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United States Department of Agriculture

Agricultural Research Service

Title: Equity of Elite Cow Status Across States

Authors
item Powell, Rex
item Wiggans, George
item Norman, H

Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 9, 1998
Publication Date: N/A

Interpretive Summary: Concern had been expressed that a change in USDA-DHIA genetic evaluation methodology resulted in unfair designation among states of elite cows (cows with superior genetic merit based on an economic index). To determine if state representation for elite cows has been equitable, state percentages of U.S. cows with elite status were compared using evaluations of registered Holstein cows from 1990, 1991, and 1997. The number of elite cows for a state was highly related to the number of cows eligible for elite status. States with >1.0% of eligible cows designated elite had average economic indexes higher than the U.S. average of $44 but equal or slightly less variation than found nationally. Average economic index was associated with state percentage elite, but variation of the index was not related. However, index variation was important in explaining the percentage elite if average index also was considered. Differences in variation of lactation records across states or adjustments for those differences did not appear to cause inequity in designating elite status. Corresponding results for nonregistered cows, which are considered to be unbiased, supported findings for registered cows, which should allay industry concerns.

Technical Abstract: Cows with superior genetic merit based on the milk-fat-protein dollars index have been designated elite by USDA. To determine if state representation for elite cows has been equitable, state percentages of U.S. cows with elite status were compared using evaluations of registered Holstein cows from 1990, 1991, and 1997. Numbers and percentages of eligible cows and proportions designated elite were determined by state from May 1997 evaluations of 772,302 registered and 1,499,729 grade Holstein cows; means and standard deviations for milk-fat-protein dollars were computed. Correlations were computed among number of cows eligible for elite status, number of cows designated elite, percentage of eligible cows designated elite, and mean and standard deviation of milk-fat-protein dollars. Models to predict state percentage of elite cows from mean and standard deviation of milk-fat-protein dollars were examined. The number of elite cows for a state was highly related to the number of cows eligible for elite status. States with >1.0% of eligible cows designated elite had mean milk-fat-protein dollars higher than the U.S. mean of $44 but standard deviations equal to or slightly lower than the U.S. standard deviation of $71. Mean milk-fat-protein dollars was associated with state percentage elite, but variation of the index was not related. However, standard deviation of milk-fat-protein dollars was important in explaining the percentage elite if the model also contained the mean. Differences in variation of lactation records across states or adjustments for those differences did not appear to cause inequity in designating elite status. Corresponding results for grades supported findings for registered cows.

Last Modified: 10/25/2014
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