Effects of age and diet on plasma lipid and glucose concentrations in genetically lean or fat chickens

Three experiments were carried out to compare plasma lipid and glucose concentrations in genetically lean (LL) and fat (FL) male chickens. The fat birds always displayed lower glycemia than the lean ones, irrespective of the diet (low-fat or fatty) and nutritional state (fed or fasted). Conversely, triglyceridemia was higher in the fat than in the lean line, particularly in the fed condition. This difference was more pronounced in the birds fed on a low-fat diet and became still more marked as they aged. No consistent differences were found between the two lines as to cholesterolemia and non-esterified fatty acid concentrations. Injections of Triton WR 1339 increased triglyceridemia; this effect tended to be more pronounced in the fat birds. The rate of increase of triglyceridemia did not plateau as the dose of Triton increased. The injection of Triton frequently led to convulsions and death. It is concluded that this model of genetic fatness is different from the monogenic models of mammalian obesity since hypertriglyceridemia was not systematic and was not associated with hyperglycemia or hyperinsulinemia.