2007 J.B. Cole Animal Improvement Programs Laboratory Agricultural Research Service, USDA, Beltsville, MD Genetic Evaluation of Calving Traits in US Holsteins

LSU 2007 – Animal Sciences Seminar (2) Cole 2007 Introduction  National evaluations were introduced for Holstein calving ease (CE) in August 2002 and for stillbirth (SB) in August  A calving ability index (CA$) which includes SB and calving ease (CE) was developed.  Relationships among calving traits and other diseases are being studied.

LSU 2007 – Animal Sciences Seminar (3) Cole 2007 Why the concern?  Calving difficulty and stillbirth are expensive (Dematawewa and Berger, 1997; Meyer et al., 2001)  There is concern that rates of dystocia and stillbirth are increasing  Lactations initiated with dystocia have higher risks for other diseases (Cole et al., unpublished data).

LSU 2007 – Animal Sciences Seminar (4) Cole 2007 How do the evaluations work?  Funded by the National Association of Animal Breeders  Data are collected from multiple sources: Pedigree from breed associations Calving data from DRPC  Evaluated using a sire-maternal grandsire threshold model

LSU 2007 – Animal Sciences Seminar (5) Cole 2007 Threshold model  Scores assumed to be observations on a continuous underlying scale  Thresholds relate scores to underlying scale: Allows for differences in amount of change between consecutive scores Observed scores Underlying scale

LSU 2007 – Animal Sciences Seminar (6) Cole 2007 Calving ease definition  Reported on a five-point scale: 1 = No problem 2 = Slight problem 3 = Needed assistance 4 = Considerable force 5 = Extreme difficulty  Scores of 4 and 5 are combined

LSU 2007 – Animal Sciences Seminar (7) Cole 2007 Stillbirth definition  Reported on a three-point scale:  Scores of 2 and 3 are combined 1 = calf born alive, 2 = calf born dead, 3 = calf died within 48 h of parturition.

LSU 2007 – Animal Sciences Seminar (8) Cole 2007 Distribution of SB and CE Scores 7,484,309 29,320348,6775,348,0291,758,283 Total 96,087 1,27232,19638,92923, ,242 1,74037,851108,03759, ,029 3,35370,522375,203183, ,853 2,53749,858482,720203, ,809,09820,418158,2504,343,1401,287,290 1 Total3210 Calving Ease Score Stillbirth Score

LSU 2007 – Animal Sciences Seminar (9) Cole 2007 Stillbirth records by lactation

LSU 2007 – Animal Sciences Seminar (10) Cole 2007 Data and edits  7 million SB records were available for Holstein cows calving since 1980  Herds needed ≥10 calving records with SB scores of 2 or 3 for inclusion  Herd-years were required to include ≥20 records  Only single births were used (no twins)

LSU 2007 – Animal Sciences Seminar (11) Cole 2007 Sire-MGS threshold model  Implemented for calving ease (Aug 2002) and stillbirth (Aug 2006)  Sire effects allow for corrective matings in heifers to avoid large calves  MGS effects control against selection for small animals which would have difficulty calving

LSU 2007 – Animal Sciences Seminar (12) Cole 2007 Genetic evaluation model  A sire-maternal grandsire (MGS) threshold model was used: Fixed: year-season, parity-sex, sire and MGS birth year Random: herd-year, sire, MGS  (Co)variance components were estimated by Gibbs sampling Heritabilities are 3.0% (direct) and 6.5% (MGS)

LSU 2007 – Animal Sciences Seminar (13) Cole 2007 Trait definition  PTA are expressed as the expected percentage of stillbirths  Direct SB measures the effect of the calf itself  Maternal SB measures the effect of a particular cow (daughter)  A base of 8% was used for both traits:  Direct: bulls born 1996–2000  Maternal: bulls born 1991–1995

LSU 2007 – Animal Sciences Seminar (14) Cole 2007 Phenotypic trend for stillbirths

