginning of lactation. Best prediction of persistency is calculated as a function of trait-specific standard lactation curves and the linear regression of a cow’s test day deviations on days in milk.

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    Genetic evaluation and best prediction of lactation persistency Genetic evaluation and best prediction of lactation persistency Presentation Transcript

    • 200420042005 J. B. Cole * and P. M. VanRaden Animal Improvement Programs Laboratory Agricutural Research Service, USDA, Beltsville, MD jcole@aipl.arsusda.gov Genetic evaluation and best prediction of lactation persistency
    • ADSA 2005: Persistency of lactation (2) Cole and VanRaden 20042005 Introduction  At the same level of production cows with high persistency milk more at the end than the beginning of lactation.  Best prediction of persistency is calculated as a function of trait- specific standard lactation curves and the linear regression of a cow’s test day deviations on days in milk.
    • ADSA 2005: Persistency of lactation (3) Cole and VanRaden 20042005 Best Prediction  Selection IndexSelection Index  Predict missing yields from measured yieldsPredict missing yields from measured yields  Condense daily into lactation yield andCondense daily into lactation yield and persistencypersistency  Only phenotypic covariances are neededOnly phenotypic covariances are needed  Mean and variance of herd assumed knownMean and variance of herd assumed known  Reverse predictionReverse prediction  Daily yield predicted from lactation yieldDaily yield predicted from lactation yield and persistencyand persistency
    • ADSA 2005: Persistency of lactation (4) Cole and VanRaden 20042005 Reliabilities  Definition Squared correlation of estimated with true persistency Same as Rel (breeding value) Single-trait or multi-trait (M, F, P, SCS)
    • ADSA 2005: Persistency of lactation (5) Cole and VanRaden 20042005 Persistency VanRaden 1998 6th WCGALP XXIII:347-350  DefinitionDefinition 305 daily yield deviations (DIM - DIM305 daily yield deviations (DIM - DIMoo)) Uncorrelated with yield by choosingUncorrelated with yield by choosing DIMDIMoo DIMDIMoo werewere 161161,, 159159,, 166166, and, and 155155 forfor M, F, P, and SCSM, F, P, and SCS • DIMDIM00 have increased over timehave increased over time Standardized estimateStandardized estimate
    • ADSA 2005: Persistency of lactation (6) Cole and VanRaden 20042005 Statistical Properties Available data Rel (Y) Rel (P) Corr (Y,P) 305-d Daily 100% 100% .00 305-d Monthly 97 91 .00 305-d Bimonthly 94 82 .00 100-d RIP 76 33 -.78 15-d test 40 27 -1.00
    • ADSA 2005: Persistency of lactation (7) Cole and VanRaden 20042005 Objective  Calculate (co)variance components and breeding values for persistency of milk (PM), fat (PF), protein (PP), and SCS (PSCS) in Holsteins  Estimate genetic correlations among persistency and yield traits
    • ADSA 2005: Persistency of lactation (8) Cole and VanRaden 20042005 Data  8,682,138 lactation records from 4,375,938 Holstein cows calving since January 1, 1997  Best prediction of persistency Milk (M), fat (F), protein (P), SCS Floor and ceiling of ± 4.0 Phenotypic reliability ≥ 50%  1st - 5th lactations (1st required)
    • ADSA 2005: Persistency of lactation (9) Cole and VanRaden 20042005 Cow with Average Persistency 0 5 10 15 20 25 0 30 60 90 120 150 180 210 240 270 300 Days in Milk Kilograms Best Prediction Standard Curve Test Days
    • ADSA 2005: Persistency of lactation (10) Cole and VanRaden 20042005 Highest Cow Persistency 0 10 20 30 40 50 60 70 80 90 100 0 30 60 90 120 150 180 210 240 270 300 Days in Milk Kilograms Best Prediction Standard Curve Test Days
    • ADSA 2005: Persistency of lactation (11) Cole and VanRaden 20042005 Lowest Cow Persistency 0 10 20 30 40 50 60 70 80 90 100 0 30 60 90 120 150 180 210 240 270 300 Days in Milk Kilograms Best Prediction Standard Curve Test Days
    • ADSA 2005: Persistency of lactation (12) Cole and VanRaden 20042005 Model Repeatability animal model: yijkl = hysi + lacj + ak + pek + β(dojk) + eijkl yijkl = persistency of milk,fat, protein, or SCS hysi = fixed effect of herd-year-season of calving I lacj = fixed effect of lactation j ak = random additive genetic effect of animal k pek = random permanent environmental effect of animal k dojk = days open for lactation j of animal k eijkl = random residual error ijkljkkkjiijkl e)β(dopealachysy +++++= ijkljkkkjiijkl e)β(dopealachysy +++++=
    • ADSA 2005: Persistency of lactation (13) Cole and VanRaden 20042005 (Co)variance Components σa 2 σpe 2 σe 2 h2 rept PM 0.10 0.09 0.85 0.10 0.18 PF 0.07 0.08 0.79 0.07 0.15 PP 0.08 0.07 0.70 0.09 0.17 PSCS 0.02 0.03 0.64 0.03 0.07
    • ADSA 2005: Persistency of lactation (14) Cole and VanRaden 20042005 Correlations Among Persistency Traits PM PF PP PSCS PM 0.83 0.87 -0.48 PF 0.72 0.82 -0.41 PP 0.91 0.72 -0.58 PSCS -0.19 -0.11 -0.14 1 Genetic correlations above diagonal, residual correlations below diagonal.
    • ADSA 2005: Persistency of lactation (15) Cole and VanRaden 20042005 Phenotypic Correlations Among Persistency and Yield M F P SCS PM 0.03 0.07 0.07 -0.03 PF 0.05 -0.02 0.08 -0.03 PP 0.04 0.08 0.05 -0.03 PSCS 0.05 0.02 0.04 -0.03
    • ADSA 2005: Persistency of lactation (16) Cole and VanRaden 20042005 Genetic Correlations Among Persistency and Yield M F P SCS PM 0.05 0.10 0.03 -0.04 PF 0.12 0.12 0.00 0.00 PP -0.02 0.08 -0.09 -0.11 PSCS -0.23 -0.28 -0.20 0.41
    • ADSA 2005: Persistency of lactation (17) Cole and VanRaden 20042005 Distribution of Sire PTA 0 10 20 30 40 50 60 70 -0.93 -0.80 -0.66 -0.53 -0.39 -0.26 -0.12 0.01 0.15 0.29 0.42 0.56 PTA PM Frequency 0 10 20 30 40 50 60 70 -0.73 -0.61 -0.50 -0.39 -0.28 -0.17 -0.06 0.05 0.16 0.28 0.39 0.50 PTA PF Frequency 0 10 20 30 40 50 60 70 -0.70 -0.59 -0.48 -0.37 -0.27 -0.16 -0.05 0.05 0.16 0.27 0.38 0.48 PTA PP Frequency 0 10 20 30 40 50 60 70 80 -0.35 -0.29 -0.24 -0.18 -0.13 -0.07 -0.01 0.04 0.10 0.16 0.21 0.27 PTA PSCS Frequency
    • ADSA 2005: Persistency of lactation (18) Cole and VanRaden 20042005 Conclusions  Heritabilities and repeatabilities are low to moderate  Routine genetic evaluations for persistency are feasible  The shape of the lactation curve may be altered without affecting production