Dietary Malondialdehyde Damage to the Growth Performance and Digestive Function of Hybrid Grouper (Epinephelus fuscoguttatus♀ × E. lanceolatu♂)

SIMPLE SUMMARY: Few studies have been conducted on the harmful effects of MDA levels in aquafeeds on animals. This study aimed to investigate the effect of dietary MDA on the growth performance and digestive function of hybrid groupers (Epinephelus fuscoguttatus♀ × E. lanceolatu♂). Six isoproteic and isolipidic diets were formulated to contain 0.03, 1.11, 2.21, 4.43, 8.86 and 17.72 mg/kg of MDA, respectively. Each diet was randomly assigned to triplicates of 30 juveniles (14.47 ± 0.01 g) per tank in a flowing water culture system. It shows that the effect of MDA on hybrid groupers showed a dose-dependent effect on this study. A low dose of dietary MDA had limited effects on the growth performance and intestinal health of hybrid group-ers, while a high concentration damaged the gastrointestinal structure and negatively impacted the intestinal digestive and antioxidant functions, and thereby impaired the growth and health of hybrid groupers. ABSTRACT: Malondialdehyde (MDA) is the dominant component of lipid peroxidation products. Improper storage and transportation can elevate the lipid deterioration MDA content of diets to values that are unsafe for aquatic animals and even hazardous to human health. The study aimed to investigate the effect of dietary MDA on growth performance and digestive function of hybrid grouper (Epinephelus fuscoguttatus♀ × E. lanceolatu♂). Six isoproteic and isolipidic diets were formulated to contain 0.03, 1.11, 2.21, 4.43, 8.86 and 17.72 mg/kg MDA, respectively. The study shows that the increased dietary MDA content linearly reduced the growth rate, feed utilization, body index and body lipid content of hybrid grouper, while the low dose of dietary MDA (≤2.21 mg/kg) created no difference. Similarly, dietary MDA inclusion linearly depressed the activities of intestinal digestive and absorptive enzymes as well as antioxidant enzymes, enhanced the serum diamine oxidase activity, endotoxin level and intestinal MDA content. A high dose of MDA (≥4.43 mg/kg) generally impaired the gastric and intestinal mucosa, up-regulated the relative expression of Kelch-like ECH-associated protein 1 but down-regulated the relative expression of nuclear factor erythroid 2-related factor 2 in hindgut. In conclusion, the effect of MDA on hybrid grouper showed a dose-dependent effect in this study. A low dose of dietary MDA had limited effects on growth performance and intestinal health of hybrid grouper, while a high concentration damaged the gastrointestinal structure, depressed the intestinal digestive and antioxidant functions, and thereby impaired the growth and health of hybrid grouper.