QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Purchase Article View Shopping Cart Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Forbes, E. B. Articles by French, C. E. Search for Related Content PubMed Articles by Forbes, E. B. Articles by French, C. E.

Further Experiments on the Relation of Fat to Economy of Food Utilization

II. By the Mature Albino Rat¹

Institute of Animal Nutrition, The Pennsylvania State College, State College

Respiration experiments were conducted by the open-circuit Haldane respiratory quotient procedure, with thirty-six mature albino rats as subjects, to investigate the energy expense of utilization (heat increment) of three complete diets differing in fat content and supplying ten vitamins in much larger quantities than in earlier experiments.

The heat increments were measured as the difference in heat production from maintenance and supermaintenance diets containing 2, 10 and 30% of fat, respectively, so compounded and fed as to supply equal quantities of gross energy, protein, and vitamins.

The fat content of the diets had little effect on nitrogen utilization, but with the supermaintenance food intake there was slight increase in urinary nitrogen and decrease in nitrogen retention in the order of the increasing fat content of the diets. There were slight decreases in metabolizable energy and larger decreases in heat production in the order of the increasing fat contents of the diets, the fat component, therefore, conferring economy of utilization of food energy.

The heat increments of the dietary supplements containing 2, 10 and 30% of fat, respectively, representing the use of food above maintenance, with voluntary activity excluded, were equivalent to 31, 26 and 16%, respectively, of their gross energy.

The decreasing energy expense of utilization of the isocaloric intake of the diets in the order of their increasing fat contents was due mainly to decreasing heat from the catabolism of carbohydrates. No fat was catabolized from the 2%-fat diet, while much heat was produced from fat in the 30%-fat diet.

Heat production from fat synthesis occurred in the three periods in which the carbohydrate intake was highest.

Manuscript received 10 June 1946.