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Effect of Synchronization Protocols on Days Open and Pregnancy Rate at 120 Days in Dairy Cattle

Effect of Synchronization Protocols on Days Open and Pregnancy Rate at 120 Days in Dairy Cattle. Reproductive Performance. History Decreasing performance over time Negative correlation with production traits Poor performance costly to producers Use of synchronization protocol

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Effect of Synchronization Protocols on Days Open and Pregnancy Rate at 120 Days in Dairy Cattle

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  1. Effect of Synchronization Protocols on Days Open and Pregnancy Rate at 120 Days in Dairy Cattle

  2. Reproductive Performance • History • Decreasing performance over time • Negative correlation with production traits • Poor performance costly to producers • Use of synchronization protocol • Numerous protocols available • Dependent upon herd • Variety of herd applications ADSA-ASAS Joint Meeting 2004 (2)

  3. Objectives • Determine effects of synchronization protocols on genetic parameter estimates for: • Days open (DO) • Pregnancy rate at 120 days (PR120) • Evaluate best approach to analyze reproduction field data with synchronization ADSA-ASAS Joint Meeting 2004 (3)

  4. Traits • Days open (DO) • Includes interval from calving to first breeding (DFB) and the interval from breeding to conception • Current selection on related trait (DPR) • Handles cows that do not breed back • Pregnancy rate at 120 d (PR120) • Categorical trait • Reflects 13 month calving interval • Available before DO, less censoring ADSA-ASAS Joint Meeting 2004 (4)

  5. Data Collection • 64 herds on progeny testing program • Utilized Dairy Comp 305 herd software • 50% sire identification and 75% breeding information • Data requirements: • Recorded fresh event • First complete lactation (max. 6th) • DFB between 37 d and 300 d • DO between 37 d and 500 d • Calving year between 1999 and 2002 ADSA-ASAS Joint Meeting 2004 (5)

  6. Models • Sire models for both traits • Base Model • Fixed effects: lactation, age at freshening (months), herd-year-season • Random effects: sire and residual • Expanded Model • Base model plus fixed effect for synchronization • Interaction Model • Expanded model plus random effect for sire-by-herd management interaction ADSA-ASAS Joint Meeting 2004 (6)

  7. Data Analysis • 2 classifications investigated • Complete data set with various models • Herd Management Category • Estimation Methods • DO: Gibbsf90 to create posterior distribution • Median and SD among iterations • PR120: Probit.f90 threshold program • Mean and SD among iterations ADSA-ASAS Joint Meeting 2004 (7)

  8. Herd Management Categories • Herds classified by: • Level of synchronization use • Herd DFB standard deviation • Three categories: • STH- standing heat herds • Average 19% synch, 30.1 DFB SD • TAI- timed breeding herds • Average 81% synch, 13.7 DFB SD • MIXED- mixed management herds ADSA-ASAS Joint Meeting 2004 (8)

  9. TAI Herd: 1st Breedings ADSA-ASAS Joint Meeting 2004 (9)

  10. TAI Herd: 1st & 2nd Breedings ADSA-ASAS Joint Meeting 2004 (10)

  11. STH Herd: 1st Breedings ADSA-ASAS Joint Meeting 2004 (11)

  12. STH Herd: 1st & 2nd Breedings ADSA-ASAS Joint Meeting 2004 (12)

  13. Mixed Herd: 1st Breedings ADSA-ASAS Joint Meeting 2004 (13)

  14. Mixed Herd: 1st & 2nd Breedings ADSA-ASAS Joint Meeting 2004 (14)

  15. Herd Management Category:Median DO and Mean PR120 ADSA-ASAS Joint Meeting 2004 (15)

  16. Variance & Heritability: DO ADSA-ASAS Joint Meeting 2004 (16)

  17. Variance & Heritability: PR120 ADSA-ASAS Joint Meeting 2004 (17)

  18. Variance & Heritability: Data Subsets • Herd Management Category • Lower variance estimates for timed breeding herds • Larger sire and animal variance and h2 for standing heat herds • Variances for mixed herds were intermediate ADSA-ASAS Joint Meeting 2004 (18)

  19. Conclusions • Effect of synchronization on parameters • Reduced residual variance • Slight reduction in sire and residual variances • Negligible effect on heritability • Account for differences in protocol • Detection of estrus vs. timed breeding • Account for each protocol individually • Herd application of protocols • (Uniform vs. select) ADSA-ASAS Joint Meeting 2004 (19)

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