The Composition of Milk from Stock Rats and an Apparatus for Milking Small Laboratory Animals

Abstract

More than 600 cc. of milk from stock rats, obtained by means of a micro-milking device, have been analyzed. Milk solids are approximately three times as concentrated as in cow's milk. Compared to human and cow's milk, rat milk is low in carbohydrate, and high in protein and fat. The average composition of rat milk obtained at various stages of lactation is: total solids, 31.7%; protein, 11.8%; fat, 14.8%; carbohydrate, 2.8%; and ash, 1.5%. Studies on the distribution of nitrogen in the total protein, on the constants of the extracted butter fat, and on the composition of the ash of rat's milk are reported. The buffer values of rat and guinea pig milk have been determined, and are compared with similar values for cow's milk and human milk.