Search

A feeding study lasting 30 days was carried out to determine the effects of dietary Oryzanol (Ory) on the survival, growth, antioxidant capacity, peptic enzymes, as well as lipid metabolism of Larimichthys crocea larvae (11.87 ± 0.59 mg) using four different Ory concentrations in microfeed formulations (0, 20, 40, and 80 mg/kg), all preserving isolipidic (18.25% crude lipid) and isonitrogenous (52.08% crude protein) conditions. Results revealed that larvae given 40 and 80 mg/kg Ory revealed markedly higher survival rates; in particular, the 80 mg/kg Ory larvae exhibited a considerably higher specific growth rate than the control. Furthermore, the 80 mg/kg dietary Ory resulted in increased peptic enzyme activity, indicating heightened digestive capabilities of larvae. Meanwhile, Ory supplementation at 20, 40, and 80 mg/kg also increased antioxidant enzyme activities and reduced malondialdehyde levels, indicating an enhanced antioxidant capacity. Moreover, the incorporation of 20 and 40 mg/kg Ory demonstrated efficacy in enhancing the lipid metabolism of the larvae. This was evident in the reduction of triglyceride and total cholesterol levels in the larval visceral mass, attributed to the downregulation of genes that participate in lipid synthesis, and the upregulation of genes associated with lipid catabolism. Overall, the study suggests that the addition of Ory (ranging from 40 to 80 mg/kg) significantly improves both survival and developmental aspects, possibly mediated by enhanced digestion and antioxidative effects, alongside the induction of lipid metabolism in Larimichthys crocea larvae. [ABSTRACT FROM AUTHOR]

A 30-day feeding trial was conducted to determine the effects of dietary glycyrrhizin (GL) on survival, growth performance, expression of feeding-related genes, activities of digestive enzymes, antioxidant capacity, and expression of inflammatory factors of large yellow croaker larvae with an initial weight of 3.78 ± 0.27 mg. Four 53.80% crude protein and 16.40% crude lipid diets were formulated with supplementation of 0%, 0.005%, 0.01%, and 0.02% GL, respectively. Results indicated that larvae fed diets with GL had higher survival rate and specific growth rate than the control (P < 0.05). Compared with the control, the mRNA expression of orexigenic factor genes including neuropeptide Y (npy) and agouti-related protein (agrp) were significantly increased in larvae fed the diet with 0.005% GL, while the mRNA expression of anorexigenic factor genes including thyrotropin-releasing hormone (trh), cocaine and amphetamine regulated transcript (cart), and leptin receptor (lepr) were significantly decreased in larvae fed the diet with 0.005% GL (P < 0.05). The trypsin activity in larvae fed the diet with 0.005% GL was significantly higher than the control (P < 0.05). The alkaline phosphatase (AKP) activity in larvae fed the diet with 0.01% GL was significantly higher than the control (P < 0.05). A clear increase of total glutathione (T-GSH) content, activities of superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px) was observed in larvae fed the diet with 0.01% GL compared with the control (P < 0.05). Moreover, the mRNA expression of interleukin-1β (il-1β) and interleukin-6 (il-6) (proinflammatory genes) in larvae fed the diet with 0.02% GL were significantly lower than the control (P < 0.05). In conclusion, the supplementation of 0.005% -0.01% GL could enhance the expression of orexigenic factor genes, activities of digestive enzymes and antioxidant capacity, ultimately improving the survival, and growth performance of large yellow croaker larvae. [ABSTRACT FROM AUTHOR]

