Assessment of tiger nut (Cyperus esculentus) cake as feed ingredient for largemouth bass (Micropterus salmoides)

Tiger nut cake (TNC) has been shown to have antioxidant and immunomodulatory properties. Largemouth bass ( Micropterus salmoides ) with an average weight of 28.72 ± 0.01 g were fed experimental diets containing different levels of TNC (0 %, 5 %, 10 %, 15 %, 20 %, 25 %) for 58 days. Results showed that dietary TNC inclusion increased feed intake and hepatosomatic index, with the highest values observed in the TNC25 group. However, no significant differences were observed among treatment groups in weight gain, specific growth rate, or condition factor. An increase in protein efficiency ratio, hepatic alanine aminotransferase activity, and intestinal lipase activity, along with a decrease in feed conversion ratio, suggested that low-level (5 %) TNC inclusion improved feed utilization. Moreover, moderate (10–15 %) TNC supplementation generally improved hepatic glucose metabolism, as evidenced by increased plasma total bile acid level and activities of glucosekinase, hexokinase, and phosphofructokinase, along with the upregulation of hexokinase, glucose-6-phosphate dehydrogenase, glucose-6-phosphatase, and fructose-1,6-bisphosphatase. High-level (20–25 %) TNC inclusion may benefit liver health by reducing plasma aspartate aminotransferase/alanine aminotransferase ratio and improving liver tissue morphology. Increasing dietary TNC levels promoted muscle mass development. Higher dietary TNC levels increased the hardness and gumminess of dorsal muscle, whereas moderate supplementation (10–15 %) improved their springiness and chewiness. In summary, TNC can effectively replace wheat flour, rice bran, and soybean oil in largemouth bass diets, with the recommended inclusion levels estimated at 6–12 % based on the broken-line regression analysis. • Inclusion of 6–12 % tiger nut cake improved feed utilization without impairing growth. • A 12 % inclusion level improved glucose metabolism and muscle texture in largemouth bass. • Higher inclusion levels (20–25 %) promoted hepatic health in largemouth bass.