Muscle proximate composition, lipid classes, and fatty acid profiles were also the subject of the investigation. Our study indicates that the addition of macroalgal wracks to the diet of C. idella has no adverse impact on its growth, proximate and lipid composition, antioxidant capacity, or digestive capabilities. Certainly, macroalgal wrack from both sources produced a lower general deposition of fats, while the variety of wrack enhanced liver catalase activity.

We reasoned that the increased liver cholesterol resulting from high-fat diet (HFD) consumption might be countered by the enhanced cholesterol-bile acid flux, which effectively reduces lipid accumulation. This led us to the hypothesis that the enhanced cholesterol-bile acid flux is a physiological adaptation in fish when consuming an HFD. Nile tilapia (Oreochromis niloticus) cholesterol and fatty acid metabolism were investigated following a four- and eight-week regimen of a high-fat diet (13% lipid). Visually healthy Nile tilapia fingerlings, each weighing an average of 350.005 grams, were randomly allocated to four dietary treatments: a 4-week control diet, a 4-week high-fat diet (HFD), an 8-week control diet, or an 8-week high-fat diet (HFD). Fish were studied to determine the effects of short-term and long-term high-fat diet (HFD) on hepatic lipid deposition, health status markers, cholesterol/bile acid ratios, and fatty acid metabolism. The findings from the four-week high-fat diet (HFD) experiment revealed no modification in serum alanine transaminase (ALT) and aspartate transaminase (AST) enzyme levels, along with comparable liver malondialdehyde (MDA) content. Fish receiving an 8-week high-fat diet (HFD) showed a significant rise in the activities of serum ALT and AST enzymes, and an increase in liver MDA. Remarkably elevated total cholesterol levels, primarily cholesterol esters (CE), were seen in the liver of fish fed a 4-week high-fat diet (HFD). This was concurrent with a modest elevation of free fatty acids (FFAs), and similar levels of triglycerides (TG). Molecular analysis of the livers of fish fed a 4-week high-fat diet (HFD) indicated that the observed accumulation of cholesterol esters (CE) and total bile acids (TBAs) was principally a consequence of augmented cholesterol synthesis, esterification, and bile acid synthesis. The protein expression of acyl-CoA oxidase 1 and 2 (Acox1 and Acox2) increased in fish after being fed a high-fat diet (HFD) for four weeks. These enzymes are rate-limiting factors in peroxisomal fatty acid oxidation (FAO) and are vital for transforming cholesterol into bile acids. Eight weeks of a high-fat diet (HFD) led to a remarkable 17-fold elevation in free fatty acid (FFA) content in fish. Importantly, this increase did not correlate with changes in liver triacylglycerol (TBA) levels. This coincided with suppressed Acox2 protein expression and abnormalities in cholesterol and bile acid biosynthesis. Subsequently, the robust cholesterol-bile acid transport mechanism acts as an adaptive metabolic response in Nile tilapia when fed a brief high-fat diet, potentially through the activation of peroxisomal fatty acid oxidation. The adaptive nature of cholesterol metabolism in fish nourished by a high-fat diet is underscored by this finding, and potentially provides new avenues for therapeutic strategies to combat metabolic diseases induced by high-fat diets in aquatic species.

