A 120-day experiment investigated the new organic raw materials for Gilthead seabream (Sparus aurata) feeding on growth, nutritional parameters, digestibility, and histology. An organic control diet (CON) and three diets with 100% organic raw materials—the rest of rainbow trout, visceral Iberian pig, and insects as a protein source (TRO, IBE, and INS)—were tested. After the experiment, growth, nutritional parameters, digestibility, and histology were measured. The CON diet-fed seabream obtained the highest weight; there was no difference between the experimental diets. The crude protein content was the highest in seabream fed the TRO and INS diets. Crude fat was the highest value observed in the CON diet. High digestibility was observed in seabream-fed IBE and INS diets. Except for EAA methionine (Met), there were no static differences in retention efficiency. The diet with the highest hydrolysis rate was IBE. Diet differences were significant but had the typical healthy liver morphology of seabream. Seabream fed on the TRO and INS diets had shorter distal gut measurements. In conclusion, the full substitution of fishmeal with organic raw materials, including rainbow trout remains, Iberian pig viscera, and insects, offers several benefits in terms of digestibility, histology, and growth performance and may help improve sustainable and healthy aquaculture practices.

The use of organic ingredients as a source of protein in aquaculture diets has gained significant attention due to the growing demand for organic seafood products. This study aimed to evaluate the potential for the use of organic ingredients as protein sources in the diet of juvenile organic seabass (Dicentrarchus labrax). A total of 486 juvenile seabass with an average weight of 90 g were fed six diets containing varied organic proteins. The control group (CON) was fed a diet with conventional fishmeal from sustainable fisheries as the primary protein source. The other five groups were fed diets with different compositions: organic Iberian pig meal byproduct (IB diet), a combination of organic Iberian pig meal byproduct and insect meal (IB-IN diet), a mix of organic Iberian pig meal byproduct and organic rainbow trout meal byproduct (IB-TR diet), a blend of organic rainbow trout meal byproduct and insect meal (TR-IN), and a mixed diet containing all of these protein sources (MIX diet). Over a 125-day feeding trial, growth performance, feed utilisation, feed digestibility, and histological parameters were assessed. The results showed that the fish fed the control diet had the highest final weight and specific growth rate, followed by the fish fed the TR-IN and IB-TR diets. The IB-TR diet had the highest apparent digestibility coefficients (ADCs) for protein, while the TR-IN diet had the lowest. Histological analysis revealed that fish fed the control diet had the largest nucleus diameter and hepatocyte diameter. Use of IN seems to penalise performance in several ways. Fish fed diets containing insect meal grew less, and those diets had lower digestibility. Fish fed the TR and IB diets grew at rates near that of the control, and the feed had acceptable digestibility.

Silymarin and L-carnitine are individually used in fish diets, yet whether they exert interactive or additive effects when combined remains unclear. This study aimed to investigate the individual and combined impacts of dietary silymarin (S), L-carnitine (LC), and their combination (S + LC) on growth performance, digestive enzyme activity, antioxidant status, immune response, and gene expression in Nile tilapia. A total of 360 fish (initial body weight: 10.01 ± 0.03 g) were randomly allocated into 12 fiberglass tanks (30 fish/tank) and fed one of four diets for 84 days: control (basal diet), S (850 mg/kg), LC (500 mg/kg), and S + LC (425 mg/kg S + 250 mg/kg LC). Fish fed S and S + LC diets exhibited significantly higher final body weight, weight gain, and specific growth rate (SGR), along with improved feed conversion ratio (FCR) compared to the control (p < 0.05). All supplemented groups exhibited enhanced digestive enzyme activities (amylase, lipase, protease), with the S + LC group showing the highest values. Serum biochemical profiles revealed increased total protein and globulin and reduced glucose and cortisol levels. Innate immune responses (IgM, lysozyme activity, NBT%, and bactericidal activity) were significantly elevated, especially in the S + LC group. Antioxidant enzyme activities (SOD, CAT, GPx) increased, while malondialdehyde (MDA) levels declined. Gene expression analysis showed significant upregulation of IGF-1, IFNA-1, SOD, CAT, and Gsr, with the greatest expression in the S + LC group. These findings indicate that dietary silymarin and L-carnitine, particularly when provided together, produced complementary and enhanced effects on growth, immune competence, antioxidant capacity, and gene regulation in Nile tilapia.

This study examined how eco-organic feed affects the growth performance, nutrient efficiency, feed utilisation, and body composition of gilthead seabream. Six different diets were tested, including a control diet (CONT) without organic ingredients and four diets with 100% organic ingredients: trout (TRO), seabass (SBS), poultry (POU), and mix (MIX), along with a control organic diet (ORG) containing organic ingredients and 30% fishmeal. The experiment lasted 70 days, and the fish were fed twice a day, starting with an initial weight of 60.5 g. The results showed that the highest growth rates were observed in fish fed the ORG and CONT diets containing fishmeal. Conversely, the POU diet resulted in the lowest growth rate, survival rate, and highest value for feed conversion ratio (FCR). Almost all essential amino acid efficiency values were high in fish fed the ORG and CONT diets. Still, significant differences were noted in the retention efficiency of fatty acids across all diets. The retention efficiency was higher in the CONT diet, followed by the ORG diet. However, the economic conversion rate was lower for CONT, SBS, TRO, and MIX. Overall, using organic diets of animal origin impacted the growth performance of gilthead seabream, but it is still a promising approach.

The use of eco-organic ingredients as a source of protein in aquaculture diets needs important attention due to the growing demand for organic seafood products. The present study evaluated the effects of fish meal substitution by different organic ingredients on the growth, body composition, retention efficiency, enzyme activity, and nutrient digestibility of white shrimp Penaeus vannamei. The four dietary formulations tested were formulated with organic ingredients and the fish meal was replaced by the following organic protein meals: Iberian pig viscera meal (PIG), trout by-product meal (TRO), insect meal (FLY), and organic vegetable meal (WHT), in addition to a control diet (CON) that included 15% fish meal. A growth trial was carried out for 83 days, raising 1 g shrimp to commercial size (20 g). Shrimp were stocked at 167 shrimp/m³ (15 individuals per 90 L tank). The results showed that the growth obtained by shrimp fed with TRO (19.27 g) and PIG (19.35 g) were similar in weight gain to the control diet (20.76 g), while FLY (16.04 g) and WHT (16.73 g) meals resulted in a significant lower final weight. The FLY diet showed significantly lower protein digestibility (68.89%) compared to the CON, PIG, TRO, and WHT diets, and significantly higher trypsin activity (0.17 mU/g) compared to shrimp fed with the PIG, TRO, and WHT diets. Shrimp fed with WHT have a significantly lower body weight percentage of protein (19.69%) than shrimp fed with the WHT and TRO diets, and some significant differences in dietary aminoacidic levels affecting amino acid body composition. These results indicate that Iberian pig viscera and trout by-product meal can successfully replace fish meal in Pacific white shrimp aquaculture.