Impact of high dietary cornstarch level on growth, antioxidant response, and immune status in GIFT tilapia Oreochromis niloticus

Appropriate Fat Supplementation in High-Starch Diets Involved in the Modification of Fatty Acids Profile, Amino Acids Composition, and Antioxidant Capacity of Adult Nile Tilapia (Oreochromis niloticus) Muscle

Tilapia industry has faced great challenges due to the replacement of high-quality protein sources by a high proportion of starch. Meanwhile, the level of dietary fat is gradually reduced with the increase of oil price. High starch diets have been proved to have negative effects on flesh quality in previous studies, but the effects of fat remain unclear. The objective of the present study was to ascertain whether fat level is a requisite factor in the flesh quality of adult fish under conditions of high-starch diet feeding. The study involved adult Nile tilapia (Oreochromis niloticus) with an initial body weight (IBW) of 168.58 ± 2.01 g, which were fed a standard (CON) diet, a high-starch-low-fat (HSLF) diet, and a high-starch-moderate-fat (HSMF) diet for 10 weeks. The results demonstrated that the high starch diets significantly decreased the hardness, chewiness, springiness, and gumminess of muscle. HSLF diet led to a significant reduction in the weight gain rate (WGR), accompanied by an increase in crude fat content and a decrease in glycogen content in the muscle. The HSLF diet resulted in a reduction in the levels of polyunsaturated fatty acids (PUFAs), essential amino acids (EAAs), and flavor amino acids (FAAs) in the muscle tissue. Furthermore, it influenced muscle texture by reducing collagen content, fiber density, and sarcomere length. The muscle antioxidant capacity was diminished by affecting the total antioxidant capacity (T-AOC), catalase (CAT) activity, and superoxide dismutase (SOD) activity, as well as the expression levels of related genes (SOD, CAT, and nuclear factor erythroid 2 like 2 (nrf2)). In contrast, the HSMF diet did not have a detrimental impact on growth performance, yet it did result in a significant increase in glycogen content, hydroxyproline (Hyp), PUFAs, EAA, and FAA in muscle tissue. Moreover, the HSMF diet was observed to markedly elevate the antioxidant capacity of the muscle. It can be concluded that high-starch diet can significantly affect flesh quality by affecting the texture and muscle nutrients, as well as decreasing antioxidant capacity. Nevertheless, the inclusion of an adequate quantity of fat may prove an effective means of counteracting these unfavorable outcomes.

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.

High Starch Induces Hematological Variations, Metabolic Changes, Oxidative Stress, Inflammatory Responses, and Histopathological Lesions in Largemouth Bass (Micropterus salmoides)

This study evaluated effects of high starch (20%) on hematological variations, glucose and lipid metabolism, antioxidant ability, inflammatory responses, and histopathological lesions in largemouth bass. Results showed hepatic crude lipid and triacylglycerol (TAG) contents were notably increased in fish fed high starch. High starch could increase counts of neutrophils, lymphocytes, monocytes, eosinophils, and basophils and serum contents of TAG, TBA, BUN, and LEP (p < 0.05). There were increasing trends in levels of GLUT2, glycolysis, gluconeogenesis, and LDH in fish fed high starch through the AKT/PI3K signal pathway. Meanwhile, high starch not only triggered TAG and cholesterol synthesis, but mediated cholesterol accumulation by reducing ABCG5, ABCG8, and NPC1L1. Significant increases in lipid droplets and vacuolization were also shown in hepatocytes of D3-D7 groups fed high starch. In addition, high starch could decrease levels of mitochondrial Trx2, TrxR2, and Prx3, while increasing ROS contents. Moreover, high starch could notably increase amounts of inflammatory factors (IL-1β, TNF-α, etc.) by activating NLRP3 inflammasome key molecules (GSDME, caspase 1, etc.). In conclusion, high starch could not only induce metabolic disorders via gluconeogenesis and accumulation of glycogen, TAG, and cholesterol, but could disturb redox homeostasis and cause inflammatory responses by activating the NLRP3 inflammasome in largemouth bass.

Association between macronutrients intake and liver dysfunction among tuberculosis patients in rural China

BACKGROUND AND OBJECTIVES

Macronutrients play a vital role in liver dysfunction and affect tuberculosis treatment and prognosis. However, macronutrients intake was inadequate for most tuberculosis patients. This study aimed to clarify the associations between macronutrients intake or energy percentages and liver dys-function in tuberculosis patients.