A 30-day feeding trial was designed to investigate the physical properties of chitosan-coated microdiet (CCD) and the effect of CCD on survival, growth performance, activities of digestive enzymes, intestinal development, antioxidant capacity, and inflammatory response of large yellow croaker larvae (initial weight: 3.81 ± 0.20 mg). Four isonitrogenous (50% crude protein) and isolipidic (20% crude lipid) microdiets were prepared with different concentrations of chitosan wall material by spray drying method (0.00%, 0.30%, 0.60%, and 0.90%, weight (chitosan) : volume (acetic acid)). Results showed that the lipid encapsulation efficiency (control: 60.52%, Diet1: 84.63%, Diet2: 88.06%, Diet3: 88.65%) and nitrogen retention efficiency (control: 63.76%, Diet1: 76.14%, Diet2: 79.52%, Diet3: 84.68%) correlated positively with the concentration of wall material (P < 0.05). Furthermore, the loss rate of CCD was significantly lower than the uncoated diet. Larvae fed the diet with 0.60% CCD had significantly higher specific growth rate (13.52 and 9.95%/day) and survival rate (14.73 and 12.58%) compared to the control group (P < 0.05). Larvae fed the diet with 0.30% CCD had significantly higher trypsin activity in pancreatic segments than the control group (4.47 and 3.05 U/mg protein) (P < 0.05). Larvae fed the diet with 0.60% CCD had significantly higher activity of leucine aminopeptidase (7.29 and 4.77 mU/mg protein) and alkaline phosphatase (83.37 and 46.09 U/mg protein) in the brush border membrane than those of the control group (P < 0.05). The intestinal epithelial proliferation- and differentiation-related factors (zo-1, zo-2, and pcna) in larvae fed the diet with 0.30% CCD had higher expression than those of the control group (P < 0.05). When the concentration of wall material reached 0.90%, the larvae had significantly higher superoxide dismutase activity than that of the control group (27.27 and 13.72 U/mg protein) (P < 0.05). Meanwhile, malondialdehyde contents were significantly lower in larvae fed the diet with 0.90% CCD than that of the control group (8.79 and 6.79 nmol/mg protein) (P < 0.05). 0.30%~0.60% CCD significantly increased the activity of total nitric oxide synthase (2.31, 2.60, and 2.05 mU/mg protein) and inducible nitric oxide synthase (1.91, 2.01, and 1.63 mU/mg protein) and had significantly higher transcriptional levels of inflammatory factor genes (il-1β, tnf-α, and il-6) than those of the control group (P < 0.05). The results indicated chitosan-coated microdiet had great potential in feeding large yellow croaker larvae in addition to reducing nutrition loss. [ABSTRACT FROM AUTHOR]

A 30‐day feeding experiment was operated to evaluate the impact of astaxanthin (Ast) on growth performance, activities of digestive enzymes, antioxidant responses and lipid metabolism of large yellow croaker (Larimichthys crocea) larvae. Four micro‐diets (isonitrogenous and isolipidic) were formulated with graded Ast levels (0, 20, 40 and 80 mg/kg) in form of Haematococcus pluvialis powder (0, 0.4, 0.8 and 1.6 g/kg). Results showed that the specific growth rate of larvae was significantly enhanced by supplementation of 80 mg/kg Ast compared to the control group. Meanwhile, the Ast supplementation could significantly improve the digestive capacity of larvae through increasing activities of digestive enzymes, including trypsin in larvae pancreas segments (PS) and intestinal segments (IS), lipase, and alkaline phosphatase in brush border membranes compared to the control group. In terms of antioxidants, Ast supplementation significantly advanced the antioxidant capacity through increasing the activity of total antioxidant capacity and catalase, and reducing content of malondialdehyde. The activity of lysozyme and nitric oxide content of larvae were significantly increased by Ast supplementation compared to the control group. Furthermore, the triglyceride content in visceral mass was significantly reduced by Ast supplementation probably through up‐regulating expression of lipid catabolism‐related genes (cpt1, lpl, hl, aco, and ppar‐α), and down‐regulating expression of lipogenesis‐related genes (fas, dgat2, and srebp1) and lipid transport‐related genes (fabp11, apoB100, and mtp). In summary, appropriate supplementation of Ast (40–80 mg/kg) could improve the growth performance of large yellow croaker larvae through enhancing of digestive enzymes activities, antioxidant capacity and promoting lipid utilization. [ABSTRACT FROM AUTHOR]

