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Article: Selection Responses for Clinical Mastitis and Protein Yield in Two Norwegian Dairy Cattle Selection Experiments
- Article from:
- Journal of Dairy Science
- Article date:
- September 1, 2003
- Author:
CopyrightCopyright American Dairy Science Association Sep 2003. Provided by ProQuest LLC. (Hide copyright information)
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ABSTRACT
Inferences from two dairy cattle selection experiments, in which sires were selected from external sources, were drawn by using an animal model to analyze data from the entire population. The first selection experiment was carried out in the period from 1978 to 1989 and included groups selected for high milk production (HMP) and low milk production (LMP). Each year, the highest ranking proven sires for milk production, from the most recent group of Norwegian Dairy Cattle (NRF) test bulls, were selected and mated to the cows in the HMP group. A group of sires with low milk production indices from progeny testing in 1978 and 1979 were used as sires in the LMP group during the entire ...