Genetic evaluation and best prediction of lactation persistency

460 views

Published on

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.

Published in: Science, Business, Technology
0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total views
460
On SlideShare
0
From Embeds
0
Number of Embeds
6
Actions
Shares
0
Downloads
11
Comments
0
Likes
0
Embeds 0
No embeds

No notes for slide

Genetic evaluation and best prediction of lactation persistency

  1. 1. 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
  2. 2. 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.
  3. 3. 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
  4. 4. 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)
  5. 5. 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
  6. 6. 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
  7. 7. 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
  8. 8. 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)
  9. 9. 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
  10. 10. 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
  11. 11. 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
  12. 12. 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 +++++=
  13. 13. 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
  14. 14. 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.
  15. 15. 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
  16. 16. 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
  17. 17. 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
  18. 18. 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

×