USDA Calving Ease and Stillbirth Evaluations


Country (or countries) United States of America
Main trait group Calving Ease (Service Sire and Daughter)
Stillbirth (Service Sire and Daughter)
Breed(s) HOL (B&W and R&W) (CE and SB), Brown Swiss (CE)
Trait definition(s) and unit(s) of measurement Daughter CE measures the ability of a particular cow (daughter) to calve easily. The CE evaluations are expressed as percent difficult births in primiparous heifers (%DBH), where difficult births are those scored as requiring considerable force or being extremely difficult (4 or 5 on a five point scale). Service Sire CE measures the tendency of calves from a particular service sire to be born more or less easily. Daughter SB measures the ability of a particular cow (daughter) to produce live calves. Service Sire SB measures the tendency of calves from a particular service sire to be stillborn more or less often. The SB evaluations are expressed as percent stillbirths in heifers (%SBH), where stillborn calves are those scored as dead at birth or born alive but died within 48 h of birth (2 or 3 on a three point scale)
Method of measuring and collecting data CE is scored by the owner on a scale of 1 to 5, 1 meaning no problems encountered or unobserved birth and 5 meaning extreme difficulty. SB is scored by the owner on a scale of 1 to 3, 1 meaning the calf was born alive and was alive 48 h postpartum, 2 meaning the calf was born dead, and 3 indicating the calf was born alive but died within 48 h postpartum. SB scores of 2 and 3 are combined into a single category for evaluation. In recent years, scores are reported almost entirely through the milk recording system.
Time period for data inclusion Calving dates since January 1, 1980.
Age groups (e.g. parities) included All parities.
Other criteria (data edits) for inclusion of records No multiple births. Sire age > 18 months and less than 18 years at time of calving. The maximum age of MGS at birth of dam also is 18 years. For Brown Swiss and Brown Swiss/Holstein crossbreds, no herds with a single calving record and no herds with only difficult CE scores. For CE, data from herd years with abnormal distributions of scores are excluded (about 3% of data) based on a goodness of fit statistic for the multinomial score distribution. For SB, herds must have at least 10 reported calf deaths in the database.
Criteria for extension of records (if applicable) None.
Sire categories All bulls are evaluated together.
Environmental effects, pre-adjustments None.
Method (model) of genetic evaluation Single-trait threshold sire-maternal grandsire (MGS) model. CE and SB are evaluated separately.
Environmental effects in the genetic evaluation model Random herd-year, fixed year-season, parity-sex, sire/mgs birth year group, MGS breed (CE only).
Adjustment for heterogeneous variance in evaluation model None.
Use of genetic groups and relationships Inverse of relationship matrix calculated using sire and MGS, birth year of sire and MGS effects.
Blending of foreign/Interbull information in evaluation None.
Genetic parameters in the evaluation CE: Varsire= 0.022, VarMGS= 0.016, Covsire-MGS= 0.009
SB: Varsire= 0.008, VarMGS= 0.018, Covsire-MGS= 0.004
System validation Means and SD for all variables are calculated and examined overall, as well as for each batch of incoming data (twice annually). Means for new bulls, changes for high bulls, largest changes, and key statistics for recent AI bulls are checked.
Expression of genetic evaluations. If standardised (e.g. RBV), give standardisation formula in the appendix DBH% - percent difficult births (score 4 & 5) observed in first calf heifers. SB% - percent stillbirths (score 2 & 3) observed over all parities. Values from underlying scales are reported to Interbull.
Definition of genetic reference baseNext base change For direct CE the base is bulls born in 2000. For maternal CE, it is bulls born in 1995. Separate bases are used for BSW and HOL bulls. For direct SB the base is bulls born between 1996 and 2000. For maternal SB, it is bulls born between 1991 and 1995. Next base change will be in 2010.
Calculation of reliability Approximated by inverse of diagonal element of coefficient matrix.
Criteria for official publication of evaluations AI bulls from studs supporting the program.
Number of evaluations / publications per year Two. February and August.
Use in total merit index 6% of the total emphasis for Net Merit will be placed on calving traits as follows: service sire CE – 1.26%, daughter CE – 0.95%, service sire SB – 1.26%, and daughter SB – 2.52%.
Anticipated changes in the near future  
Key reference on methodology applied
  • Cole, J.B., Wiggans, G.R., and VanRaden, P.M. 2006. Genetic evaluation of stillbirth in United States Holsteins using a sire-maternal grandsire threshold model. Proc. 8th World Congr. Genet. Appl. Livest. Prod. (Submitted)
  • Cole, J.B., Wiggans, G.R., VanRaden, P.M., and Miller, R.H. 2006. Stillbirth (co)variance components for a sire-maternal grandsire threshold model. J. Dairy Sci. (Submitted)
  • Cole, J.B., Goodling, Jr., R.C., Wiggans, G.R., and VanRaden, P.M. 2005. Genetic evaluation of calving ease for Brown Swiss, Jersey, and Holstein bulls from purebred and crossbred calvings. J. Dairy Sci. 88(4):1529-1539.
  • Van Tassell, C.P. and Wiggans, G.R. Enhancing quality of dystocia data by integration into a national dairy cattle production database. Proc. 7th World Congr. Genet. Appl. Livest. Prod. 32:557-560. Montpellier, France, Aug. 19-23, 2002.
  • Van Tassell, C.P., Wiggans, G.R., and Misztal, I. 2003. Implementation of a sire-maternal grandsire model for evaluation of calving ease in the US. J. Dairy Sci. 86(10):3366-3373.
  • Wiggans, G.R., Misztal, I., Van Tassell, C.P. 2003. Calving ease (co)variance components for a sire-maternal grandsire evaluation model.J. Dairy Sci. 86(5):1845-1848.
  • Wiggans, G.R., Van Tassell, C.P., Philpot, J.C., and Misztal, I. Comparison of dystocia evaluations from sire and sire-maternal grandsire threshold models. Proc. 7th World Congr. Genet. Appl. Livest. Prod. 32:561-564. Montpellier, France, Aug. 19-23, 2002.
Key organization: name, address, phone, fax, e-mail, web site Animal Improvement Programs Laboratory
USDA, Agricultural Research Service
Building 005, Room 306, BARC-West
10300 Baltimore Avenue Beltsville, Maryland 20705-2350
U.S.A.
Tel: 301-504-8334 Fax: 301-504-8092
E-mail: wiggans@aipl.arsusda.gov
Web site: http://aipl.arsusda.gov/

Updated: Aug 30 2006.

Genetic Parameters for Calving Ease

Country (or countries):

United States of America

Main trait group:

Calving traits

Breed(s):

BSW, HOL (B&W and R&W)

Trait

h2

Genetic variance

Official proof standardization formulaa

Direct calving ease

0.086

    

Maternal calving ease

0.048

    

Direct stillbirth

0.030

    

Maternal stillbirth

0.065

    
aExpressed as follows:
StandEval=((eval-a)/b)*c+d where a=mean of the base adjustment, b=standard deviation of the base, c=standard deviation of expression (include sign if scale is reversed), and d=base of expression.