2002 Paul VanRaden, Ashley Sanders, Melvin Tooker, Bob Miller, and Duane Norman Animal Improvement Programs Laboratory Agricultural Research Service, USDA, Beltsville, MD Genetic Evaluation of Cow Fertility expressed as Pregnancy Rate
S-284, NAAB DSEC 2002 (2) P.M. VanRaden 2002 Factors Affecting Fertility Service bull Sperm motility, abnormality, etc. measured by AI companies ERCR ratings from Environment and genes of cow Interaction of bull and cow Lethal recessives, inbreeding
S-284, NAAB DSEC 2002 (3) P.M. VanRaden 2002 Pregnancy Rate Rate that cows become pregnant Can be derived from days open Non-linear: 21 / (DO – VWP + 11) Linear approx: (233 – DO) / 4 Advantages over days open Positive numbers are desirable Earlier measure of herd fertility
S-284, NAAB DSEC 2002 (4) P.M. VanRaden 2002 ≤ 50 ≥ 250 Distribution of Days Open Holstein Calvings Cows culled for reproductive reasons
S-284, NAAB DSEC 2002 (5) P.M. VanRaden 2002 Average breed effects across regions and time by calving month
S-284, NAAB DSEC 2002 (6) P.M. VanRaden 2002 Regional effects for Holsteins calving since 1997
S-284, NAAB DSEC 2002 (7) P.M. VanRaden 2002 Parameter Estimates Multi-trait REML analysis of first lactations Heritability of DO3.7% Correlations with DOPhenotypicGenetic Milk Fat Protein SCS PL
S-284, NAAB DSEC 2002 (8) P.M. VanRaden 2002 Pregnancy Rate Evaluation Lactations 1-5 beginning with 1960 Data sources Reported DO confirmed with next calving – Exclude most recent 9 months Reported DO if no next calving – Exclude most recent 9 months Calving interval – 280 days if no reported DO – Exclude most recent 18 months Assigned DO = 250 if sold for infertility
S-284, NAAB DSEC 2002 (9) P.M. VanRaden 2002 Evaluation Methods BLUP Animal Model Same programs used for yield, PL, SCS Convert to preg rate = (233 – DO) / 4 Adjust for heterogeneous variance Parameter estimates used: Heritability = 4% Repeatability = 11% Sire-by-herd interaction = 1%
S-284, NAAB DSEC 2002 (10) P.M. VanRaden 2002 Evaluation Test Run Holstein data from Aug 2002 evaluation 40 million lactations 16 million cows Statistics for recent, well-sampled bulls Born Milk REL > 80% (mean = 87%) 4215 Holstein bulls 314 Jersey bulls Example evaluations for older sires
S-284, NAAB DSEC 2002 (11) P.M. VanRaden 2002 Recent Bull Evaluations HolsteinJersey Pregnancy Rate PTA range -4.8 to to +1.5 REL mean 59%57% PTA correlations PL SCS Milk-.22 Fat Protein
S-284, NAAB DSEC 2002 (12) P.M. VanRaden 2002 Older Bull Evaluations RELDODPRPLNM$ Duster Bellwood Mandel Luke Mountain Mascot
S-284, NAAB DSEC 2002 (13) P.M. VanRaden 2002 Pregnancy Rate Genetic Trend
S-284, NAAB DSEC 2002 (14) P.M. VanRaden 2002 Phenotypic Trend – Holstein DO 5 th 4 th 3 rd 2 nd 1 st Lactation
S-284, NAAB DSEC 2002 (15) P.M. VanRaden 2002 Conclusions Daughter Pregnancy Rate has low heritability (~4%) but high genetic correlation with Productive Life (>.5) Official evaluations for DPR planned for February 2003 Selection on PL has greatly reduced the decline in cow fertility Economic value not yet determined
S-284, NAAB DSEC 2002 (16) P.M. VanRaden 2002 Acknowledgments All DHIA herds and processing centers contributed data George Wiggans and Lillian Bacheller improved the fertility database John Clay suggested expressing cow fertility as pregnancy rate