A 10-week feeding trial was conducted to evaluate the effect of dietary methionine (MET) on the growth performance, lipid metabolism and liver antioxidant function in juvenile large yellow croaker (Larimichthys crocea) fed with high lipid diets (HLDs). Large yellow croaker with an initial average weight of 8.59 g, were fed with basic HLD (lipid level at 18%, HL), basic HLD supplemented with 0.6% MET (HL/L-MET) and basic HLD supplemented with 1.2% MET (HL/H-MET). Results indicated that dietary MET did not affect weight gain, specific growth rate and feed efficiency ratio (P > 0.05). The MET supplementation in large yellow croaker also did not affect the content of total lipid in whole body (HL = 9.57, HL/L-MET = 8.92 and HL/H-MET = 8.71%), liver (7.34 , 16.68 and 14.37%) and muscle (10.87 , 12.11 and 9.94%) (P > 0.05). However, MET supplementation reduced the size and number of liver lipid droplets as dietary MET increased. Meanwhile, supplementation of MET in HLDs reduced serum total cholesterol (2.65, 2.14 and 1.91 mmol/L), low-density lipoprotein-cholesterol (0.27, 0.21 and 0.16 mmol/L) and triglyceride (4.80, 2.43 and 1.96 mmol/L) (P < 0.05), but increased serum high-density lipoprotein-cholesterol (0.68, 0.77 and 0.83 mmol/L) (P < 0.05). Dietary MET upregulated significantly the mRNA expression of genes related to mitochondrial fatty acid β-oxidation (PPARα and CPT1) and ER stress (GRP78, ATF6α and CHOP) (P < 0.05). Furthermore, feeding fish with MET diets reduced serum alanine transaminase and aspartate transaminase activities, serum and liver malondialdehyde content, and liver 8-hydroxydeoxyguanosine level. Interestingly, feeding fish with MET diets increased liver total antioxidant capacity activity (P < 0.05). In conclusion, dietary MET improved lipid metabolism and increased antioxidant capacity in the liver, but did not affect growth performance in juvenile large yellow croaker fed with HLDs. • Dietary methionine could not affect growth performance. • Dietary methionine decreased serum lipid profile, but not liver fat deposition. • Dietary methionine upregulated gene expression of mitochondrial FA β-oxidation. • Dietary methionine increased gene expression of endoplasmic reticulum stress. • Dietary methionine reduced liver damage and improved hepatic anti-oxidative defenses. [ABSTRACT FROM AUTHOR]

Marine fish at early life is vulnerable to the threat of external pathogenic bacteria with unestablished intestinal flora. Early life intervention could contribute to healthy development of larvae gut tract. Consequently, the present study examined how large yellow croaker larvae (Larimichthys crocea) (mean body weight 3.64 ± 0.20 mg) responde to fecal microbiota came from 12-month-old large yellow croaker by oral administration. The intestinal contents of the donor were prepared into bacterial solution and sprayed on the Micro-diet. After 30 days feeding, growth performance, intestinal development, digestive ability and gut microbiota of larvae were detected. Results showed that there was no significant difference in survival rate. After fecal microbiota transplantation (FMT) treatment fish larvae had significantly higher final body weight, weight gain rate and specific growth rate. FMT treatment remarkably enhanced the activities of α-amylase and trypsin in intestinal segment and the activity of lipase and trypsin in pancreatic segment. Furthermore, FMT treatment significantly increased the activity of leucine-aminopeptidase on brush border membrane and the mRNA expression of pcna and occludin compared with the control group. Similarly, gut in larvae of FMT group had significantly higher villus height and muscular thickness. Moreover, FMT treatment significantly improved the activity of lysozyme and decreased malondialdehyde concentration in visceral mass. FMT treatment increased intestinal microbial diversities and altered intestinal microbiota profile of larvae. Spearman analysis revealed that FMT profoundly influenced the function of gut microbiota. Bacteria introduced by FMT may play a role in digestion and intestinal tract development. In conclusion, our results revealed that FMT treatment improved microbial diversity and modulated intestinal microecology of large yellow coraker larvae, which could significantly affect the digestive capacity, antioxidant capacity, intestinal development and intestinal health, thus improved its growth performance. • FMT might modulate intestinal microecology of large yellow croaker larvae by introducing multiple microbiota. • FMT did no harm to large yellow croaker larvae and promoted its growth performance. • Microbiota introduced by transplantation significantly promoted intestinal health of large yellow croaker larvae. [ABSTRACT FROM AUTHOR]