LSU 2007 – Animal Sciences Seminar (15) Cole 2007 Genetic trend for stillbirths

LSU 2007 – Animal Sciences Seminar (16) Cole 2007 Distribution of PTA

LSU 2007 – Animal Sciences Seminar (17) Cole 2007 Distribution of reliabilities

LSU 2007 – Animal Sciences Seminar (18) Cole 2007 Dystocia and stillbirth  Meyer et al. (2001) make a strong argument for the inclusion of dystocia in models for SB  Difficulty of interpretation - formidable educational challenge  Interbull trait harmonization - none of the March 2006 test run participants included dystocia in their models  Changes in sire and MGS solutions on the underlying scale between models were small

LSU 2007 – Animal Sciences Seminar (19) Cole 2007 Evaluation conclusions  Reliabilities for SB averaged 45% versus 60% for CE  Phenotypic and genetic trends from 1980 to 2005 were both small  An industry-wide effort is currently underway to improve recording of calf livability

LSU 2007 – Animal Sciences Seminar (20) Cole 2007 Index data  Same initial dataset as BV estimation  Calvings with unknown MGS were eliminated for VCE  Records with sire and MGS among the 2,600 most-frequently appearing bulls were selected  2,083,979 calving records from 5,765 herds and 33,304 herd-years

LSU 2007 – Animal Sciences Seminar (21) Cole 2007 Sampling  Six datasets of ~250,000 records each were created by randomly sampling herd codes without replacement  Datasets ranged from 239,192 to 286,794 observations, and all averaged 7% stillbirths  A common pedigree file was used to facilitate comparisons between sire and MGS solutions

LSU 2007 – Animal Sciences Seminar (22) Cole 2007 Heritabilities  Calving Ease (Direct)8.6%  Calving Ease (MGS)3.6%  Stillbirth (Direct)3.0%  Stillbirth (MGS)6.5%

LSU 2007 – Animal Sciences Seminar (23) Cole 2007 Genetic correlations among SB and CE Trait CESB DirectMaternalDirectMaternal CE Direct Maternal SB Direct Maternal1.00

LSU 2007 – Animal Sciences Seminar (24) Cole 2007 Economic assumptions  Newborn calf value  Expenses per difficult birth (CE ≥4) $450 for females $150 for males $75 labor and veterinary $100 reduced milk yield $75 reduced fertility and longevity 1.5% chance of cow death ($1800)

LSU 2007 – Animal Sciences Seminar (25) Cole 2007 Calving Ability index  CA$ has a genetic correlation of 0.85 with the combined direct and maternal CE values in 2003 NM$ and 0.77 with maternal CE in TPI  Calving traits receive 6% of the total emphasis in NM$ (August 2006 revision)

LSU 2007 – Animal Sciences Seminar (26) Cole 2007 Breeds other than Holstein  Brown Swiss economic values are −6 for SCE and −8 for DCE Separate SB evaluations are not available CE values include the correlated response in SB  Other breeds will be assigned CA$ of 0

LSU 2007 – Animal Sciences Seminar (27) Cole 2007 Health and calving traits  Health event data from on-farm computer systems  Events arranged in putative causal order by DIM at first occurrence  Path analysis to determine associations among disorders  Significant associations shown in following tables (P < 0.05)

LSU 2007 – Animal Sciences Seminar (28) Cole 2007 Health and dystocia DisorderDIMOdds Ratio Stillbirth139.0 Retained placenta13.8 Mastitis (0—30 d)62.3 Ketosis113.1 Metritis163.9 Reproductive322.3 Displaced abomasum292.2 Respiratory443.0

LSU 2007 – Animal Sciences Seminar (29) Cole 2007 Health and stillbirth DisorderDIMOdds Ratio Retained placenta12.8 Mastitis (0—30 d)62.4 Metritis162.1 Displaced abomasum302.3 Reproductive323.4 Digestive522.8

LSU 2007 – Animal Sciences Seminar (30) Cole 2007 Conclusions  A routine evaluation for stillbirth in US Holsteins was implemented in August 2006  Direct and maternal stillbirth were included in NM$ for Holsteins starting in August 2006  The US participates in routine Interbull evaluations that began in November 2006  Calving problems increase lifetime health care costs and decrease profitability

LSU 2007 – Animal Sciences Seminar (31) Cole 2007 Acknowledgments  Jeff Berger, Iowa State University  John Clay, Dairy Records Management Systems  Ignacy Misztal and Shogo Tsuruta, University of Georgia  National Association of Animal Breeders