2002 ADSA 2002 (HDN-1) H.D. NORMAN* ( ), R.H. MILLER, P.M. V AN RADEN, and J.R. WRIGHT Animal Improvement Programs Laboratory Agricultural Research Service, USDA Beltsville, MD J.S. CLAY North Carolina State University, Raleigh, NC ‑ 3435 Genetic relationships among fertility traits of Holsteins and Jerseys (abstract 351)

2002 ADSA 2002 (HDN-2) Why evaluate fertility traits?  Low heritability estimates but large phenotypic variation  High economic value  Decline in reproductive performance  Antagonistic relationship between milk yield and reproductive traits

2002 ADSA 2002 (HDN-3) Objectives  Estimate genetic relationships among fertility traits  Determine which reproductive traits have greatest potential use for evaluating daughter fertility of bulls

2002 ADSA 2002 (HDN-4) Management factors  Voluntary waiting period between calving and first breeding  Use of bST  Designed reproductive programs

2002 ADSA 2002 (HDN-5) Data processing factors  Computer program differences among dairy records processing centers  DHI reproduction options  Calving interval estimation without subsequent calving date

2002 ADSA 2002 (HDN-6) Data  2.2 million Holstein and 0.2 million Jersey breeding records from 1995 through 2000 that included:  Yield (milk, fat, protein) for first 3 test days  Identification (service sire, cow, sire, dam)  DIM at each service  Parity  DHI herds with records processed by:  AgriTech Analytics  AgSource Cooperative Sources  Dairy Records Management Systems  Pennsylvania DHI Association

2002 ADSA 2002 (HDN-7) Data restrictions  <150 DIM at third test day  Daily milk yield between 4.5 and 109 kg  Test-day component percentage between 2.0 and 8.0  Fat and protein percentages reported for at least 2 of first 3 test days

2002 ADSA 2002 (HDN-8) Fertility traits  Days from calving to first service  Days from calving to last reported service (days open)  Nonreturn to first service within 70 d (nonreturn rate)  Number of services

2002 ADSA 2002 (HDN-9) Fertility restrictions  Successful breeding if cow not reported in estrus or rebred within 70 d  Breedings excluded:  Virgin heifers  365 DIM  Cows that left herd <70 d after first service  Subsequent breedings within 4 d  Non-AI first services  Herd:  >9 AI matings annually  >9 or <90% for annual mean for nonreturn rate

2002 ADSA 2002 (HDN-10) Means TraitHolsteinJersey Days to first service9083 Days open Nonreturn rate (%)5557 Number of services2.12.0

2002 ADSA 2002 (HDN-11) Analysis  Fertility traits adjusted for:  Parity (fixed; 1, 2, … 5, 5+)  Age deviation within parity (linear regression)  2 highest test-day yields (linear regression):  Milk  Fat  Protein  Lactation stage at first service (nonreturn rate and number of services only)

2002 ADSA 2002 (HDN-12) Analysis (continued)  Heritabilities and genetic correlations estimated with multitrait REML sire model:  Observations from 1998 to 2000  3447 Holstein bulls with  40 daughters  2602 Jersey bulls

2002 ADSA 2002 (HDN-13) Heritability estimates (%) TraitHolsteinJersey Days to first service74 Days open43 Nonreturn rate11 Number of services22

2002 ADSA 2002 (HDN-14) Genetic correlations TraitD1DONRNS D DO – NR0.09– –0.88 NS – Legend: D1 = days to first service Holstein correlations DO = days open Jersey correlations NR = nonreturn rate NS = number of services

2002 ADSA 2002 (HDN-15) Phenotypic correlations TraitD1DONRNS D DO – NR0.00– –0.57 NS – Legend: D1 = days to first service Holstein correlations DO = days open Jersey correlations NR = nonreturn rate NS = number of services

2002 ADSA 2002 (HDN-16)  Days open has higher heritability than nonreturn rate  Days open has moderate to high genetic correlation with days to first service and number of services  Days open appears to be best single measure among fertility traits examined for genetic evaluation of cow fertility Conclusions