Effect of dietary oxidized fish oil on growth performance, physiological homeostasis and intestinal microbiome in hybrid grouper (♀ Epi-nephelus fuscoguttatus × ♂ Epinephelus lanceolatus)

Effects of Apple Polyphenols and Taurine on Growth Performance, Tissue Morphology, and Lipid and Glucose Metabolism in Rice Field Eel (Monopterus albus) Fed High Oxidized Fish Oil

“…This is similar to those observed in largemouth bass (Micropterus salmoides) [40]. However, contrasting results have been reported that the addition of OFO to diets led to a reduced SGR in blunt snout bream (Megalobrama amblycephala) [41], rohu (Labeo rohita) [5], and hybrid grouper (♀ Epinephelus fuscoguttatus × ♂ Epinephelus lanceolatus) [42]. These discrepancies might be attributed to nature of the rice field eel as a burrowing animal with a sensitive sense of smell, making it more inclined to feed when exposed to the distinctive scent of OFO [43].…”

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

“…Body index is also an important parameter reflecting fish growth, and the viscera and muscle tissue are important contributors to body lipid deposition. The increased body indexes (VSI, HSI and CF) were mainly related to the high dietary lipid content [19]. In this study, the body indexes (VSI, HSI, CF) and body lipid content depressed linearly with the increasing dietary MDA level, although all experimental diets were iso-lipidic.…”

“…Similarly, the growth rate (WGR, SGR), feed utilization (FCR, PER), and body lipid content of the hybrid grouper were depressed by dietary supplementation with 8.86 and 17.72 mg/kg MDA in this study. Additionally, previous studies showed that oxidized oil inhabited the growth rate of orange spotted grouper Epinephelu coioides [23,24], Japanese sea bass Lateolabrax japonicus [25], Rhynchocypris lagowski Dybowski [26], Wuchang bream Megalobrama amblycephala [27], tilapia Oreochromis niloticus [28] and pearl gentian grouper Epinephelus fuscoguttatus♀× E. lanceolatus♂ [19]. It deemed that the adverse effect of oxidized oil on the lipid digestion and absorption of grass carp [6] may mainly be attributed to dietary MDA present in oxidized oil.…”

“…Digestive enzymes hydrolyze large molecules of nutrients into small molecules for absorption and utilization by fish [29]. Hence, digestive enzyme activities can reflect the digestive capacity of fish [19]. In this study, dietary MDA inclusion level exceeding 8.86 mg/kg reduced the intestinal digestion (stomach, trypsin, lipase, amylase and maltase) and absorption (Na + /K + -ATPase, Ca 2+ /Mg 2+ -ATPase) enzyme activities, suggesting that high doses of dietary MDA impaired the digestion and absorption capacity of hybrid grouper.…”

“…The feeds were placed in the shade to dry naturally for two days and then stored at −20 • C. Six experimental diets (M0, M1, M2, M4, M8, and M16) were formulated by splashing different concentrations of MDA solution before each feeding as an addition to different dietary MDA levels. The MDA standard solution (100 µg/mL) was prepared according to GB/T 5009.181-2016: dissolve 0.315 g 1,1,3,3-tetrathoxypropane (purity ≥ 97%; Macklin Biochemical Co., Ltd., Shanghai, China) in distilled water and dilute to 1000 mL, store at 4 • C. Experimental diets were sprayed with 10 mL of MDA solution with different MDA levels (0, 0.22, 0.44, 0.88, 1.76 and 3.52 mL of MDA standard solution was diluted to 10 mL with distilled water, respectively), which referenced the MDA concentration of commercial feeds for grouper and experimental diets for grass carp [6] and hybrid grouper [19]. To determine the MDA content in diets, crude lipid in the diets was firstly extracted and then, using commercial kits (Nanjing Jiancheng Bioengineering Institute, Nanjing, China) for measuring MDA content according to the instruction, the actual MDA content was measured to be 0.03, 1.11, 2.21, 4.43, 8.86 and 17.72 mg/kg of diets M0, M1, M2, M4, M8, and M16, respectively.…”