A Comparison of Two Stock Rations for Albino Rats

Abstract

Data have been assembled from the breeding records of a colony of albino rats over a period of 15 years. The effects of two stock rations, our long-used supplemented calf meal diet and the Bills modification of the Steenbock stock diet, have been compared with respect to the percentage of litters cast and weaned and the weights of both mothers and young at three intervals during the lactation period. Lactation has been somewhat less satisfactory in recent years with each ration. With the first, a nursing mother has been able to maintain her weight until the young were weaned, regardless of the size of the litter. With the second, the mother lost weight throughout lactation, unless the litter was very small (3–6). The weaning weights of the young in each group varied with the number of young in a litter and with the position in the litter series.