C. O. Little

Utilization of rumen metabolites as energy sources in rats

Abstract The utilization of the energy from acetate, propionate, and butyrate when providing 24% of the dietary gross energy was studied in female rats weighing approximately 50 and 140 g. Substitution of acetate, propionate, or butyrate for starch and glucose did not significantly affect the digestible, metabolizable, or net energy measurements. Dietary propionate appeared to interface with normal metabolic function to the extent that this diet could not be fed to the younger rats. While older rats did have rough hair coats, reddening of the paws, and were extremely excitable, their performance was not different from that of rats receiving the control ration when measured by the parameters used in this experiment.

Influence of nitrate and nitrite on carotene disappearance from the rat intestine

Abstract Disappearance of 300 mcg doses of beta carotene in aqueous suspension with Tween “80” from the ligated small intestine of rats was studied in 4 experiments. Pretreatment with 0.4% or more KNO 3 or with 0.5% or 1% KNO 2 increased disappearance. Part of the increased carotene disappearance was accounted for by the passage of intact carotene into the blood. Vitamin A concentrations in the blood were not affected.

Influence of thyroid activity on carotene disappearance from the rat intestine

Abstract Disappearance of aqueous suspensions of beta carotene, during 3-hour incubations in the ligated intestine, was studied in three trials involving 120 rats. When 800 p.p.m. of iodinated casein was added to the diet, disappearance was significantly increased. Blood data indicate that this can be attributed to more rapid conversion of carotene to vitamin A. Adding 400 p.p.m. of iodinated casein or either 55 or 110 p.p.m. of methimazole to the diet did not affect carotene disappearance.