Dietary supplementation with succinic acid improves growth performance and flesh quality of adult Nile tilapia(Oreochromis niloticus)fed a high-carbohydrate diet

To evaluate the effects of dietary supplementation with succinic acid on growth performance,flesh quality,glucose,and lipid metabolism of Nile tilapia(Oreochromis niloticus)fed a high-carbohydrate diet(HCD),five iso-nitrogenous and iso-lipidic diets were prepared as follows:HCD(control group)consisting of 55%corn starch and HCD supplemented with 0.5%,1.0%,2.0%,and 4.0%succinic acid,respectively.Tilapia with an initial body weight of 204.90±1.23 g randomly assigned to 15 tanks with 3 replicates per group and 10 fish per tank fed for 8 weeks.Increasing dietary succinic acid supplementation resulted in significant second-order polynomial relationship in the weight gain rate(WGR),specific growth rate(SGR),feed conversion ratio(FCR),protein efficiency rate(PER),viscerosomatic index,condition factor,and contents of muscular crude lipid and glycogen(P<0.05).The hepatosomatic index,mesenteric fat index,liver glycogen content and crude lipid contents of the whole-body and liver demonstrated significantly linear and second-order polynomial relationship(P<0.05).Quadratic curve model analysis based on WGR,SGR,PER,and FCR demonstrated that optimal supplementation with succinic acid in the HCD of Nile tilapia ranged from 1.83%to 2.43%.Fish fed with 1.0%succinic acid had higher muscular hardness,increased the contents of alkali-soluble hydroxyproline in collagen,docosahexaenoic acid(DHA)and n-3 polyunsaturated fatty acid(n-3PUFA)in muscle,and lower total fatty acid content in muscle(P<0.05)compared with the control group.Compared to the control group,dietary supplementation with 1.0%succinic acid significantly increased the contents of total bounding amino acid(arginine,histidine,isoleucine,lysine,methionine,alanine,proline),total flavor amino acid(free aspartic acid),the catalase(CAT)activity and total antioxidant capacity,and the mRNA relative expression levels of CAT,superoxide dismutase(SOD),and nuclearfactor erythroidderived 2-like 2(Nrf2)in muscle(P<0.05).Furthermore,succinic acid supplementation significantly up-regulated mRNA relative expression levels of glycolysis genes(hexokinase 2[HK2],phosphofructokinase,muscle-A[PFKMA],and phosphofructokinase,muscle-B[PFKMB]),a key glycogen synthesis gene(glycogen synthase[GYS]),and lipid catabolism genes(carnitine palmitoyltransferase-1B[CPT1B],hormone sensitive lipase[HSL],and lipoprotein lipase[LPL]),while down-regulating the mRNA relative expression level of fatty acid synthase(FASN)in muscle(P<0.05).In conclusion,dietary supplementation with 1.83%to 2.43%succinic acid improved muscle quality by increasing muscle antioxidant capacity and hardness,changing muscle amino acid and fatty acid composition,and regulating muscle glucose and lipid metabolism.

Uridine alleviates high-carbohydrate diet-induced metabolic syndromes by activating sirt1/AMPK signaling pathway and promoting glycogen synthesis in Nile tilapia(Oreochromis niloticus)

Carbohydrates have a protein sparing effect,but long-term feeding of a high-carbohydrate diet(HCD)leads to metabolic disorders due to the limited utilization efficiency of carbohydrates in fish.How to mitigate the negative effects induced by HCD is crucial for the rapid development of aquaculture.Uridine is a pyrimidine nucleoside that plays a vital role in regulating lipid and glucose metabolism,but whether uridine can alleviate metabolic syndromes induced by HCD remains unknown.In this study,a total of480 Nile tilapia(Oreochromis niloticus)(average initial weight 5.02±0.03 g)were fed with 4 diets,including a control diet(CON),HCD,HCD+500 mg/kg uridine(HCUL)and HCD+5,000 mg/kg uridine(HCUH),for 8 weeks.The results showed that addition of uridine decreased hepatic lipid,serum glucose,triglyceride and cholesterol(P<0.05).Further analysis indicated that higher concentration of uridine activated the sirtuin1(sirt1)/adenosine 5-monophosphate-activated protein kinase(AMPK)signaling pathway to increase lipid catabolism and glycolysis while decreasing lipogenesis(P<0.05).Besides,uridine increased the activity of glycogen synthesis-related enzymes(P<0.05).This study suggested that uridine could alleviate HCD-induced metabolic syndrome by activating the sirt1/AMPK signaling pathway and promoting glycogen synthesis.This finding reveals the function of uridine in fish metabolism and facilitates the development of new additives in aquatic feeds.

