By answering the need for increasing sustainability in aquaculture, the present study aimed to compare growth, gene expression involved in appetite regulation, physical characteristics, and chemical composition of Sparus aurata fed alternative protein sources. Fish were fed ten iso-proteic, iso-lipidic, and isoenergetic diets: a vegetable-based (CV) and a marine ingredient-rich (CF) diet were set as control diets. The others were prepared by replacing graded levels (10, 20 or 40%) of the vegetable proteins in the CV with proteins from a commercial defatted Hermetia illucens pupae meal (H), poultry by-product meal (PBM) singly (H10, H20, H40, P20, P40) or in combination (H10P30), red swamp crayfish meal (RC10) and from a blend (2:1, w:w) of Tisochrysis lutea and Tetraselmis suecica (MA10) dried biomasses. The increase in ghre gene expression observed in MA10 fed fish matched with increased feed intake and increased feed conversion ratio. Besides, the MA10 diet conferred a lighter aspect to the fish skin (p < 0.05) than the others. Overall, no detrimental effects of H, PBM, and RC meal included in the diets were observed, and fish fatty acid profile resulted as comparable among these groups and CV, thus demonstrating the possibility to introduce H, PBM, and RC in partial replacement of vegetable proteins in the diet for Sparus aurata.

Due to the limited application of insect meal in giant freshwater prawn (Macrobrachium rosenbergii) culture, the present study aimed to (i) produce spirulina-enriched full-fat black soldier fly (Hermetia illucens) prepupae meal (HM) and (ii) test, for the first time, two experimental diets characterized by 3% or 20% of fish meal and fish oil replacement with full-fat HM (HM3 and HM20, respectively) on M. rosenbergii post-larvae during a 60-day feeding trial conducted in aquaponic systems. The experimental diets did not negatively affect survival rates or growth. The use of spirulina-enriched HM resulted in a progressive increase in α-tocopherol and carotenoids in HM3 and HM20 diets that possibly played a crucial role in preserving prawn muscle-quality traits. The massive presence of lipid droplets in R cells in all the experimental groups reflected a proper nutrient provision and evidenced the necessity to store energy for molting. The increased number of B cells in the HM3 and HM20 groups could be related to the different compositions of the lipid fraction among the experimental diets instead of a nutrient absorption impairment caused by chitin. Finally, the expression of the immune response and stress markers confirmed that the experimental diets did not affect the welfare status of M. rosenbergii post-larvae.

This study compared the nutrient-energy retention, digestive function, growth performance, and welfare of rainbow trout (ibw 54 g) fed isoproteic (42%), isolipidic (24%), fishmeal-free diets (CV) over 13 weeks. The diets consisted of plant-protein replacement with graded levels (10, 30, 60%) of protein from poultry by-product (PBM) and black soldier fly H. illucens pupae (BSFM) meals, either singly or in combination. A fishmeal-based diet was also tested (CF). Nitrogen retention improved with moderate or high levels of dietary PBM and BSFM relative to CV (p < 0.05). Gut brush border enzyme activity was poorly affected by the diets. Gastric chitinase was up-regulated after high BSFM feeding (p < 0.05). The gut peptide and amino acid transport genes were differently regulated by protein source and level. Serum cortisol was unaffected, and the changes in metabolites stayed within the physiological range. High PBM and high BSFM lowered the leukocyte respiratory burst activity and increased the lysozyme activity compared to CV (p < 0.05). The BSFM and PBM both significantly changed the relative percentage of lymphocytes and monocytes (p < 0.05). In conclusion, moderate to high PBM and BSFM inclusions in fishmeal-free diets, either singly or in combination, improved gut function and nutrient retention, resulting in better growth performance and the good welfare of the rainbow trout.

RESUMO: Desmama é uma fase crítica na vida do suíno devido a separação materna e a introdução de uma dieta seca. A termografia infravermelha medida na região ocular se mostra como um indicador confiável para a condição de estresse pontual de suínos. O objetivo deste estudo foi determinar a relação entre medidas de termografia infravermelha da superfície ocular e de cortisol em situações de estresse em leitões na pós desmama. Foram avaliados 66 leitões, uma vez por semana, durante sete semanas, em dois períodos do dia (7h e 15h) com medidas de temperatura superficial ocular, temperatura superficial do dorso e amostras de saliva para determinação de cortisol salivar. A análise estatística contemplou os efeitos fixos de semana e período do dia e sua interação e correlações de Pearson para relação entre termografia ocular, temperatura superficial e cortisol a 5% de significância. Cortisol salivar não diferiu entre os períodos, mas foi superior nas três primeiras semanas após o desmame (P<0,05). Nas duas primeiras semanas após a desmama o cortisol apresentou correlação alta e positiva (P<0,05) com a temperatura ocular máxima (0,89) e a temperatura superficial do dorso (0,80). As duas temperaturas superficiais apresentaram uma associação moderada positiva (r=0,41; P<0,0001) durante todo o período experimental. Este estudo destaca que a temperatura de superfície ocular obtida por meio da termografia infravermelha pode ser um indicador de temperatura de superfície corporal e estado de bem-estar de leitões em fase de creche, além de ser um método não invasivo e de rápida mensuração. Entretanto, mais pesquisas são necessárias para aprofundar a relação entre temperatura ocular e cortisol durante estresse crônico.