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The influence of different diet formulations during gonadal maturation on reproductive efficiency and embryo quality in Atlantic salmon was investigated. Four diets were compared: Diet 1 contained exclusively marine-origin protein and lipid ingredients, Diet 2 involved substituting 65% of the protein and 51% of the lipid by terrestrial animal and vegetable sources, Diets 3 and 4 were commercial diets. The results showed a higher number of spawned females in the groups of fish fed with diets 1 (73.3%) and 2 (66.7%) than those fed with diets 3 (53.3%) and 4 (50%). Spawning weight and total fecundity did not differ between diets, but a strong correlation was found between these variables, independent of diet. There were no significant differences in zootechnical parameters, but the groups of fish fed the commercial diets tended to have greater weight and length. Oocyte diameter did not differ, but percent hydration was statistically different between groups fed diets 2 and 3. Although there was no difference in embryonic malformations between diets, the presence of microphthalmia correlated negatively with oocyte diameter and percent hydration in embryos obtained from the group of fish fed with Diet 3. Blastomere symmetry and survival at 280 ATU showed statistical differences between diets 3 and 4. Using high-nutritional-value marine ingredients (Diet 1) during gonadal maturation improves reproductive performance in female Atlantic salmon. Enhancing fish broodstock nutrition through targeted research can optimize reproductive success, increase yields, and promote sustainable aquaculture practices. • Diet composition has effects on reproduction in Atlantic salmon. • Marine ingredients optimized maturation rates enhancing reproductive efficiency. • Feeding strategies during gonadal maturation improve rate and spawning timing. [ABSTRACT FROM AUTHOR]

Abstract The use of vegetable ingredients may alter the mineral balance of feeds for gilthead seabream (Sparus aurata) due to the differences in mineral composition between marine and vegetable ingredients. Whereas seabream fed low levels of zinc (Zn) and manganese (Mn) may present reduced growth and performance, as well as alterations in mineral deposition and oxidative stress resistance, information on the type of sources of these two minerals is almost inexistent. In the present study, vegetable meal and oil (VM/VO) based diets were formulated including the target minerals, zinc (Zn) and manganese (Mn) in two different delivery forms, oxides and chelated to amino acids. Gilthead seabream of 8.2g were fed one of five different diets containing either non mineral supplementation, Zn and Mn oxides, amino acid chelates and their combinations. During the experimental period, fish fed Zn oxide presented higher growth, a higher deposition of protein and lower lipid contents in whole body, whereas there was an increase in whole body TBARs and up-regulation of CuZnsod in fish fed diets supplemented with amino acids chelated Zn. Highlights • Dietary mineral uptake varies depending on the source used. This study aims to overcome the shortcomings of other studies regarding mineral-specific effects in Sparus aurata. • Zn and Mn supplementation improve seabream growth, body composition and mineral retention when gilthead seabream are fed diets containing high levels of plant ingredients • Zn oxide improved growth, feed efficiency, lipid and protein deposition and oxidative status related parameters. The effects were not so clear for the Mn sources [ABSTRACT FROM AUTHOR]

Substituting fishmeal (FM) with vegetable meal (VM) can markedly affect the mineral composition of feeds, and may require additional mineral supplementation. Their bioavailability and optimal supplementation levels depend also on the form of delivery of minerals. The aim of the study was to determine the effect of different delivery forms of three major trace elements (Zn, Mn and Se) in a marine teleost. Gilthead sea bream juveniles of 22.5 g were fed a VM-based diet for 12 weeks that was either not supplemented with these minerals or supplemented with inorganic, organic, or encapsulated inorganic forms of minerals in triplicate and compared to a FM-based diet. Our results showed that mineral delivery form significantly affected the biochemical composition and morphology of posterior vertebrae. Supplementation of VM-based diets with inorganic forms of the target minerals significantly promoted growth, increased the vertebral weight and content of ash and Zn, enhanced bone mineralization and affected the vertebral shape. Conversely, encapsulation of inorganic minerals reduced fish growth and vertebral mineral content, whereas supplementation of organic minerals, enhanced bone osteogenesis by upregulating bone morphogenetic protein 2 (bmp2) gene and produced vertebrae with a larger length in relation to height. Furthermore, organic mineral forms of delivery downregulated the expression of oxidative stress related genes, such as Cu/Zn superoxide dismutase (Cu/Zn sod) and glutathione peroxidase 1 (gpx-1), suggesting thus that dietary minerals supplemented in the organic form could be reasonably considered more effective than the inorganic and encapsulated forms of supply.

Substituting fishmeal (FM) with vegetable meal (VM) can markedly affect the mineral composition of feeds, and may require additional mineral supplementation. Their bioavailability and optimal supplementation levels depend also on the form of delivery of minerals. The aim of the study was to determine the effect of different delivery forms of three major trace elements (Zn, Mn and Se) in a marine teleost. Gilthead sea bream juveniles of 22.5 g were fed a VM-based diet for 12 weeks that was either not supplemented with these minerals or supplemented with inorganic, organic, or encapsulated inorganic forms of minerals in triplicate and compared to a FM-based diet. Our results showed that mineral delivery form significantly affected the biochemical composition and morphology of posterior vertebrae. Supplementation of VM-based diets with inorganic forms of the target minerals significantly promoted growth, increased the vertebral weight and content of ash and Zn, enhanced bone mineralization and affected the vertebral shape. Conversely, encapsulation of inorganic minerals reduced fish growth and vertebral mineral content, whereas supplementation of organic minerals, enhanced bone osteogenesis by upregulating bone morphogenetic protein 2 ( bmp2) gene and produced vertebrae with a larger length in relation to height. Furthermore, organic mineral forms of delivery downregulated the expression of oxidative stress related genes, such as Cu/Zn superoxide dismutase (Cu/Zn sod ) and glutathione peroxidase 1 ( gpx-1 ) , suggesting thus that dietary minerals supplemented in the organic form could be reasonably considered more effective than the inorganic and encapsulated forms of supply., Competing Interests: Kristin Hamre is an Academic Editor for PeerJ. Vasileios Karalazos is an employee of BioMar Hellenic SA, Volos, Greece.