Dietary manipulation and testosterone replacement therapy may explain changes in body composition after spinal cord injury: A retrospective case report

BACKGROUND Reduced level of physical activity,high-fat diet and skeletal muscle atrophy are key factors that are likely to contribute to deleterious changes in body composition and metabolic following spinal cord injury (SCI).Reduced caloric intake with lowering percentage macronutrients of fat and increasing protein intake may likely to improve body composition parameters and decrease ectopic adiposity after SCI.AIM To highlight the effects of dietary manipulation and testosterone replacement therapy (TRT) on body composition after SCI METHODS A 31-year-old male with T5 SCI was administered transdermal TRT daily for 16 wk.Caloric intake and percentage macronutrients were analyzed using dietary recalls.Magnetic resonance imaging and dual-energy x-ray absorptiometry were used to measure changes in body composition.RESULTS Caloric intake and fat percentage were reduced by 445 kcal/d and 6.5%,respectively.Total body weight decreased by 8%,body fat decreased by 29%,and lean mass increased by 7%.Thigh subcutaneous adipose tissue cross-sectional area was reduced by 31%.CONCLUSION Manipulation of caloric intake,fat percentage,and protein percentage may have influenced body composition after SCI.

Liver fibrosis in primary intestinal lymphangiectasia: An undervalued topic

The relationship between primary intestinal lymphangiectasia(PIL) and liver fibrosis is an emerging topic with many obscure aspects due to the rarity of the disorder.A recent paper reported that a six-month lowfat diet improved liver fibrosis.We report the case of a 17-year-old girl affected by PIL whose hepatic fibrosis progressively worsened within one year,despite dietetic support.This and the previous case report describe extraordinary events,which do not allow clear-cut clinical aspects to be established.Nevertheless,both cases suggest that in patients with PIL,it is necessary to closely monitor liver morphology with in-depth investigations including not only ultrasonography,but also elastography.

Dietary lysophospholipids improves growth performance and hepatic lipid metabolism of largemouth bass(Micropterus salmoides)

This study was conducted to evaluate the influence of dietary lysophospholipids combined with 1%dietary fish oil reduction on the growth performance and hepatic lipid metabolism of largemouth bass(Micropterus salmoides).Five isonitrogenous feeds were prepared with lysophospholipids at 0%(fish oil group,FO),0.05%(L-0.05),0.1%(L-0.1),0.15%(L-0.15)and 0.2%(L-0.2),respectively.The dietary lipid was 11%in the FO diet and 10%in the other diets.Largemouth bass were fed for 68 d(initial body weight=6.04±0.01 g)with 4 replicates per group and 30 fish per replicate.The results showed that the fish fed diet containing 0.1%lysophospholipids had higher digestive enzyme activity and obtained better growth performance compared to the fish fed FO diet(P<0.05).The feed conversion rate in the L-0.1 group was significantly lower than that in the other groups.Serum total protein and triglyceride contents in L-0.1 group were significantly higher than those in other groups(P<0.05)and the contents of total cholesterol and low-density lipoprotein cholesterol in L-0.1 group were significantly lower than those in FO group(P<0.05).The activity and genes expression of hepatic glucolipid metabolizing enzymes in L-0.15 group were significantly increased compared to those in FO group(P<0.05).Reducing 1%fish oil along with 0.1%lysophospholipids added to the feed could improve the digestion and absorption of nutrients,enhance the activity of liver glycolipid metabolizing enzymes,and thus effectively promote the growth of largemouth bass.