Status as of: 2015-09-22

Form GE

DESCRIPTION OF NATIONAL GENETIC EVALUATION SYSTEMS

Country (or countries)	United States of America	
Main trait group	Longevity [direct (single trait) and combined (multitrait) PL]	
Breed(s)	AYS (RDC), BSW, GUE, HOL (B&W, R&W, SIM), JER, MSH (RDC); all breeds and crossbred cows evaluated together in a multibreed AM	
Trait definition(s) and unit(s) of measurement	PL defined as time in milking herd before removal by voluntary culling, involuntary culling, or death; credits for each month in milk obtained from standard lactation curves and then summed across all lactations; diminishing credits within lactation give cows more credit for beginning a new lactation than for continuing to milk in previous lactation; cows get 8 months credit for 305-day first-lactation records, 10 months credit for second lactations, 10.2  months credit for third and later lactations, partial credits for shorter records, and extra credits for longer records	
Method of measuring and collecting data	Calving dates, disposal dates, reasons for disposal, and lactation lengths from data collected by Dairy Herd Information Affiliates; dead cows receive credit for months of production as stated above; live cows receive additional credit for predicted remaining life expectancy; prediction factors consider cow age and lactation stage; credits from >1 herd combined for cows that change herds; released PL combines information from direct longevity with evaluations from correlated traits	
Time period for data inclusion	First calvings from 1960 and later; pedigree from birth years 1950 and later; cows must be born at least 3 years prior to evaluation to be included	
Age groups (e.g. parities) included	All parities included	
Other criteria (data edits) for inclusion of records	Valid sire identification required with first-lactation records	
Criteria for extension of records (if applicable)	Records extended for cows still alive, sold for dairy purposes, or in herds that discontinued testing; cows sold for dairy purposes or in herds that discontinued testing receive extended records if they had opportunity to reach 3 years of age or otherwise have records discarded	
Sire categories	All sires (AI and NS) evaluated together	
Environmental effects, pre-adjustments 	Genetic variance in censored and uncensored management groups equalized by pre-adjusting censored data using expansion factors	
Method (model) of genetic evaluation	ST BLUP AM; records from censored management groups receive less weight than those from uncensored groups	
Environmental effects3 in the genetic evaluation model	Management group [flexible based on herd of first lactation and birth date (and registry status for HOL)] (F), regression on inbreeding (F), regression on general heterosis (F), herd × sire interaction (R); model produces PTA adjusted to 0 inbreeding, but released PTA includes regression coefficient multiplied by expected future inbreeding and coefficient of heterosis when mated to purebred as a post-processing step 	
Adjustment for heterogeneous variance in evaluation model	None	
Use of genetic groups and relationships	Unknown parents grouped by birth year, breed, and, for HOL, separately for U.S. and foreign animals; unknown sires and dams of cows grouped separately, but unknown parents of bulls in a combined group; relationship matrix accounts for effects of inbreeding on Mendelian sampling variance	
Blending of foreign/Interbull information in evaluation	Direct longevity for foreign bulls combined with PTA for other traits with same MT procedures used for domestic bulls	
Genetic parameters in the evaluation	See Appendix LO for h2 and genetic variance estimates; herd × sire interaction, 0.05; after direct longevity evaluation, information from 11 other traits and composites combined by selection index theory to increase PL REL based on genetic correlations with PL of 0.10 for milk yield, 0.15 for fat yield, 0.13 for protein yield, −0.45 for SCS, 0.64 for daughter pregnancy rate, 0.62 for cow conception rate, 0.32 for heifer conception rate, 0.40 for calving ability, 0.18 for udder composite, 0.14 for feet/legs composite, and −0.27 for size composite; selection index procedures use PTAs, parent averages (PAs), and PTA and PA RELs for the 12 traits and are applied to both bulls and cows in age order so that improved PL evaluations of parents are transferred to progeny	
System validation	Direct PL obtained with same AM programs used for yield; combined PL programs produced evaluations similar to multitrait, across-country evaluations when tested on international yield data; trend validation methods 2 and 3 applied separately for each breed	
Expression of genetic evaluations	PTA, months; all-breed PTAs adjusted to within-breed bases as within-breed PTA = (all-breed PTA – breed mean)	
Definition of genetic reference base
Next base change	Cows born in 2010 (stepwise, 5 years)

