A simple procedure for obtaining approximate interim cow solutions from an animal model.

The computational costs required for solving the equations for an individual animal mixed model can be considerable. More frequent evaluations would benefit dairy producers, allowing them to make breeding and management decisions earlier. A procedure was developed to immediately obtain approximate estimates of cow breeding value as soon as new information becomes available. Only solutions for cows with records in progress are updated. The algorithm is based on solving a system of two equations and can be applied by producers. The method corrects for changes in estimated production of the current record of a cow but assumes that the effects of changes in evaluations of other animals related to this cow on the evaluation of the cow in question are negligible. Herd-year-season effects are not reestimated. The correlations between the updated cow evaluations based on animal model evaluations computed during May 1992, but using estimated production from November 1992, for records in progress and the animal model evaluations from November were .027 to .064 higher than the correlations between the May and November evaluations for production of milk, fat, and protein. Although gains are slight, the cost application of the algorithm is insignificant.