Submitted to: Journal of Dairy Science
Publication Type: Abstract only
Publication Acceptance Date: 2/17/2006
Publication Date: 7/9/2006
Citation: Van Raden, P.M., Tooker, M.E. 2006. Revised estimates of lifetime net merit for dairy breeds and breed crosses [abstract]. Journal of Dairy Science. 89(Suppl. 1):246-247(abstr. 255). Interpretive Summary:
Technical Abstract: Dairy breeds and breed crosses were compared using updated net merit (NM), cheese merit (CM), and fluid merit (FM) formulas that include calving ease and daughter pregnancy rate (DPR). National data for milk, fat, protein, productive life, somatic cell score, and DPR were each evaluated using an all-breed animal model. New estimates of breed differences were compared to phenotypic breed differences and to previous estimates from studies that only included herds containing crossbred cows. Estimates of general heterosis from previous studies were used in the current research and not re-estimated. New estimates of breed effects were generally intermediate between the previous estimates and the phenotypic breed differences; all three estimates were similar. For calving ease, percentages of difficult births in first parity (%DBH) were estimated to be 7.9% for over 3.5 million Holstein (HO), 0.8% for 22,318 Jersey (JE), 4.7% for 5,909 Brown Swiss (BS), 3.3% for 1,418 Guernsey, 4.4% for 520 Ayrshire and 7.8% for 205 Milking Shorthorn. First generation crosses of JE x HO exceeded HO by $22 for NM and by $123 for CM, and BS x HO crosses exceeded HO by $32 for NM and by $102 for CM. All comparisons were at the genetic base of zero for each breed, and no crossbreds exceeded HO for FM. For later generations, backcrosses to HO are preferred for NM, whereas for CM, three-breed crosses may provide profit equal to HO backcrosses. Economic values were from 2003 and included relative emphasis of 33% on protein, 22% on fat, 11% on productive life, 9% against somatic cell score, 7% on daughter pregnancy rate, 7% on udder composite, 4% on feet and leg composite, 4% on calving ease, and 3% against body size composite. Economic values may need revision again during 2006 to account for a new definition of productive life, a new evaluation of calf livability, higher prices for butterfat relative to protein, and higher replacement heifer costs. Routine updates of economic values and breed differences can help producers to manage crossbreeding programs.