2002 George R. Wiggans and Curt P. Van Tassell Animal Improvement Programs Laboratory Agricultural Research Service, USDA, Beltsville, MD USDA Genetic Evaluations for Calving Ease

NAAB IMC (2) G.R. Wiggans 2002 Calving Ease Evaluations  Objective:  Reduce calving problems during calving (especially first calvings)  Procedure:  Collect reports on calving difficulty  Calculate sire evaluations

NAAB IMC (3) G.R. Wiggans 2002 Frequency of Calving Difficulty Lactation Calving Ease Score 1 st 2 nd 3 rd 1 – No Problem 63%80%81% 2 – Slight Problem 14%10%9% 3 – Needed Assistance 14%7% 4 – Considerable Force 5%2% 5 – Extreme Difficulty 3%1%

NAAB IMC (4) G.R. Wiggans 2002 History 1977 – NAAB-sponsored evaluations within AI organizations 1980 – NAAB-sponsored evaluations across AI organizations 1988 – Ordered categorical threshold model 1990 – Semi-annual evaluations 1999 – Processing moved from Iowa State University to USDA (November) 2002 – Sire-maternal grandsire (MGS) model

NAAB IMC (5) G.R. Wiggans 2002 Sire – MGS Project Improved Data  Enhanced detection of duplicate calving reports  Use of animal key to deal with identification changes  Database maintenance to allow easy update and access  Access to pedigree from production evaluations to increase data accuracy and provide missing MGS information

NAAB IMC (6) G.R. Wiggans 2002 Sire – MGS Project  Improved Model  MGS effect added  Evaluations of bulls as service sires improved by partially accounting for mates  Maternal effect on calving difficulty included in MGS effect

NAAB IMC (7) G.R. Wiggans 2002 Data  Over 11 million calving reports since 1980  Pedigrees matched to production evaluation pedigree database  2.5 million pedigree records for cows without unique national identification also included  Improved edits yield 10.5 million unique calving reports

NAAB IMC (8) G.R. Wiggans 2002 Additional Data Requirements  Single birth  Dam and sire of Holstein or Red & White breed  Sire age >18 mo and <15 yr at birth of calf  Birth date of Jan. 1, 1980, or later 10,195,097 records extracted

NAAB IMC (9) G.R. Wiggans 2002 Threshold model  Scores assumed to be observations on a continuous underlying scale  Thresholds estimated to relate observed scores to underlying scale Procedure allows for differences in amount of change between consecutive scores Underlying scale

NAAB IMC (10) G.R. Wiggans 2002 Model Definition MODEL: y = HY + YS + PS + Y s + Y m + s + m + e y=CE score HY=random herd-year YS=fixed year-season PS=fixed parity-gender YsYs =fixed birth year of sire YmYm =fixed birth year of MGS s=Sire m=MGS e=unexplained residual

NAAB IMC (11) G.R. Wiggans 2002 Sire-MGS Model Statistics Range Effect LevelsMinimumMaximum Herd-year 204, Year-season Parity-gender Sire birth year MGS birth year Sire 120, MGS 120,

NAAB IMC (12) G.R. Wiggans 2002 VC Estimates, Heritabilities, and Correlation of Traits (Co)VarianceSire0.022 MGS0.016 Sire-MGS0.009 Heritability (%)Direct8.6 Maternal4.8 CorrelationDirect-Maternal-0.12

NAAB IMC (13) G.R. Wiggans 2002 Presentation of Evaluations  Evaluations converted to expected percentage of difficult (scored 4 or 5) births for heifers (%DBH)  Most frequent %DBH was 8%  Genetic Base  Daughter CE – MGS born in 1990  Service sire CE - sires born in 1995  %DBH for MGS relatively constant  %DBH for sires increasing

NAAB IMC (14) G.R. Wiggans 2002 Calving Ease Trends

NAAB IMC (15) G.R. Wiggans 2002 Status of Evaluation System  Sire-MGS evaluations for CE released in August 2002  Web queries to display CE data available to participants  Daughter CE may be included in future index calculations