ABSTRACT
Traditionally most of the emphasis of breeding in dairy cattle has been for milk and fat content. However, during the early 1980s, the emphasis shifted towards milk protein production, following the introduction of machines that could inexpensively assay protein content on thousands of samples. Genetic factors affecting fertility, health, growth and longevity in dairy cattle computed as the regression of the cows' estimated breeding values on their birthdates, for the entire milk-recorded population and the ratio of realized to expected gains are also given. A 'restricted index' is one in which the genetic change of some traits is fixed to a specific value. The simplest type of restriction proposed is to hold genetic change for a specific trait to zero. Genetic effects for animals that did not produce records, including males, are computed via genetic relationships between animals with and without records.
