Cow-Indexing Procedure and Culling Levels for Potential Dams of Dairy Bulls

A procedure to index dairy cows on milk production is described.First records of cows were compared to first records of contemporaries, and second and later records of cows to second and later contemporary records.The index combined this information with the proof of the cow's sire.Of 5,704 Guernsey cows, 144 had indices two or more standard deviations above the average index.Restrictions on the milk fat percentage of these "potential" dams of bulls caused the numbers to drop rapidly.Restrictions on type classification decreased numbers to a lesser degree.Mean indices suggested that cows classified "Excellent" received preferential treatment.