An 8-week feeding experiment was conducted to determine the effect of dietary betaine levels on the growth performance, antioxidant capacity, and lipid metabolism in high-fat diet-fed blunt snout bream (Megalobrama amblycephala) with initial body weight 4.3 ± 0.1 g [mean ± SEM]. Five practical diets were formulated to contain normal-fat diet (NFD), high-fat diet (HFD), and high-fat diet with betaine addition (HFB) at difference levels (0.6, 1.2, 1.8%), respectively. The results showed that the highest final body weight (FBW), weight gain ratio (WGR), specific growth rate (SGR), condition factor (CF), and feed intake (FI) (P < 0.05) were obtained in fish fed 1.2% betaine supplementation, whereas feed conversion ratio (FCR) was significantly lower in the same group compared to others. Hepatosomatic index (HSI) and abdominal fat rate (AFR) were significantly high in fat group compared to the lowest in NDF and 1.2% betaine supplementation, while VSI and survival rate (SR) were not affected by dietary betaine supplementation. Significantly higher (P < 0.05), plasma total cholesterol (TC), triglycerides (TG), low-density lipoprotein (LDL), aspartate transaminase (AST), alanine transaminase (ALT), cortisol, and lower high-density lipoprotein (HDL) content were observed in HFD but were improved when supplemented with 1.2% betaine. In addition, increase in superoxide dismutase (SOD), catalase (CAT), and reduced glutathione (GSH) in 1.2% betaine inclusion could reverse the increasing malondialdehyde (MDA) level induced by HFD. Based on the second-order polynomial analysis, the optimum growth of blunt snout bream was observed in fish fed HFD supplemented with 1.2% betaine. HFD upregulated fatty acid synthase messenger RNA (mRNA) expression and downregulated carnitine palmitoyltransferase 1, peroxisome proliferator-activated receptor α, and microsomal triglyceride transfer protein mRNA expression; nevertheless, 1.2% betaine supplementation significantly reversed these HFD-induced effects, implying suppression of fatty acid synthesis, β-oxidation, and lipid transport. This present study indicated that inclusion of betaine (1.2%) can significantly improve growth performance and antioxidant defenses, as well as reduce fatty acid synthesis and enhance mitochondrial β-oxidation and lipid transportation in high-fat diet-fed blunt snout bream, thus effectively alleviating fat accumulation in the liver by changing lipid metabolism.

This study investigated the effects of xylooligosaccharide (XOS) supplementation on growth, intestinal enzyme, antioxidant and immune‐related genes in common carp Cyprinus carpio fed a high‐fat diet (HFD). One hundred and ninety two fish with an initial weight of 19.61 ± 0.96 g were allocated into 24 tanks (eight fish per tank in four replicate) and were fed the control diet, HFD, HFD with 0.5%, 1%, 2% and 3% XOS supplementation. From the result, fish offered HFD with 1% XOS supplementation significantly obtained a higher body mass index and feed efficiency ratio, whereas condition factor was higher in fish fed HFD supplemented with 2% XOS but no difference was attributed to other supplemented group compared to control group. Also, fish fed HFD supplemented with 1%–2% XOS significantly improved protease, lipase, creatine kinase and sodium/potassium ATPase activities compared to other groups. Fish offered HFD were significantly lower in superoxide dismutase (SOD), catalase, glutathione peroxidase (GPX), myeloperoxidase, acid phosphatase, lysozyme activities and immunoglobulin content, but the opposite result was found for aspartate transaminase, alanine transaminase activities, malondialdehyde, protein carbonyl and cortisol content as compared with the control. However, this effect was reversed with HFD supplemented with XOS. Also, interleukin 1β, interleukin 8, tumour necrosis factors, interferons, caspase‐3 and caspase‐9 in the intestine were all up‐regulated in the HFD group, while the reverse pattern was found in SOD, GPX, lysozyme‐C, complement 3 and mucin 5b (muc5b), than the control group. These effects were all enhanced by feeding the XOS diet, especially those fed 1%–3% supplementation. In conclusion, XOS inclusion can improve the growth, digestive enzymes, antioxidants and immune response of common carp fed HFD.

