D.S. Kronfeld

Fasting hyperbilirubinemia and its relationship to free fatty acids and triglycerides in the horse.

Abstract Bilirubinemia was studied in eight horses fasted for 5 days and then refed for 5 days. In six healthy horses bilirubin rose from 1.3 ± 0.4 mg/dl (mean ± SD) in fed horses to reach a plateau of 5.3 ± 1.4 mg/dl between 64 and 136 hr of starvation. This was almost entirely due to an increase in the unconjugated bilirubin fraction. On refeeding, serum bilirubin fell to prestarvation concentrations within 2 days. Scleral icterus lagged behind changes in serum bilirubin. There was a strong positive correlation between serum bilirubin and free fatty acids, R 2 = 0.79. This correlation was not improved when differences in serum albumin were considered, so changes in the affinity of albumin for bilirubin are probably not responsible for fasting hyperbilirubinemia. Including serum triglycerides in the regression equation improved its predictive value, R 2 = 0.91. Free fatty acids may influence bilirubin metabolism as a result of competition between free fatty acids and bilirubin for binding to ligandin.

Retinol homeostasis in lambs given low and high intakes of vitamin A

Four groups of lambs were fed on a low-carotene basal diet. One group received no supplemental vitamin A (mildly deficient). Remaining groups were supplemented daily with vitamin A acetate equivalent to 100 (control) 9000 (mildly intoxicated) and 18000 (severely intoxicated) microgram retinol/kg body-weight. After 16 weeks lambs received a bolus of [15-3H]retinol intravenously; blood, urine and faeces were sampled for 48 h. Plasma retinol was complexed to a protein of 20000 molecular weight (MW), which in turn was complexed to a protein of 65000 MW; these proteins correspond respectively to retinol-binding protein and prealbumin. Plasma retinol concentration reached plateau values in intoxicated lambs, but plasma retinyl ester concentrations increased rapidly when liver contents of both retinol and retinyl esters exceeded approximately 10 and 100 mg respectively and kidney contents of both retinol and retinyl esters exceeded 30 micrograms. Labelled compounds, more polar than retinol, were found in plasma; their concentration increased tenfold in intoxicated lambs within 48 h. Plasma retinol transport rates were 0.1, 10.5 and 11.8 times control values, and clearance rates were 0.3, 14.1 and 14.3 times control values in mildly-deficient, and mildly- or severely-intoxicated lambs respectively. Turnover of retinol increased rapidly when liver contents of retinol and retinyl esters exceeded approximately 10 and 100 mg respectively and kidney contents of both retinol and retinyl esters exceeded approximately 30 micrograms. Plasma clearance of retinyl esters was unchanged with intake. Faecal excretion of tracer increased linearly with plasma retinol clearance. Our findings identify several variables that appear to be involved in retinol homeostasis, including plasma retinol clearance and excretion.

Owners' perception of food flavor preferences of pet dogs in relation to measured preferences of laboratory dogs

Abstract In this study, food flavor preferences were examined in pet dogs and in laboratory dogs by feeding the same foods to each group; 3 specially formulated dry foods differing only in flavor. Three panels of laboratory dogs were given choices between 2 of the test foods, and their preferences were determined from quantities eaten. Sixty pet dogs were given the test foods by their owners in the manner dry food was usually served. The owners rated their perception of the dogs response to each test food by using a standard rating scale. The laboratory dogs preferred some test foods over others. The pet-dog owners interpreted their dogs responses as indicating no preference for any test food over any other, although individual owners interpretations did vary. Some variables were examined in the pet dogs as a function of the variation in their perceived responses to the test foods. Variables were selected from diverse aspects of pet dogs; physical characteristics, feeding regime, behavior toward food, physical and social environments. Of the variables examined, only the dogs sex was associated with preferences for 2 of the test foods. None of the variables were associated with preferences for all 3 foods. Several were associated with preferences for only one food. The results of this study indicated a need to examine typical feeding behavior in pet dogs within the context of the home, and suggested several variables that appear to influence food flavor preferences.