By George Wiggans
Rules for exclusion of data have been revised. In August 2002, a floor and ceiling based on a predicted value were introduced. Now, some extreme tests that appear to be recording errors or extremely low are excluded instead of set to a floor or ceiling. As an extension of the rule for sick cows where the test day yield is excluded if it is less than 10 lb, test day yields less than 10 lb also are excluded for cows not coded as sick if the yield is less than half the average of the adjacent yields. This rule reduces the impact of differences in reporting of sickness. Yields that are more than 130 lb above predicted are excluded. A change was made for when there are only two tests. Instead of always comparing them with the herd average, the herd average comparison is made only if one would be considered abnormal based on the other. All lactations since 1997 were recalculated with these new rules for the May 2003 evaluation.