This study established the effects of betaine and choline association on lipid metabolism of blunt snout bream (Megalobrama amblycephala) fed high-fat diet (HFD).Fish (43.73 ± 0.13 g) were randomly distributed into 21 cages in seven groups (three replicates) and fed with control diet, HFD and HFD+ betaine and choline associated at different levels (16, 12, 8, 4 or 0 g/kg betaine and 0, 2, 4, 6 or 8 g/kg choline), designated as diet 1, diet 2, diet 3, diet 4, diet 5, diet 6 and diet 7 respectively for 8 weeks. Fish fed diet 4 obtained higher final body weight, weight gain and specific growth rate whereas feed conversion ratio showed the opposite trend compared to those fed HFD. Higher plasma levels of cholesterol, triglycerides, low-density lipoprotein tHcy and low levels of high-density lipoprotein, S-adenosylmethionine, S-adenosylhomocysteine were observed in fish fed HFD; the opposite was true for fish fed diet 4. Also, a lower liver superoxide dismutase, glutathione peroxidase activities and a higher malondialdehyde content were observed in fish fed HFD. This effect was reversed with fish fed diet 4. The transcription of Betaine-homocysteine S-methyl-transferase1, glycine N-methyltransferase and monoacylglycerol O-acyltransferase 1 were upregulated in fish fed HFD. The opposite trend was observed in fish fed diet 4. In conclusion, betaine and choline associated diets can benefit growth and lipid metabolism of blunt snout bream fed HFD. K E Y W O R D S antioxidant capacity, betaine, choline, growth performance, lipid metabolism, Megalobrama amblycephala

No abstract

This study was conducted to understand the effects of glycyrrhetinic acid, berberine, and resveratrol on growth and inflammatory signalling in channel catfish fed a high-fat diet (HFD). Fish (average weight, 20 ± 0.15 g) were distributed randomly in 15 tanks (11 fish per tank). Fish were allocated randomly to five experimental diets: (control diet (ND); high-fat diet (HFD); high-fat diet + 0.3 mg/kg glycyrrhetinic acid (HFD + GA); high-fat diet + 50 mg/kg berberine (HFD + B); and high-fat diet + 400 mg/kg resveratrol (HFD + R). Each diet was tested in triplicates for eight weeks. The final body weight (FBW), body weight gain (BWG), specific growth rate (SGR), and condition factor (CF) were significantly lower in fish fed HFD. In contrast, opposite trends were observed in the feed conversion ratio (FCR), hepatosomatic index (HSI), visceralsomatic index (VSI), and mesenteric fat index (MFI). Fish fed HFD showed a higher trend ( P < 0.05 ) in plasma glucose, cortisol, aspartate aminotransferase (AST), alanine aminotransferase (ALT), liver total cholesterol (TC), triglycerides (TG), and low-density lipoprotein (LDL), while opposite trends were found in total protein (TP) and high-density lipoprotein (HDL). These parameters were all enhanced by feeding the additive-supplemented diets. Liver superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), plasma lysozyme (LYM), myeloperoxidase (MPO), alkaline phosphatase (AKP), acid phosphatase (ACP) activities, and immunoglobulin M (IgM) levels were all lower in fish fed HFD as compared to the control group. However, supplementing GA, berberine, and resveratrol restored these parameters to similar levels to the control group. Upregulated gene expression of interleukin 1β (IL-1ß), nitric oxide (NOS), nuclear factor-kappa B (NF-κB), X box-binding protein 1 (XBP1s), coupled with tumour necrosis factor-alpha (TNF-α), and interferon-gamma (IFN-γ), was observed in fish fed HFD, whereas reverse trends were observed in the additive-supplemented groups as compared to the control group. Overall, glycyrrhetinic acid, berberine, and resveratrol could reduce endoplasmic reticulum stress and inflammation and enhance the immune response in channel catfish fed HFD.