| Country (or countries) |
USA |
| Main trait group |
Yield |
| Breed(s) |
AYS, BSW, GUE, JER, HOL (B&W and R&W), MSH |
| Trait definition(s) and unit(s) of measurement |
Milk (lb), fat and protein (lb, %) |
| Method of measuring and collecting data |
Collected by Dairy Herd Improvement Associations using ICAR approved methods. |
| Time period for data inclusion |
First calving 1960 and later plus pedigree from birth year 1950 and later. |
| Age groups (e.g. parities) included |
First five parities are included (a first lactation is required before later lactations can contribute to sire evaluations). |
| Other criteria (data edits) for inclusion of records |
Valid sire ID required. Lactations from cows >40 DIM and cows removed from the herd >15 DIM are included. TD by 90 DIM required. Owner sampler records are used from herds that meet identification, outlier, and bulk tank comparison limits. |
| Criteria for extension of records (if applicable) |
Records < 305 d are extended to 305 d using best prediction. |
| Sire categories |
AI and NS included. B&W and R&W HOL evaluated together. |
| Environmental effects, pre-adjustments |
Multiplicative adjustments for age at calving, month of calving, times milked per day (adjusted to twice daily milking), previous days open, and heterogeneous variance. The base age for mean and variance adjustments is 36-month-old second parity cows. Unequal variances across time and across herds are adjusted to the base calculated from standardized records of first lactation cows that calved in 2002. |
| Method (model) of genetic evaluation |
ST BLUP repeatability animal model. |
| Environmental effects in the genetic evaluation model |
Fixed: management group [flexible herd-year-season (2-12 months), includes registry status for HOL], parity x age, regression on inbreeding, Random: permanent environment, herd by sire interaction. This model produces PTA adjusted to 0 inbreeding, but published PTA include the regression multiplied by expected future inbreeding (EFI) as a post-processing step. |
| Adjustment for heterogeneous variance in evaluation model |
Pre-adjustments are applied. |
| Use of genetic groups and relationships |
Unknown parents grouped by year and, for Holsteins, separately for U.S. and Canadian animals. Sires and dams of cows grouped separately but parents of bulls combined. |
| Blending of foreign/Interbull information in evaluation |
Interbull sire evaluations and converted foreign dam evaluations from the previous evaluation with higher reliability than the current US evaluation are used to update parent averages and calculate evaluations. |
| Genetic parameters in the evaluation |
See PART 2 for heritability/genetic variance estimates; for multiple-trait genetic evaluations, provide genetic correlation estimates between traits separately |
| System validation |
Means and SD for all variables are calculated and examined overall. Means for new bulls, changes for high bulls, largest changes, and key statistics for recent AI bulls are checked. Genetic trends for all breeds are validated by methods 1, 2, and 3. |
| Expression of genetic evaluations. If standardised (e.g. RBV), give standardisation formula in the appendix |
PTA, lb and component % |
| Definition of genetic reference base |
Cows born in 2000, (stepwise, 5 year). |
| Calculation of reliability |
Daughter equivalents from parents and from progeny are summed by processing progeny from the youngest to oldest generation and then parents from oldest to youngest. Starting values for mate reliability are from the previous evaluation. |
| Criteria for official publication of evaluations |
At least 10 daughters with usable lactation record. Interbull evaluations are reported as official in the US if: they include data from an additional country; the US has no evaluation; or Interbull excludes US data and the Interbull evaluation has a higher reliability. |
| Number of evaluations / publications per year |
Four, in February, May, August, and November. |
| Use in total merit index |
Net merit dollars (NM$) = (4.81* protein) + (2.54*fat) + (26*productive life) - (166*SCS) - (12*size) + (33*udder) + (15* feet & legs)+ (17*Daughter Pregnancy Rate) - (5*service sire calving ease) - (5*daughter calving ease). Note: Type traits are composites, other traits are expressed as PTA, and weights are $/PTA unit. SCS and calving ease are deviations from breed average, i.e. not the published PTA which include breed average. Relative values of these traits are 33%, 22%, 11%, -9%, -3%, 7%, 4%, 7%, -2%, -2%, respectively. |
| Anticipated changes in the near future |
Accounting for differences in maturity by random regression on parity. |
| Key reference on methodology applied |
Wiggans, G.R., Misztal, I., and Van Vleck, L.D. 1988. Implementation of an animal model for genetic evaluation of dairy cattle in the United States. J. Dairy Sci. 71(Suppl. 2):54. VanRaden, P.M. and Wiggans, G.R. 1991. Derivation, calculation, and use of national animal model information. J. Dairy Sci. 74:2737. VanRaden, P.M., Wiggans, G.R., and Ernst, C.A. 1991. Expansion of projected lactation yield to stabilize genetic variance. J. Dairy Sci. 74:4344. Wiggans, G.R. and VanRaden, P.M. 1991. Method and effect of adjustment for heterogeneous variance. J. Dairy Sci. 74:4350. VanRaden, P.M. 1997. Lactation yields and accuracies computed from test day yields and (co)variances by best prediction. J. Dairy Sci. 80:3015. VanRaden, P.M. and L.A. Smith. 1999. Selection and mating considering expected inbreeding of future progeny. J. Dairy Sci. 82:2771. |
| Key organization: name, address, phone, fax, e-mail, web site |
United States Department of Agriculture |
Updated: This file last modified 02/28/24.
| Country (or countries): |
United States of America |
| Main trait group: |
Production (Yield) |
| Breed (repeat as necessary): |
AYS, GUE HOL, MSH, BSW, JER |
| Trait |
h2 |
Genetic SD |
| Milk yield |
Varies depending on herd variance. 0.25 to 0.35 |
[AYS] 1132 |
| Fat yield |
Varies depending on herd variance. 0.25 to 0.35 |
[AYS] 39 |
| Protein yield |
Varies depending on herd variance. 0.25 to 0.35 |
[AYS] 30 |
| Milk yield |
Varies depending on herd variance. 0.30 to 0.40 |
[BSW] 1317 |
| Fat yield |
Varies depending on herd variance. 0.30 to 0.40 |
[BSW] 52 |
| Protein yield |
Varies depending on herd variance. 0.30 to 0.40 |
[BSW] 40 |