METHODS AND STUDY DESIGN

In this cross-sectional study, 2581 active tu-berculosis patients aged ≥18 years were included from local tuberculosis clinics in Linyi, China. Macronutrients intake and energy percentages were assessed by 24-hour dietary recalls. The concentration of alanine transferase (ALT) or aspartate transaminase (AST) greater than 40 U/L was defined as liver dysfunction. A restricted cubic spline (RCS) was applied to determine the dose-response relationships.

RESULTS

Liver dysfunction was assessed for 14.6% (377 patients) of tuberculosis patients. Higher protein (Q2-Q4 in model 1 and 2) or fat intake and fat-to-energy percentages and lower carbohydrate-to-energy percentages (Q4 in model 1) were associated with a decreased incidence of liver dysfunction (p-trend < 0.05). Among those who were male, normal BMI, or consumed energy <1636 kcal/d, inverse associations between protein or fat intake and the risks of liver dysfunction in models were suggested (p-trend < 0.05). Moreover, J-shaped curves in RCS were evident in liver dysfunction tuberculosis patients with protein or fat intake (p-nonlinearity < 0.05). Conclu-sions: Significant linear associations between macronutrients intake or energy percentages and liver dysfunction prevalence were found only in male, normal BMI, or less energy intake patients. The shapes of liver dysfunction-morbidity differed significantly by macronutrients intake or energy percentage.

High starch diets attenuate the immune function of Micropterus salmoides immune organs by modulating Keap1/Nrf2 and MAPK signaling pathways

Based on their good physiological functions and physical properties, carbohydrates are widely used in fish feed. However, excessive use of carbohydrates such as starch in fish feed may reduce the immunity of the fish and cause a series of health problems. In order to more clearly clarify the effects of different starch levels in feed on the immune organs of Micropterus salmoides, this study took the immune organs as the entry point and explored it from several perspectives, including differences in enzyme activity in plasma, changes in gene expression in immune organs, and resistance to pathogenic bacteria. The results showed that (1) high starch feed activates inflammatory responses in the spleen and head kidney through the MAPK signaling pathway. This leads to a decrease in the number of lymphocytes and weakens the resistance to pathogens; (2) high starch diet affects the antioxidant capacity of the trunk kidney by regulating the Keap1/Nrf2 pathway; (3) There was a strong correlation between gene expression patterns in the head kidney and lysozyme content in plasma. This implies that the high starch diet may regulate lysozyme production by affecting gene expression in the head kidney and further affect immune function. This study helps to reveal the interaction between starch and the immune system and provide scientific basis for the development of reasonable dietary recommendations and disease prevention.

Dietary ARA, DHA, and Carbohydrate Ratios Affect the Immune Status of Gilthead Sea Bream Juveniles upon Bacterial Challenge

This study aims to assess the effects of different dietary n-6/n-3 long-chain polyunsaturated fatty acid ratios and CHO content in the immune response of gilthead seabream. For that purpose, gilthead sea bream juveniles (initial body weight = 47.5 g) were fed for 84 days with four isoproteic (47% crude protein) and isolipidic (18% crude lipids) diets with high (20%) or low (5%) level of gelatinized starch (HS or LS diets, respectively) and included approximately 2.4% ARA or DHA. At the end of the trial, the DHA-enriched groups presented increased red blood cell (RBC) count, hemoglobin, plasmatic nitric oxide (NO) content, and antiprotease and alternative complement activities. The ARA groups had increased thrombocyte count, and plasmatic bactericidal activity against Vibrio anguillarum was lower in the fish fed the ARA/LS diet. After the feeding trial, the fish were challenged with an intraperitoneal injection (i.p.) of killed Photobacterium damselae subsp. piscicida (Phdp) and sampled at 4 and 24 h after the challenge. At 4 h after i.p., the ARA groups presented increased plasma total immunoglobulins (Ig) and bactericidal activity against V. anguillarum. In addition, the fish fed the ARA/LS diet presented lower white blood cell (WBC) and alternative complement activity. At 24 h after i.p., the ARA groups presented increased RBC, WBC, and thrombocyte numbers, total IG, plasma peroxidase activity, and casp3 expression in the distal intestine. The HS groups presented increased plasma NO content and bactericidal activity against Phdp and decreased protease, antiprotease activity, and bactericidal activity against V. anguillarum. In conclusion, high dietary DHA levels seemed to improve the immune status of unchallenged gilthead sea bream juveniles, while high dietary ARA levels improved the fish immune response to a bacterial challenge. The energy provided by dietary starch seems to be important to promote a fast response by the fish immune system after a challenge.