December 2019 (when base will be cows born in 2015)	
Calculation of reliability	Daughter with opportunity to reach 8 years of age considered a completed observation and gets 1 daughter equivalent (DE); cows with less opportunity get fewer DE regardless of whether they are culled or alive; DEs are 0.22 at 36 months of age, 0.53 at 48 months, 0.75 at 60 months, 0.89 at 72 months, and 0.95 at 84 months; those DEs combined with DE from parent average to calculate direct REL and then DEs from other traits increase combined REL	
Criteria for official publication of evaluations	All bulls evaluated for milk yield by USA or Interbull have official PL evaluations; Interbull longevity evaluations used if bull has foreign daughters or Interbull REL is higher than REL for ST domestic longevity evaluation	
Number of evaluations/ publications per year	3 (April, August, December)	
Use in total merit index4	PL receives 22% of total emphasis in lifetime net merit dollars (NM$, all breeds) and 14% of total emphasis in Total-Performance Index (TPI, HOL)	
Anticipated changes in the near future	None	
Key reference on methodology applied	VanRaden, P.M., and E.J.H. Klaaskate. 1993. Genetic evaluation of length of productive life including predicted longevity of live cows. J. Dairy Sci. 76:2758–2764.
VanRaden, P.M. 2001. Methods to combine estimated breeding values obtained from separate sources. J. Dairy Sci. 84(E-Suppl.):E47–E55.
VanRaden, P.M., C.M.B. Dematawewa, R.E. Pearson, and M.E. Tooker. 2006. Productive life including all lactations and longer lactations with diminishing credits. J. Dairy Sci. 89:3213–3220.
VanRaden, P.M., M.E. Tooker, J.B. Cole, G.R. Wiggans, and J.H. Megonigal, Jr. 2007. Genetic evaluations for mixed-breed populations. J. Dairy Sci. 90:2434–2441.
VanRaden, P.M., M.E. Tooker, J.R. Wright, C. Sun, and J.L. Hutchison. 2014. Comparison of single-trait to multi-trait national evaluations for yield, health, and fertility traits. J. Dairy Sci. (in press).	
Key organisation: name, address, phone, fax, e-mail, web site	Evaluation calculation and distribution:
Council on Dairy Cattle Breeding
One Town Center
4201 Northview Drive,
Suite 302
Bowie, MD 20716
Ph: 240 334 7744
e-mail: joao.durr@cdcb.us
web site: https://www.cdcb.us

Evaluation methodology:
Animal Improvement Program
Animal Genomics and Improvement Laboratory
Agricultural Research Service, U.S. Dept. of Agriculture 
10300 Baltimore Ave.
Bldg. 005, Room 306, BARC-West 
Beltsville, Maryland 20705-2350, USA
voice: 301-504-8334; fax: 301-504-8092 
e-mail: aipl.inquiry@ars.usda.gov
web site: http://aipl.arsusda.gov	

 

Form GE	Appendix LO

Parameters for national genetic evaluations for longevity traits as provided to Interbull

Country (or countries):	United States of America	
Main trait group:	Longevity (PL)	
Breed(s):	AYS (RDC), BSW, GUE, HOL (B&W, R&W, SIM), JER, MSH (RDC)	

Trait	h2	Genetic
variance	Official proof
standardisation formulaa	
Direct Longevity	0.08	SD = 5.04		
Combined Longevity	0.08	SD = 5.04		
a Expressed as follows:
	StandEval = ((Eval − a)/b) × c + d, where a = mean of base adjustment, b = SD of base, c = SD of expression (include sign if scale is reversed), and d = base of expression.