CHANGES IN USDA-DHIA GENETIC EVALUATIONS (JULY 1995)

Authors: Vanraden, Paul; Powell, Rex; Wiggans, George; Norman, H

Submitted to: AIPL Research Reports
Publication Type: Government Publication
Publication Acceptance Date: 7/19/1995
Publication Date: N/A
Citation: N/A

Interpretive Summary: Changes in USDA-DHIA genetic evaluations in July 1995 were documented so that the dairy industry could make most effective use of information that incorporates improvements in methodology. Productive life (PL) and somatic cell score (SCS) evaluations and net merit indexes became available for the first time for cows. Currently, only cows older than 3 years and with usable data for both PL and SCS receive a net merit index. Mean reliabilities of evaluations for cows were about 30% for PL, 35% for SCS, 40% for net merit, and 45% for milk yield. Evaluations for yield traits were released for all cows with records and born in the last 15 years. Evaluations for cows born 16-20 years ago also were distributed if they had evaluated offspring. The International Bull Evaluation Service (INTERBULL) will release international evaluations in August 1995; these will replace current converted evaluations for European Holstein bulls. Although evaluations released by European countries between August and January will not be considered official by USDA, INTERBULL conversion equations may be used unofficially to obtain updates provided that European bases and models remain unchanged. Canadian evaluations were obtained for dams of U.S. bulls and incorporated into their sons' evaluations. Canadian evaluations were used if they had at least 5% more information than the U.S. evaluations. Reliabilities of evaluations were improved, and evaluations were adjusted when Canadian dam data were incorporated. Understanding by dairy producers of improvements in genetic evaluations will aid them in identifying the best animals to breed to achieve their selection goals. Larger profits are expected from selecting cows for net merit than from selection on yield traits alone.

Technical Abstract: Changes in USDA-DHIA genetic evaluations in July 1995 were documented. Productive life (PL) and somatic cell score (SCS) evaluations and net merit indexes became available for the first time for cows. Currently, only cows older than 3 years and with usable data for both PL and SCS will receive a net merit index. Linear type evaluations do not contribute to calculation of PL evaluations for cows. Mean reliabilities for cows are about 30% for PL, 35% for SCS, 40% for net merit, and 45% for milk yield. Evaluations for yield traits were sent for all cows with records and born in the last 15 years (previous limit was 10 years). Evaluations for cows born 16 to 20 years ago also were distributed if they had evaluated progeny. The International Bull Evaluation Service (INTERBULL) will release international evaluations in August 1995; these will replace current converted evaluations for European Holstein bulls. Although evaluations released by European countries between August and January will not be considered official by USDA, INTERBULL conversion equations may be used unofficially to obtain updates provided that European bases and models remain unchanged. Canadian evaluations from January 1995 were obtained for dams of U.S. bulls and incorporated into their sons' evaluations. Canadian evaluations were used if they had at least 5% more information than the U.S. evaluations. Reliabilities were improved and evaluations were adjusted (often upward) when Canadian dam data were incorporated. Increases in reliability for well-sampled bulls were often 2% or less. Bulls with reliabilities of only 40 to 60% for milk had increases of 5 to 10% in reliability when evaluations from Canada were converted and substituted for U.S. predictions of dam merit.