Effect of diets with similar nutrient core with increasing starch as filler in growth performance and survival of striped bass (Morone saxatilis) cultured at three different temperatures

Abstract

The present study aimed to investigate the effects of different diets with similar nutrient core (protein/lipid/micronutrient ratio) but different starch amounts (nutrient core/filler; NC/F) on the productive performance of striped bass (Morone saxatilis) juveniles exposed to different temperatures. Within this purpose, four extruded experimental diets were formulated, decreasing the amount of starch as filler with the same nutrient core with the following protein/lipid/micronutrients (vitamins+choline chloride) (P/L/Mn) ratios: 45.3/11/2.8, 47.3/12.4/3.5, 51.7/13.3/3.7, and 53.3/13.5/4.0 %. Despite the proportions of the nutrient core being the same among diets, the dietary treatments were called according to protein content in the extruded pellet: D45, D47.3, D51.7, and D53.3, respectively. Juveniles of striped bass with an average weight of 7.7 ± 0.24 g were distributed (15 fish per tank) in three recirculating systems (12 tanks each with 500 L water volume). Each system was kept at different temperatures (18, 22, and 26 °C). After eight weeks of the feeding trial, there are clear tendencies after a polynomial regression analysis for growth, feed intake, and hepatosomatic index. However, after a two-way ANOVA analysis considering all temperatures, only feed intake presented an interaction with lower values accordingly at the higher nutrient core. There is no clear tendency at suboptimal temperature, where fish probably survived at basal metabolism. The latter suggests that M. saxatilis mainly depends on the protein/lipid/micronutrient ratio at optimal temperatures to enhance performance.