A 56-day experimental research study explored the recommended histidine requirement and its role in shaping protein and lipid metabolism in juvenile largemouth bass (Micropterus salmoides). At commencement, the largemouth bass possessed a weight of 1233.001 grams, and this was followed by the administration of six graduated levels of histidine. Analysis revealed that the inclusion of 108-148% histidine in the diet positively impacted growth parameters, specifically increasing the specific growth rate, final weight, weight gain rate, and protein efficiency rate while concurrently decreasing feed conversion and intake rates. Moreover, the mRNA levels of GH, IGF-1, TOR, and S6 exhibited an escalating pattern initially, subsequently diminishing, mirroring the trajectory of growth and protein content within the overall body composition. As dietary histidine levels increased, the AAR signaling pathway exhibited downregulation of key genes, including GCN2, eIF2, CHOP, ATF4, and REDD1, reflecting the detected increase. Increased dietary histidine caused a reduction in body-wide and liver lipid content via upregulation of mRNA levels for pivotal PPAR signaling pathway genes, encompassing PPAR, CPT1, L-FABP, and PGC1. OD36 Despite this, a rise in dietary histidine levels led to a reduction in mRNA levels for core genes associated with the PPAR signaling cascade, including PPAR, FAS, ACC, SREBP1, and ELOVL2. Hepatic oil red O staining's positive area ratio, together with the plasma's TC content, bolstered the validity of these findings. OD36 The quadratic model, applied to the specific growth rate and feed conversion rate data, determined that juvenile largemouth bass require a histidine intake of 126% of the diet, which equates to 268% of dietary protein. Histidine supplementation, by triggering the TOR, AAR, PPAR, and PPAR signaling pathways, resulted in an increase in protein synthesis, a decrease in lipid synthesis, and an increase in lipid decomposition, offering a fresh nutritional perspective for managing the fatty liver condition in largemouth bass.
The apparent digestibility coefficients (ADCs) of multiple nutrients were assessed in a digestibility trial involving juvenile African catfish hybrids. The experimental diets incorporated defatted black soldier fly (BSL), yellow mealworm (MW), or fully fat blue bottle fly (BBF) meals, combining them with a 70% control diet in a ratio of 30:70. The digestibility study utilized the indirect method, employing 0.1% yttrium oxide as an inert marker. Within a recirculating aquaculture system (RAS), triplicate 1-cubic-meter tanks, holding 75 fish each, were stocked with 2174 juvenile fish, initially weighing 95 grams, and fed to satiation for 18 days. A mean final weight of 346.358 grams was observed for the fish population. Quantitative analyses for dry matter, protein, lipid, chitin, ash, phosphorus, amino acids, fatty acids, and gross energy were carried out on the test ingredients and their corresponding diets. To assess the shelf life of the experimental diets, a six-month storage test was conducted, along with evaluations of peroxidation and microbiological conditions. The ADC values of the test diets presented a statistically considerable divergence (p < 0.0001) from the control group's values for most nutritional components. The BSL diet showcased a substantial advantage in digestibility for protein, fat, ash, and phosphorus, however, it exhibited a disadvantage in digestibility for essential amino acids when compared to the control diet. Statistically significant disparities (p<0.0001) in ADCs were found across practically all nutritional fractions analyzed for the different insect meals. African catfish hybrid digestive processes proved more effective for BSL and BBF than MW, as evidenced by corresponding ADC values consistent with other fish species. The MW meal's lower ADCs were found to be significantly (p<0.05) associated with the substantially increased acid detergent fiber (ADF) levels within the MW meal and diet. A microbiological survey of the feeds revealed mesophilic aerobic bacteria to be strikingly more abundant in the BSL feed—two to three orders of magnitude more—than in the other diets, and their numbers markedly increased during the duration of storage. For African catfish juveniles, BSL and BBF were found to be potentially suitable feed ingredients, with diets containing 30% insect meal preserving their quality during the six-month storage period.

The use of alternative plant-based protein sources in fishmeal-heavy aquaculture diets offers a promising avenue. Over 10 weeks, a feeding experiment evaluated the effects of replacing fish meal with a mixture of plant proteins (a 23:1 ratio of cottonseed meal to rapeseed meal) on growth, oxidative stress, inflammatory reactions, and the mTOR pathway in the yellow catfish, Pelteobagrus fulvidraco. Yellow catfish, weighing approximately 238.01 grams (mean ± SEM) were randomly allocated to 15 indoor fiberglass tanks. Each tank contained 30 fish, and the fish were fed five different diets, all isonitrogenous (44% crude protein) and isolipidic (9% crude fat), varying in the proportion of fish meal replaced by mixed plant protein: 0% (control), 10% (RM10), 20% (RM20), 30% (RM30), and 40% (RM40), respectively. OD36 Across five dietary groups, fish fed the control and RM10 diets generally displayed more robust growth, a higher proportion of protein in their liver tissue, and lower levels of lipids within their livers. A mixed plant protein dietary replacement elevated hepatic gossypol, caused liver damage, and lowered serum concentrations of total essential, total nonessential, and total amino acids. A correlation between higher antioxidant capacity and yellow catfish fed RM10 diets was observed, distinct from the control group. Incorporating a mixed plant protein source into the diet frequently led to the activation of pro-inflammatory pathways and a decrease in mTOR activity. The optimal replacement level of fish meal by mixed plant protein, as revealed by the second regression analysis of SGR against the latter, stands at 87%.

Carbohydrates, the least expensive energy source among the major three nutrients, can reduce feed costs and improve growth performance with appropriate amounts, but carnivorous aquatic animals cannot effectively metabolize them. This investigation focuses on determining the consequences of varying levels of dietary corn starch on glucose absorption capacity, insulin's effects on blood sugar levels, and the maintenance of glucose homeostasis in the Portunus trituberculatus. Swimming crabs, after two weeks of feeding, were starved and analyzed at time points of 0, 1, 2, 3, 4, 5, 6, 12, and 24 hours, respectively, following the starvation. Analysis of the results demonstrated that crabs fed a diet lacking corn starch had lower glucose levels in their hemolymph than crabs fed other diets, and these low hemolymph glucose levels persisted as the sampling time progressed.