Serena Busti

The present study was designed to evaluate the effects of dietary levels of bioactive peptides (BPs) derived from salmon processing by-products on the presence and distribution of peptic cells (oxyntopeptic cells, OPs) and enteric endocrine cells (EECs) that contain GHR, NPY and SOM in the gastric mucosa of European seabass and gilthead seabream. In this study, 27 seabass and 27 seabreams were divided into three experimental groups: a control group (CTR) fed a control diet and two groups fed different levels of BP to replace fishmeal: 5% BP (BP5%) and 10% BP (BP10%). The stomach of each fish was sampled and processed for immunohistochemistry. Some SOM, NPY and GHR-IR cells exhibited alternating “open type” and “closed type” EECs morphologies. The BP10% group (16.8 ± 7.5) showed an increase in the number of NPY-IR cells compared to CTR (CTR 8.5 ± 4.8) and BP5% (BP10% vs. CTR p ≤ 0.01; BP10% vs. BP5% p ≤ 0.05) in the seabream gastric mucosa. In addition, in seabream gastric tissue, SOM-IR cells in the BP 10% diet (16.8 ± 3.5) were different from those in CTR (12.5 ± 5) (CTR vs. BP 10% p ≤ 0.05) and BP 5% (12.9 ± 2.5) (BP 5% vs. BP 10% p ≤ 0.01). EEC SOM-IR cells increased at 10% BP (5.3 ± 0.7) compared to 5% BP (4.4 ± 0.8) (5% BP vs. 10% BP p ≤ 0.05) in seabass. The results obtained may provide a good basis for a better understanding of the potential of salmon BPs as feed ingredients for seabass and seabream.

In recent years, insect meal has attracted increasing interest as an innovative protein source to replace fish meal in feed formulation due to its valuable nutritional profile. This research aimed to compare the effects of different dietary inclusion levels (5, 10, and 15%) of Hermetia illucens (HI) larvae meal on Sparus aurata (initial weight: 98.6 ± 0.6 g) sensorial, technological, and nutritional fillets quality. Fish were fed experimental diets over 113 days. Results showed that the inclusion of defatted HI larvae meal did not induce off-flavours in gilthead sea bream fillets. No significant differences were found in appearance, mouthfeels, and texture, while a difference emerged in the trait ‘cooked chicken breast’ for odour and flavour characteristics. Moreover, fillets’ quality traits and proximate composition analyses performed did not show significant differences between the treatments. The fillets’ fatty acid content showed that higher inclusion of HI meal leads to higher saturated fatty acids content, while no significant difference in polyunsaturated fatty acids was observed among treatments. Results have a positive implication as dietary HI did not negatively affect the fatty acids composition or quality of sea bream fillets.

The aim of the present study was to evaluate the effects on the presence and distribution of oxyntopeptic cells (OPs) and enteroendocrine cells (EECs) expressing GHR, NPY and SOM in the gastric mucosa of European seabass and seabream of dietary levels of bioactive peptides (BPs) obtained from salmon processing by-products (in silico approach). In this study, 27 seabass and 27 seabreams were divided into three experimental groups: a control group (CTR) fed a control diet and two groups fed different levels of BP to replace fishmeal: 5% BP (BP5%) and 10% BP (BP10%). The stomach of each fish was sampled and processed for immunohistochemistry. Some SOM, NPY and GHR-IR cells exhibited alternating “open type” and “closed type” EECs morphologies. In seabream gastric mucosa, the BP10% group (16.8 ± 7.5) showed a significant change in NPY-IR cell number compared to CTR (CTR 8.5 ± 4.8) and BP5% (BP10% vs. CTR P ≤ 0.01; BP10% vs. BP5% P ≤ 0.05). In seabream, SOM-IR cells in the BP 10% diet (16.8 ± 3.5) differed from those in CTR (12.5 ± 5) (CTR vs. BP 10% P ≤ 0.05) and BP 5% (12.9 ± 2.5) (BP 5% vs. BP 10% P ≤ 0.01). In seabass, EEC SOM-IR cells increased at 10 % BP (5.3 ± 0.7) compared to 5 % BP (4.4 ± 0.8) (5 % BP vs. 10 % BP P ≤ 0.05). The results obtained suggest that salmon BPs have a promising impact as circulating ingredients for seabass and seabream.

The current work was designed to assess the effect of feed supplemented with essential oils (EOs) on the histological features in sea bass’s gastric mucosa. Fish were fed three diets: control diet (CTR), HERBAL MIX^® made with natural EOs (N-EOs), or HERBAL MIX^® made with artificial EOs obtained by synthesis (S-EOs) during a 117-day feeding trial. Thereafter, the oxyntopeptic cells (OPs) and the ghrelin (GHR) and somatostatin (SOM) enteroendocrine cells (EECs) in the gastric mucosa were evaluated. The Na⁺K⁺-ATPase antibody was used to label OPs, while, for the EECs, anti-SOM and anti-GHR antibody were used. The highest density of OP immunoreactive (IR) area was in the CTR group (0.66 mm² ± 0.1). The OP-IR area was reduced in the N-EO diet group (0.22 mm² ± 1; CTR vs. N-EOs, p < 0.005), while in the S-EO diet group (0.39 mm² ± 1) a trend was observed. We observed an increase of the number of SOM-IR cells in the N-EO diet (15.6 ± 4.2) compared to that in the CTR (11.8 ± 3.7) (N-EOs vs. CTR; p < 0.05), but not in the S-EOs diet. These observations will provide a basis to advance current knowledge on the anatomy and digestive physiology of this species in relation to pro-heath feeds.