WERNER G. JAFFÉ
Instituto Nacional de Nutrición, Caracas, Venezuela
Received for publication October 29, 1955
Large sectors of the human populations live on a more of less exclusively vegetarian diet. This fact induced us several years ago to initiate studies on the effect of such a type of feeding on experimental animals kept under similar conditions for many generations. Preliminary experiments showed the existence of some factor (Jaffé, ’46), later identified as vitamin B12 (Jaffé, ’48) lacking in this kind of ration. Because vegetarian diets are low in this vitamin, it seemed interesting to conduct some long-range experiments on their effect on experimental animals. Moreover, an attempt has been made to determine the minimum vitamin B12 requirements for growth, reproduction and lactation of the rat under conditions of uniform intake during more than one generation.
The animals were descendants of the «Sprague Dawley» strain. All the rats of the experimental series were from a stock kept on a soybean oil meal-corn ration since 1948, while a control group was always fed a commercial stock diet. The animals were housed in screen bottom cages in a room without air conditioning. Large litters were always reduced to 6 within 48 hours after birth, weaned at 21 01′ 28 days of age and kept together in a common cage to permit brother and sister mating for the following generation. In special cases, the females of one litter were bred with males of another of the same experimental group. Pregnant females were weighed and put in single cages. Females were bred only once except in a few cases when they were bred a second time.
The composition of the experimental basal diet in parts by weight was as follows : soybean oil meal, 46; whole yellow corn meal, 46; USP Salt Mixture no. 2, 2; sesamo oil containing 0.2% of percomorphum oil and 0.2% of wheat germ oil, 5; and the following vitamins per kilogram of diet: thiamino hyclrochloricle, 3.0 mg; ribotlavin, 3.0 mg; pyricloxine hyclrochloricle, 2.0 mg; Ca-pantothenate, 2.0 mg; niacin, 20 mg; folic acid, 0.25 mg; biotin, 0.10 mg; p-amino benzoic acid, 250 mg; inositol, 100 mg; choline chloride, 1 gm.