Dietary n-3 and n-6 Fatty Acids Alter Avian Glucose Metabolism
Source: RE Newman, WL Bryden, AC Kirby, LH Storlien, and JA Downing
This investigation studied the effects of dietary saturated and polyunsaturated fatty acids (PUFAs) from the n-3 and n-6 series on insulin action and glucose uptake in broiler chickens. 2. One-day-old male chicks were fed on a commercial starter diet for 3 weeks, randomly divided into three groups (n=6) and fed ad libitum on isonitrogenous experimental diets of equal energy density for a further 6 weeks. The diets contained 20·8g/100g protein and 80g/kg of either edible tallow, fish oil or sunflower oil, giving diets high in saturated fatty acids, n-3 PUFAs or n-6 PUFAs, respectively. 3. Jugular catheterisation was performed under general anaesthesia during week 4 of the dietary treatments and the birds given 7 d post-surgery to recover. To estimate insulin action, a bolus glucose infusion (1g/kg) was given to each chicken and sequential blood samples taken over a one-hour period. To estimate the disappearance rate of glucose from the plasma and its incorporation into tissues, 2-deoxy-D- 3 H glucose (2DG- 3 H glucose) was infused into each chicken (50µCi) 2 d later. 4. Although there were no significant differences in glucose clearance rate following the glucose infusion, the maximal insulin release in response to the glucose infusion was higher in the tallow group than in either the n-3 or n-6 PUFA dietary groups. There were no significant differences in the clearance rate of 2DG- 3 H glucose. Labelled glucose incorporation into the breast muscle was greater in birds given fish oil than in birds given tallow and significantly greater than in birds given sunflower oil. 5. The data suggest that the type of dietary fat can influence glucose metabolism and that this change in glucose utilisation may alter the energy metabolism of the broiler.