Utilization of hydrolysed potato starch by juvenile Atlantic salmon Salmo salar L., when using a restricted feeding regime

A 56-day growth trial was conducted to study the utilization of hydrolysed potato starch by juvenile Atlantic salmon Salmo salar L. using a restricted feeding regime. Two diets supplemented with either 15% or 30% hydrolysed p otato starch and a control diet without carbohydrate supplementation were e ach fed to triplicate groups of salmon. Feeding rate varied from 1.4% to 2. 0% of body weight per day, so that fish were fed similar amounts of protein and lipid. In spite of the restricted feeding used. no growth stimulation was measured as a consequence of the additional starch intake. No variation was found in protein utilization, measured as protein efficiency ratio val ues (PER), while feed utilization showed decreased values as starch intake increased. Plasma glucose concentrations did not vary as a consequence of i ncreased starch intake when measured 24h after feeding, indicating efficien t regulation of plasma glucose. In fish fed the 30% starch, the plasma tria cylglycerol concentration was significantly increased, which map point to d e novo lipid synthesis from the high starch intake, No variation was found in plasma cholesterol or protein concentrations, or asparagine aminotransfe rase, alanine aminotransferase and lactate dehydrogenase activities. This s hows that the fish health status and liver function were normal (no mortali ty was registered). Liver and muscle showed increased glycogen levels as a function of increased starch intake. The same diets were also fed to juveni le white sturgeon Acipencer transmontanus and hybrid tilapia Oreochromis ni loticus x O. aureus. These results are presented separately.