The effects of the dietary administration of two bacterial probiotic strains (Ppd11 and Pdp13) from the Alteromonadaceae family for 60 days, were assessed by measuring growth and feed efficiency, activities of leucine aminopeptidase and alkaline phosphatase and structural changes in the intestine of juvenile Senegalese sole. In addition, the profile of intestinal microbiota was studied by Denaturing Gradient Gel Electrophoresis. Growth and nutrient utilization were significantly higher in fish receiving probiotics than in those fed the control diet. No differences were observed in proximal composition between treatments, though higher lipid muscle content was measured in fish receiving Pdp13. Those fish also exhibited higher activities of AP when compared to Ppd11 and control groups. The profile of intestinal microbiota clearly separated those fish receiving probiotics from those of the control group. Microscopical examination revealed accumulation of lipid droplets in the enterocytes of fish receiving the control diet, but not in those fed on probiotics. Interactions between those structural changes and growth performance are discussed.
In vitro assays simulating the digestion process have been extensively used in the evaluation of the nutritional quality of foods and feeds for humans and terrestrial animals. Such techniques have been comparatively less used in nutrition of aquacultured species, although in recent years the interest in developing alternatives to the conventional in vivo digestibility assays has increased. Using 65 published papers as a reference, this review summarizes the different approaches and configurations used to date in the simulation of the digestion of food by aquatic animals, as well as the main limitations detected in the different methods and the potential advantages derived from their application. Some recommendations are suggested to develop suitable in vitro assays oriented either to the nutritional evaluation of feed ingredients or to get a more detailed knowledge on the interactions among digestive enzymes and feed components.
The hydrolysis of protein in di¡erent animal and plant sources by the intestinal proteases of Senegalese sole (Solea senegalensis) was studied using a combination of an in vitro digestibility assay and the evaluation of the protein fractionation by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). In vitro hydrolysis was performed for 90 min in a closed reactor maintained at constant pH and temperature. Samples of the reaction mixture at di¡erent time intervals were developed in SDS-PAGE gels to evaluate the progressive hydrolysis of the di¡erent protein fractions in each protein source. A numerical value [coe⁄cient of protein degradation (CPD)], which integrates the information obtained after image analysis of the gels, is proposed for comparison among proteins, according to the intensity of the hydrolysis produced by sole proteases. Additionally, the total free amino acid released from proteins was measured during the in vitro assay. Casein, squid meal and soybean concentrate (SBC) proteins showed very similar degradation patterns, with a quick and almost complete proteolysis within the ¢rst minutes of the enzymatic reaction. Fish and krill meals were hydrolysed more progressively. On the contrary, pea meal (PM) and corn gluten meal (CGM) showed scarce changes in their protein pro¢le after 90 min of reaction. For animal protein sources, the ¢nal CPD values ranged from 77.6% to 87.0%, showing not signi¢cant di¡erences. By contrast, PM (30.5%) and CGM (32.3%) presented signi¢cantly lower CPD values (Po0.05) as compared with SBC (90.6%). In general, a linear ¢tting was found between CPD and the release of free amino acids during in vitro protein hydrolysis. The present study provides detailed information, which, combined with the conventional in vitro digestibility studies, may help in the evaluation of di¡erent raw sources according to their protein degradation patterns. This information can be applied directly to estimate the protein nutritional quality of ingredients for Senegalese sole feeds.
Juvenile sea bream were fed on diets containing 0.0, 2.0 or 4.0 g kg À 1 of a soybean trypsin inhibitor (SBTI) for 30 days. The growth performance, total protease activity and intestinal histology were studied after 0, 15 and 30 days of dietary treatment. No signi¢cant di¡erences were found in the weight gain, speci¢c growth rate (SGR) and feed conversion rate in ¢sh fed on inhibitor-supplemented diets when compared with those fed on an inhibitor-free diet. Only the SGR at day 15 decreased signi¢cantly with protease inhibitor inclusion, although this e¡ect was not observed at day 30. In relation to proteolytic activity at day15, the total protease activity in the distal intestine decreased in ¢sh fed on inhibitor-supplemented diets. Zymograms of these extracts showed that the SBTI reduced the intensity of some proteolytic fractions in the distal intestine. A noticeable reduction in the protease activity of the intestinal content in ¢sh fed on the highest level of soybean inhibitor (4.0 g kg) was also observed. However, at day 30, the inhibition e¡ect on these active bands was not detected, and the total protease activity was similar to that in ¢sh fed on an inhibitor-free diet. Histological examination revealed no perceptible di¡erences in the intestinal structure between any of the diet groups. In addition, all ¢sh were maintained under experimentation for 10 more days and fed on an inhibitor-free diet to determine whether the possible e¡ects caused by the protease inhibitor could be reverted. The administration of SBTI-supplemented diets did not a¡ect sea bream growth performance or intestine histology after 30 days, and only a decrease in the total alkaline protease activity was found at day 15.
In the present study, the protective effect of nucleotides over damages induced by the consumption of a diet containing a high amount of vegetable ingredients (560 g kg(-1)) in the intestinal epithelia of the meagre (Argyrosomus regius) was assessed by assays performed with an Ussing-type chamber. Two experimental feeds were prepared including or not a commercial mixture of nucleotides (1 g kg(-1)). Nucleotides significantly enhanced fish growth during the experiment. On the other hand, differences in the integrity and functionality of intestinal epithelia were evidenced by a change in the polarity of intestinal trans-epithelial potential. Samples of fish fed on the control diet showed a preferentially secretory short-circuit current, while those of fish receiving the nucleotide-supplemented diet showed a significantly lower and preferentially absorptive negative current. It is concluded that alterations of intestinal physiology juvenile meagre resulting from the intake of high amounts of plant ingredients could be minimized by nucleotide supplementation.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.