The Effects of a Vitamin B12 Supplement, Vitamin B12 and Streptomycin on the Metabolism of the Rat

Abstract

The effects of a vitamin B₁₂ supplement, purified vitamin B₁₂, and streptomycin on the utilization of the food protein and energy of an all-plant protein ration were studied in growth and body balance experiments with growing albino rats as subjects. In a paired feeding experiment in which one animal of each pair received the basal ration supplemented with a crude vitamin B₁₂ mixture, feed consumption was severely limited by the animals on the unsupplemented ration and growth to a common predetermined weight required approximately twice as long as when the supplemented ration was fed ad libitum to a third group of animals. Efficiency of gains was of a much higher order on ad libitum feeding than on paired feeding, and the efficiency of gains was greater in the paired animals receiving the vitamin B₁₂ supplement. Body gain of energy was 29% greater in the supplemented pair-fed animals than in the unsupplemented animals, and heat production was 3.5% less. By feeding the two main constituents of the crude supplement used — vitamin B₁₂ and streptomycin — both singly and in combination, but in the same amounts as when the crude supplement was employed, it was found that streptomycin had little effect on growth; vitamin B₁₂ greatly improved growth and utilization of feed; and streptomycin and vitamin B₁₂ together were slightly better than vitamin B₁₂ alone, although no combination was quite as good as the crude supplement itself. In these studies the nitrogen utilization did not appear to be specifically affected by any of the supplements used. The more rapid and more efficient growth of the experimental animals receiving vitamin B₁₂ is attributed primarily to greatly increased intake of feed as compared to the intake when this supplement was not given.