Effect of Different Dietary Starch Inclusion Levels on Growth Performance, Glucose Metabolism, Histological Alterations and Modulation of Hepatic Gene Expressions in Genetically Improved Labeo rohita (Jayanti Rohu)

Abstract

Background: Feed cost mainly constitutes 40-60% of total aquaculture production expenses, due to the inclusion of expensive animal-derived ingredients to the feed industry. Studies suggested that herbivore and omnivore fish species can consume higher level of carbohydrate (150–300 g/kg starch) as compared to carnivore fish. However, lower carbohydrate utilization in fishes is less understood till date. In the present work, It was attempted to decipher the physiological changes in genetically improved rohu (Jayanti Rohu) upon inclusion of different levels of starch in the feed regime. Methods: Three isonitrogenous (24% crude protein), isolipidic (10% ether extract) experimental diets viz. TS20 (@20% starch), TS30 (@30% starch) and TS40 (@40% starch) were formulated and fed to Jayanti Rohu fingerlings (180 number with average weight of 45±3.5 g) twice daily up to satiation level for 45 days experimental period. The growth performance, nutrient utilization, histological changes and modulation of hepatic gene expressions were evaluated after completion of experiment. Result: Results indicated significantly (p less than 0.05) increased weight gain percentage, SGR and condition factor in TS30 and TS40 as compared to TS20. The histoarchitecture of hepatic cells depicted greater cell damage with increasing levels of dietary carbohydrates. The glucose membrane transporter 2 gene and carbohydrate metabolism involved genes showed a higher expression in TS40 and TS30 compared to TS20. Therefore, the present study concluded that inclusion level of 30% starch as optimal level in the diet of genetically improved Jayanti rohu.