Madelyn Womack

Effects of Types and Levels of Carbohydrates and Proteins on Carcass Composition of Adult Rats

Summary To study the interrelationships among dietary carbohydrates and proteins upon the production of body fat and protein, 12 groups of young adult male rats (200 days old) were fed, for 14 weeks, purified diets with sucrose and 1, 3, or 6% nitrogen from lactalbumin or wheat gluten, or corresponding diets containing cornstarch. Sucrose-fed rats ate more and gained significantly more weight and fat than cornstarch-fed rats only when fed the two higher levels of protein. After adjustment of the data to take into account differences in initial body weight and calorie intake, fat gains were still significantly higher in sucrose-fed animals. More efficient utilization of protein in cornstarch-fed rats was indicated but only at the 1% level of nitrogen. The data indicated that changes in body composition of adult rats are dependent to a larger extent upon specific combinations of nutrients than upon weight changes and calorie intakes.

Amino Acid Feeding Studies Effects of Various Nonessential Nitrogen Sources and of Added Water

Summary Young male rats fed equal, restricted amounts of diets containing low but presumably adequate levels of essential L‐amino acids made equally efficient use of the nitrogen of glutamic acid, aspartic acid or a mixture of 4 other nonessential amino acids for nitrogen gains. The nitrogen of diammonium citrate was only 85% as well utilized as that of the other compounds. At the same restricted calorie intake, nitrogen was more efficiently used when water was added to a diet containing low levels of essential amino acid nitrogen and glutamic acid nitrogen. The response to added water was abolished when the amount of glutamic acid nitrogen was doubled.

Glutamine and Glutamic Acid as Sources of Supplemental Nitrogen for Adult Rats

Summary The utilization of α- and amide nitrogen as sources of supplemental nitrogen to reduce nitrogen losses in the adult rat was studied using the nitrogen balance technique. Although young rats have been shown to utilize amide less efficiently than α-amino nitrogen as a source of supplemental nitrogen for carcass nitrogen gains, adult rats utilized the two equally well. Level of calorie intake or nutritional state of the adult animals did not influence the results.