Mechanistic evaluation of fermented sugar beet pulp on growth, metabolic responses, antioxidant status, immunity, and physiological health in Labeo rohita

Abstract

This study evaluated the use of fermented sugar beet pulp (FSBP) as a feed ingredient for juvenile Labeo rohita (initial weight, 15 g). A completely randomized design (CRD) with seven dietary treatments and three replicates per treatment was used for a 12-week feeding trial. The diets included a control (0% sugar beet pulp, SBP), three treatments with raw SBP (RSBP) at 7%, 14%, and 21%, and three treatments with FSBP at the same inclusion levels. Fermentation was carried out using liquid baker’s yeast waste as the fermenting agent. After the feeding trial, growth performance and whole-body composition were assessed. Whole-blood, serum, liver, and intestinal samples were analyzed for hematological indices, biochemical parameters, antioxidant enzyme activities, and digestive enzyme activities, respectively. Fish fed the 21% FSBP diet (T6) showed the highest final body weight, net weight gain, specific growth rate, feed efficiency, and protein efficiency ratio, together with the lowest feed conversion ratio, compared with fish fed the control and RSBP-based diets (p < 0.05). Whole-body crude protein content was significantly higher in fish fed the 21% FSBP diet than in all other dietary groups (p < 0.05). Hepatic CAT, GPx, and SOD activities and intestinal protease, amylase, and lipase activities were highest in fish fed T6 and lowest in fish fed the 21% RSBP diet (T3) (p < 0.05). Whole-blood Hb, RBC count, HCT, WBC count, and platelet count were significantly higher in fish fed T6 than in fish fed T3, whereas serum ALT, AST, ALP, and LDH activities and triglyceride concentration were significantly lower, and total protein concentration was significantly higher in T6 than in T3 (p < 0.05). Collectively, these findings indicate that fermentation enhanced the nutritional profile and health-related benefits of SBP, with FSBP supplementation up to 21% improving growth, antioxidant response, and liver health without adverse effects on the parameters assessed. FSBP presents a cost-effective raw material for use in aquafeeds, supporting enhanced L. rohita production.

Graphical Abstract