Diets containing AAF or ARF instead of RF were administered to RF-deficient mice and growth was followed, and after 9 days liver and kidneys were removed and weighed. No significant difference in growth was found between experimental and control (RF-deficient) groups. AAF significantly increased the weight percentage of liver to body weight, and the liver of some mice administered AAF or ARF had the appearance of fatty liver. In kidneys no difference in weight percentage and appearance was found between experimental and control group. The hair of mice administered ARF was nearly as clean as that of mice administered RF, although that of mice deficient in RF or ad-ministered AAF was dirty and had the appearance of being drenched. Mice administered HF per os or by subcutaneous injection were not distinguished from RF-deficient mice in growth, weight of liver and kidneys, and in appearance of hair.
Kinetic parameters of potassium metabolism were utilized for the estimation of the daily milk intake of the suckling rat. These parameters included the turnover rate of potassium as determined from the whole-body retention curve of 42K, the total potassium content as measured by means of atomic absorption spectrometry, and the potassium content of milk samples from the lactating dams. The daily intake of potassium was calculated using the whole-body potassium content, the turnover rate constant, and the assumption that the body is a single instantaneously mixing compartment for potassium. The daily milk intake of suckling rat was calculated from the daily potassium intake and the concentration of potassium in rat milk. The results showed that the daily milk intake varies from 1.6g of milk for a newborn rat to 6g for a 14 day-old suckling rat.
The effect of hydrochloride-free, casein-simulated amino acid mixture on growth and food intake in young rats was studied. Weight gain of rats fed a hydrochloride-free amino acid diet ad libitum was greater than that of rats fed an amino acid diet containing basic amino acids in hydro-chloride form due to an increase in food intake. A hydrochloride-free amino acid diet was, however, still considerably inferior to a casein diet in supporting growth. Addition of sodium bicarbonate to the amino acid diet containing amino acid hydrochloride had no effect on ratt growth.
The effects of protein and/or energy deficiency on 14C incorporation into body constituents and 14C output in expired air and urine were investigated in adult rats using 14C-Chlorella protein hydrolysate. Rats were given a protein-free diet (PFD) for 2 weeks and control rats were fed ad libitum or pair-fed with the PFD group on a 12% lactalbumin diet (LA and Pair-fed, respectively). On the 15th day, animals received 14C-Chlorella protein hydrolysate with 5g of their respective diet. One group of PFD animals was given tracer by stomach tube without food (PFD-fast). Normal control rats ate about twice as much diet as the PFD group. The respiratory 14C output in the PFD group was identical with those in the LA and Pair-fed groups and was less than that in the PFD-fast group, The rate of protein synthesis, provisionally expressed as relative specific radioactivity, was more in the PFD group than in the normal group in the liver and less than the latter in the muscle. The LA group retained less total radioactivity in the body than the Pair-fed or PFD group, indicating high capability to hold the body protein in protein deficiency. In addition, decreased conversion of amino acids to lipids and glycogen was observed in the PFD group. All these differences are interpreted as adaptations to protein shortage. On prolonged fasting (PFD-fast group), gluconeogenesis in the liver increased to provide energy, despite the protein deficiency. The relative importances of protein and energy for tissue protein synthesis are briefly discussed.
Changes in fatty acid patterns of lipids in serum and erythrocytes in-duced by dietary fats and in vitro incorporation of fatty acids into ery-throcyte membranes were investigated with pigs. On feeding various diets, it was found that fatty acid composition of serum and erythrocytes could be modified and altered toward the fatty acid pattern of the diet. In vitro, the incorporation of labeled fatty acids into erythrocyte mem-branes was accelerated by the addition of cofactors such as lysolecithin, CoA and ATP. Dietary fats also had certain effects on the incorporation of fatty acids into erythrocyte membranes. Erythrocytes, collected from the blood of pigs fed corn oil, incorporated and also released more labeled linoleate than those of pigs fed hydrogenated soybean oil. Palmitic acid was more slowly incorporated into erythrocyte membranes than linoleic acid in the pigs fed both a commercial chow and scheduled meals, indicating selective esterification of fatty acids in the erythrocyte membranes.