Abstract
Our rats are generally requisitioned by bodyweight. It is imperative, therefore, that an efficient method be used for determining the weights of animals in a given location to fill order commitments. Given any beginning average weight at an age on or after 21 days this method predicts the average weight of animals in a cage for any future date within practical limits. It assumes that the growth curve may be adequately represented by linear segments. The method also accounts for the differing growth rates of light and heavy animals. In order to maintain current estimates of these growth rates, we take a small weekly sample of representative rats at 21 days of age. These animals are reweighed weekly to provide data for continual reestimation of the growth-rate parameters used for prediction.