Paul VanRaden Animal Improvement Programs Laboratory Beltsville, MD, USA Inbreeding Adjustments and Effect on Genetic Trend Estimates
INTERBULL ANNUAL MEETING 2005 (2)P.M. VanRaden Adjustments Introduced Feb 2005 Inbreeding depression: Remove by regression in animal model Then include expected future inbreeding EFI =.5 mean relationship to current cows Parity variance Heterogeneous variance refinement September 2004 test run included both
INTERBULL ANNUAL MEETING 2005 (3)P.M. VanRaden Inbreeding Adjustments VanRaden and Smith 1999 JDS 82:2771 Subtract regression (b) from y YD 0 = y - m - p - c - b (F cow ) DYD 0 and PTA 0 reflect 0 inbreeding Add expected future inbreeding PTA EFI = PTA 0 + b (EFI - EFI base ) PA EFI = PA 0 + b (EFI - EFI base ) DYD EFI = DYD 0 + b (EFI - EFI base )
INTERBULL ANNUAL MEETING 2005 (4)P.M. VanRaden Effects of Inbreeding Adjustment Genetic evaluations of recent Holsteins Corr (PTA, PTA EFI ) =.998 for bulls Corr (PTA, PTA EFI ) =.993 for cows Genetic correlations of USA with other countries declined by.01 (Sep 1999 test run) Genetic trend Yield trends were 6% lower for PTA EFI Fertility, longevity trends 14-25% lower
INTERBULL ANNUAL MEETING 2005 (5)P.M. VanRaden Changes in Trends and Trend Tests from Inbreeding Adjustments Trait Trend Change SD/yr Trend Test Differences Test 1Test 2Test 3 Protein Fat SCS PL-.024N/A DPR
INTERBULL ANNUAL MEETING 2005 (6)P.M. VanRaden Parity Variance Adjustments Trend test 1 was.014 (fail), now.008 (pass) for Jerseys. Holsteins were OK. Deviations for yield are multiplied by [ ] (parities 1-5) Genetic trend for protein decreased by.004 genetic SD / year (2% change) Corr (official, adjusted PTA) =.9998 for recent Holstein bulls
INTERBULL ANNUAL MEETING 2005 (7)P.M. VanRaden USA vs Non-USA Bull Trends Before (Aug) and After (Sep) Adjustments Genetic Trend (SD / yr) Ratio (Non- USA / USA) USA bullsNon-USA ScaleAugSepAugSepAugSep CAN DEU FRA NLD USA
INTERBULL ANNUAL MEETING 2005 (8)P.M. VanRaden Effect on Top 100 Bulls Average number of USA bulls in top 100 across all 27 protein scales Increase from 24.5 to 25.3 (Holstein) Increase from 53.8 to 56.3 (Jersey) USA genetic trend Decreased 6% (Holstein) Decreased 9% (Jersey)
INTERBULL ANNUAL MEETING 2005 (9)P.M. VanRaden Conclusions Boichard et al (1995) stated that biased genetic trend “strongly disturbs international germplasm exchanges based on conversion formulas...” MACE is robust to trend bias Trend tests should not be required