High Starch in Diet Leads to Disruption of Hepatic Glycogen Metabolism and Liver Fibrosis in Largemouth Bass (Micropterus salmoides), Which is Mediated by the PI3K/Akt Signaling Pathway

Due to its special flavour and cheapness, starch is a source of nutrition for humans and most animals, some of whom even prefer to consume large amounts of starchy foods. However, the use of starch by carnivorous fish is limited and excessive starch intake can lead to liver damage, but the mechanism of damage is not clear. Therefore, in this study, two isonitrogenous and isolipid semi-pure diets, Z diet (0% starch) and G diet (22% starch), were formulated, respectively. The largemouth bass (M. salmoides) cultured in fiberglass tanks were randomly divided into two groups and fed the two diets for 45 days. Blood and liver were collected on day 30 and 45 for enzymology, histopathology, ultramicropathology, flow cytometry, and transcriptomics to investigate the damage of high starch on the liver of largemouth bass and its damage mechanism. The results showed that the high starch not affect the growth performance of largemouth bass. However, high starch caused a whitening of the liver and an increase in hepatopancreas index (HSI), aspartate aminotransferase (AST), and alanine aminotransferase (ALT) in the serum. Histopathological observations showed that high starch led to severe vacuolisation, congestion, and moderate to severe necrotizing hepatitis in the liver. The high starch intake led to a significant increase in postprandial blood glucose and insulin in serum of largemouth bass, promoting the synthesis and accumulation of large amounts of hepatic glycogen in the liver, leading to the loss of hepatocyte organelles and inducing liver fibrosis. Meanwhile, high starch induced the production of oxidative stress and promoted apoptosis and necrosis of hepatocytes. Transcriptome analysis revealed that there were 10,927 and 2,656 unique genes in the G and Z groups, respectively. KEGG enrichment analysis showed that 19 pathways were significantly enriched, including those related to glucose metabolism and cell survival. Network mapping based on enrichment pathways and differential expressing genes showed the emergence of a regulatory network dominated by PI3K/Akt signaling pathway. This indicated that the PI3K/Akt signalling pathway plays a very important role in this process, regulating the liver injury caused by high starch. Our results provide a reference for the mechanism of liver injury caused by high starch, and the PI3K/Akt signalling pathway could be a potential therapeutic target for liver injury caused by high starch.

Effects of dietary carbohydrate/lipid ratios on non-specific immune responses, antioxidant capacity, hepatopancreas and intestines histology, and expression of TLR-MAPK/NF-κB signaling pathway-related genes of Procambarus clarkii

To investigate the effects of dietary carbohydrate/lipid (CHO: L) ratios on non-specific immune responses, antioxidant capacity, and expression of TLR-MAPK/NF-κB signaling pathway-related genes of red swamp crayfish (Procambarus clarkii). Four isonitrogenous and isoenergetic diets containing different CHO: L ratios were formulated. The results showed that the group with a CHO: L ratio of 5.94 had better growth performance (P < 0.05). The highest T-AOC, CAT, and SOD activities and the lowest MDA content in hemolymph and hepatopancreas were observed in the group with a CHO: L ratio of 5.94 (P < 0.05). The lowest activities of ALT, AST, ACP, AKP, and ALB in the hemolymph were observed in CHO: L ratio 5.94 group (P < 0.05), while the highest LZM activity, TP, and GLB content were observed in CHO: L 5.94 group (P < 0.05). The highest mRNA expression levels of tlr3, myd88, and mapk3, and the lowest mRNA expression levels of nf-kb α, nf-kb β, nf-kb p105, and traf6 were observed in the CHO: L of 5.94 group (P < 0.05). The highest mRNA expression levels of immune-related genes were observed in the CHO: L of 5.94 group (P < 0.05). Overall, these results indicated that the optimum dietary CHO: L ratio is vital in promoting growth and enhancing antioxidants and immunity to maintain red swamp crayfish's intestinal and hepatopancreas health status. In conclusion, the diets with a CHO:L ratio of 5.94 (approximately 36.23% carbohydrate and 6.10% lipid) is optimal for juvenile red swamp crayfish's physiological condition and health status.