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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.

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.

In this paper, we consider an equivalence relation on the space $AP(\mathbb {R},X)$ of almost periodic functions with values in a prefixed Banach space X. In this context, it is known that the normality or Bochner-type property, which characterizes these functions, is based on the relative compactness of the family of translates. Now, we prove that every equivalence class is sequentially compact and the family of translates of a function belonging to this subspace is dense in its own class, i.e., the condition of almost periodicity of a function $f\in AP(\mathbb {R},X)$ yields that every sequence of translates of f has a subsequence that converges to a function equivalent to f. This extends previous work by the same authors on the case of numerical almost periodic functions.

The present study was conducted to investigate the effects of dietary fish oil replacement with a mixture of vegetable oils and probiotic supplementation on plasma biochemical parameters, oxidative stress, and antioxidant ability of Seriola dumerili. Specimens with an initial weight of 175 g were used. Four feeds were formulated with 0% (FO-100), 75% (FO-25), and 100% (FO-0 and FO-0+ with the addition of Lactobacillus probiotics) substitution of fish oil with a mixture of linseed, sunflower, and palm oils. After 109 days, no significant differences were observed in the activity of antioxidant enzymes in the liver, foregut, and hindgut, only glucose-6-phosphate dehydrogenase activity in the liver was higher in the fish fed the FO-100 diet than in those fed the FO-0 diet. No significant differences were observed in the total, reduced, and oxidized glutathione and the oxidative stress index in the liver. In addition, lipid peroxidation in the liver and red muscle values were higher in the fish fed the FO-100 diet than in the fish fed the FO-0+ diet, however, the foregut of the fish fed the FO-100 diet presented lower values than that of the fish fed the FO replacement diet, with and without probiotics. There were significant differences in cholesterol levels in the FO-100 group; they were significantly higher than those observed with the fish diets without fish oil. To sum up, fish oil can be replaced by up to 25% with vegetable oils in diets for Seriola dumerili juveniles, but total fish oil substitution is not feasible because it causes poor survival. The inclusion of probiotics in the FO-0+ diet had no effects on the parameters measured.

[EN] Fish (175 g of initial weight) were fed in triplicated groups with four diets formulated by 0% (FO 100), 75% (FO 25) and 100% (with and without probiotics, FO 0 and FO 0+) of fish oil replacement consisting of a mixture of linseed, sunflower and palm oils. After 109 days, growth and nutritional parameters were not affected by the treatment; however, fish fed with 0% of fish oil showed the lowest survival rate and without differences between the same diet with probiotics. As for biometric parameters, significant differences in the viscerosomatic index (VSI) were observed between fish fed the FO 0+ diet and the FO 100 and FO 25 diets. Results obtained from histological analysis did not detect inflammation in gut samples, while liver samples showed a remarkable steatosis in all four treatments. Total fish oil replacement produced a significant difference in the width of the lamina propria. The dietary inclusion of probiotics in the FO 0+ diet seems to favour a recovery of intestine histology. In addition, as fish oil substitution increased, the width of the lamina propria also increased. In conclusion, it is possible to affirm that the four diets administrated toSeriola dumerilidid not compromise the correct development of the animals., The financial support for this study was provided by the "Conselleria de Educacio, Cultura i Esport" of Valencian government (Reference: AICO/2015/123). We also acknowledge David Harry Rhead for their English revision.

[EN] The apparent digestibility coefficients (ADCs) of dry matter, crude protein, crude lipid, and amino acids in fish, krill, squid, meat, defatted krill, soybean, wheat gluten, wheat, camilina, pea, sunflower, and fava bean meals were determined for juvenile Seriola dumerili. The results showed that the ADC of dry matter for yellowtail ranged from 57.7 to 87.2% for animal ingredients and from 42.2 to 82.2% for plant ingredients. An ADC of protein exceeding 90% was observed in fishmeal, while camilina meal and fava bean meal presented the lowest values. Pea meal presented the lowest lipid ADC (83.5%). The availabilities were generally higher in animal ingredients than those in vegetal ones. Except camilina and fava bean meal, the other ingredients appear to be favorable for S. dumerili diets, especially the ones from animal sources. Lower case chemical score values (minimum value from amino acid ratios [AARs]) were obtained in some vegetal ingredients (14¿18%), while the highest ones were observed in marine ingredients (69¿88%). According to Oser's Index, the most balanced protein for yellowtail with regard to essential amino acids was in krill, defatted krill, and fishmeal (92¿96%). So, animal sources are suitable as protein ingredients, but they could be enhanced through some essential amino acid supplementation., This project was financed by the “Ministerio de Ciencia e Innovación” (reference AGL2011-30547-C03).

The authors wish to draw the attention to a mistake which appears in the proof of Proposition 3 of the above quoted paper [4].

[EN] The present study evaluates the effect of dietary barley, based on its potential stress-relieving properties, on rainbow trout under acute stress challenge (hypoxia and crowding) and their recovery. Diets were formulated containing increasing barley concentrations (0, 4, 8, 16, 32%). Cortisol on plasma and fin, glucose and lactate plasma levels and malondialdehyde (MDA) in muscle were determined under normoxia before the stress test (basal levels), 30 min after the acute stress challenge and also during normoxia recovery (6 and 12 h after the stress). Results showed that at basal levels the inclusion of barley had no influence on cortisol, glucose nor on lactate values. After 30 min from the stress challenge, there was a significant increase in cortisol, glucose and lactate concentration in fish of all groups. Plasma cortisol showed the lowest levels in fish fed with diets at a medium (8%) of barley concentration and returned to basal levels 6 h after the stress stimulus with no differences between diets. Glucose values showed a less clear tendency 30 min after the stress challenge with lower levels in the control group, fish fed with 8% and 32% of barley in the diets and returned to basal levels in almost all the groups only 12 h after the stress challenge. Lactate showed the same trend as with glucose after the stress challenge but it returned to basal levels in 6 h. Interestingly, there was a significant decrease of lipid oxidation (MDA) in muscle soon after the stress test of fish fed with the highest barley levels. The present results suggest a potential positive effect of dietary barley on trout stress response., This work has been co-funded with FEDER and INIA funds. Julia Pinedo has been granted with the FPI-INIA grant number 21 (call 2012, BOE-2012-13337).

[EN] The present study compares a control diet to four experimental diets, in which two red beet (14% and 28%) and two betaine levels (0.9% and 1.63%) were incorporated in rainbow trout diets according to a factorial design. The effects of the inclusion of different red beet and betaine concentrations on fatty acid (FA) profile, lipid peroxidation, and antioxidant activity on rainbow trout fillets were investigated. Although no significant differences were observed with the control group, results indicated that red beet and betaine improved fish fillet FA profile, producing an increase in polyunsaturated FAs, mainly docosahexaenoic acid. Higher red beet and betaine concentrations increased flavonoid and phenolic content in the diets; however, no effects were observed for the antioxidant properties of rainbow trout fillets., This work was carried out with funding from INIA and ITACyL, and cofounded by FEDER funds. Julia Pinedo has been granted with the FPI-INIA grant number 21 (call 2012, BOE-2012-13337).