Effects of the fishmeal freshness on growth performance, immune response, hepatopancreatic health and anti-stress capacity of giant freshwater prawn (Macrobrachium rosenbergii)

Fishmeal is one of the main protein sources in aquafeed, and its quality directly affects the growth and health of aquatic animals. This research assessed the influence of fishmeal freshness on the growth, immune function, hepatopancreatic health and stress resistance of giant freshwater prawn. Prawns (2.36 ± 0.01 g) were assigned to three experimental diets containing domestic fishmeal with different total volatile basic nitrogen (TVB-N), including DT55 (Dietary TVB-N = 55 mg/100 g), DT65 (Dietary TVB-N = 65 mg/100 g), and DT76 (Dietary TVB-N = 80 mg/100 g). After the experimental period, the DT65 and DT80 diets significantly impaired growth performance and increased the feed conversion ratio (FCR) ( P < 0.05). Additionally, activities of hemolymph alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were markedly increased in the DT65 and DT80 groups, while total protein (TP) and nitric oxide (NO) contents showed the opposite trend ( P < 0.05). Moreover, the hepatopancreatic antioxidant system was significantly suppressed in the DT65 and DT80 groups, as indicated by marked reductions in total antioxidant capacity (T-AOC) and activities of antioxidant enzymes ( P < 0.05). In line with these changes, the hepatopancreatic expression of the apoptosis-related genes caspase 8 , caspase 9 , and bok were significantly up-regulated in the DT65 and DT80 groups, while the mRNA levels of the anti-apoptotic iap was significantly decreased ( P < 0.05). Finally, high-temperature and ammonia nitrogen stress tests demonstrated a significant decline in the survival rate of prawns in the DT65 and DT80 groups. Overall, these findings underscore the critical importance of the ingredient freshness in formulated diets for prawn, recommending that dietary TVB-N level not exceed 65 mg/100 g. • Fishmeal freshness affected the growth and feed utilization of prawns. • Dietary TVB-N above 65 mg/100 g compromised the immune response of prawns. • Dietary TVB-N above 65 mg/100 g induced the hepatopancreatic apoptosis of prawns. • Dietary TVB-N above 65 mg/100 g reduced prawn tolerance to ammonia-N and high-temperature stress. • The freshness of fishmeal is crucial for the growth and health of prawns.