The Food Intake of Young Rats Held at Nearly Constant Body Weight by Restriction of the Dietary Protein

Abstract

Thirty-five male and thirty-two female albino rats (Wistar strain) were maintained for 15 weeks at body weight of about 50 gm. by regulated amounts of protein (yeast-wheat germ) intake. A diet otherwise adequate for normal nutrition was fed, including 2 drops of cod liver oil daily with basal diet ad libitum. The room was held at nearly constant temperature (26°C.). Under these conditions, the required (limited) intake of yeast-wheat germ mixture increased slightly during the first week (period of adjustment). Beginning with the second week, the consumption decreased steadily from an average of over 3.1 gm. per rat to about 2.7 gm. in the sixth week, remaining nearly stationary thereafter. The corresponding voluntary intake of basal diet ran closely parallel to the limited protein intake, the average weight of yeast-wheat germ remaining nearly constant at about 11% of the total diet (including accessories). The calories of the total diet appeared slightly above the energy requirement for maintenance. The data indicate a slight but probably significant sex difference in the food intake of the rats under these conditions. The male rat apparently requires relatively less protein (yeast-wheat germ) for maintenance, and shows likewise a relatively smaller intake of the basal and total diet.