Fortifying fish feeds with bioactive compounds, such as enzymes and antioxidants, has been an ado... more Fortifying fish feeds with bioactive compounds, such as enzymes and antioxidants, has been an adopted strategy to improve feed nutritional quality and sustainability. However, feed additives can lose activity/effectiveness during pelleting and storage processes. This work aimed to monitor functional activity stability in feeds supplemented with a bioactive extract, including cellulases, xylanases, and antioxidants. This bioactive extract (FBE) was produced by Aspergillus ibericus under solid-state fermentation of olive mill and winery by-products. Two isoproteic and isolipidic diets were formulated and unsupplemented or supplemented with lyophilized FBE (0.26% w/w). Both diets were stored at room temperature (RT) or 4 °C for 4 months. Results showed that feed storage at 4 °C enhanced the stability of the enzymes and cellulase was more stable than xylanase. Compared to RT, storage at 4 °C increased cellulase and xylanase half-life by circa 60 and 14%. Dietary FBE supplementation incr...
The effect of dietary short-chain fructooligosaccharides (scFOS) incorporation on growth, feed ut... more The effect of dietary short-chain fructooligosaccharides (scFOS) incorporation on growth, feed utilization, body composition, plasmatic metabolites and liver activity of key enzymes of lipogenic and amino acid catabolic pathways was evaluated in gilthead sea bream reared at 18 and 25 °C. Four practical diets containing plant ingredients and fish meal (50:50) as protein sources and supplemented with 0, 0.1, 0.25 and 0.5 % scFOS were fed to triplicate groups of fish for 8 weeks. Growth performance, feed efficiency and nitrogen retention were higher at 25 °C. In fish reared at 18 °C, there was a positive correlation between dietary scFOS concentration and growth. At 18 °C, liver glycogen was higher in fish fed the control diet, while at 25 °C it was higher in fish fed the 0.5 % scFOS diet. Plasma cholesterol LDL was lower in fish fed 0.25 % scFOS diet, and in fish reared at 18 °C plasma glucose was higher in fish fed the 0.1 % scFOS diet. Glucose 6-phosphate dehydrogenase, fatty acid synthetase and aspartate aminotransferase (ASAT) activities were higher in fish reared at 18 °C, whereas alanine aminotransferase activity was higher in fish reared at 25 °C. scFOS affected ASAT activity, which was lower in fish fed 0.25 % scFOS diet. Although, scFOS seemed to have no major effects on gilthead sea bream metabolism, the positive correlation between dietary prebiotic incorporation and growth at 18 °C indicates a beneficial effect of scFOS in fish reared at low temperatures.
ABSTRACT The objective of this study was to evaluate the potential of free amino acids to replace... more ABSTRACT The objective of this study was to evaluate the potential of free amino acids to replace protein-bound amino acids in diets for Solea senegalensis juveniles. For this purpose, fish with 4.26 g mean initial weight were fed during 55 days with diets containing 500 g kg−1 protein and 100 g kg−1 lipid, based on fish meal and fish oil as main protein and lipid sources (control diet), or diets where 20%, 35% and 50% of fish meal were replaced by crystalline amino acids, using L-lysine HCl as lysine source. To access the efficiency of the crystalline lysine source, another diet was formulated with 35% fish meal replacement but using L-lysine sulphate instead of L-lysine HCl as lysine source. Overall, growth performance, feed utilization, nutrient retention, whole-body and amino acid composition did not show significant differences among groups. In conclusion, up to 50% protein-bound amino acids can be replaced by crystalline amino acids in diets for Senegalese sole juveniles without negative effects in fish performance. Additionally, it was shown that L-lysine sulphate and L-lysine-HCl may be used interchangeably by Senegalese sole juveniles, with the potential economic benefits involved.
Meagre (Argyrosomus regius) belongs to the family Sciaenidae and is a promising candidate for Med... more Meagre (Argyrosomus regius) belongs to the family Sciaenidae and is a promising candidate for Mediterranean aquaculture diversification. As a relatively recent species in aquaculture, the physiological consequences of the immune system activation in meagre are understudied. Spleen, as a primary lymphoid organ has an essential role in meagre immune and inflammatory responses. In this study, we have evaluated the in vivo effects of lipopolysaccharide (LPS) on the spleen transcriptome of meagre by RNA-seq analysis at 4 and 24 h after injection.
Bacillus spp. are well known for their probiotic properties. Hence, the long-term feeding of Baci... more Bacillus spp. are well known for their probiotic properties. Hence, the long-term feeding of Bacillus spp. strains to different fish species has been proved to confer beneficial effects regarding growth or pathogen resistance, among others. However, whether these strains could function as mucosal adjuvants, up-regulating immune responses after a single administration, has not yet been investigated in fish. Thus, in the current work, we have performed a series of experiments in rainbow trout (Oncorhynchus mykiss) aimed at establishing the potential of two Bacillus subtilis spore-forming strains, designated as ABP1 and ABP2, as oral adjuvants/immunostimulants. As an initial step, we evaluated their transcriptional effects on the rainbow trout intestinal epithelial cell line RTgutGC, and in gut tissue explants incubated ex vivo with the two strains. Their capacity to adhere to RTgutGC cells was also evaluated by flow cytometry. Although both strains had the capacity to modulate the transcription of several genes related to innate and adaptive immune responses, it was the ABP1 strain that led to stronger transcriptional effects, also exerting a higher binding capacity to intestinal epithelial cells. Consequently, we selected this strain to establish its effects on splenic B cells upon in vitro exposure as well as to determine the transcriptional effects exerted in the spleen, kidney, and gut after a single oral administration of the bacteria. Our results showed that B. subtilis ABP1 had the capacity to modulate the proliferation, IgM secreting capacity and MHC II surface expression of splenic B cells. Finally, we confirmed that this strain also induced the transcription of genes involved in inflammation, antimicrobial genes, and genes involved in T cell responses upon a single oral administration. Our results provide valuable information regarding how B. subtilis modulates the immune response of rainbow trout, pointing to the usefulness of the ABP1 strain to design novel oral vaccination strategies for aquaculture.
Abstract The effect of dietary digestible protein to digestible energy (DP/DE) ratio on the growt... more Abstract The effect of dietary digestible protein to digestible energy (DP/DE) ratio on the growth performance and metabolic responses of Nile tilapia juveniles was evaluated. Five experimental diets were formulated with increasing DP/DE ratio (13.2, 15.5, 18.4, 20.0, and 22.6 mg kJ−1) and fed to eight replicates of Nile tilapia (initial body weight of 9.3 g) for 110 days. The apparent digestibility coefficients of the diets were determined in a parallel trial. Digestibility coefficients of dry matter, crude protein, and crude energy linearly decreased with increasing dietary P/E ratios. A quadratic effect of dietary DP/DE ratio on growth performance was observed, and maximum weight gain (g kg−1 day−1) or daily growth increment was attained with a dietary DP/DE ratio of 16.5 and 17.2 (mg kJ−1), respectively. Feed intake and energy retention (kJ ABW kg−1 day−1) linearly decreased, and feed efficiency linearly increased with increased dietary DP/DE ratio. The increase of dietary DP/DE ratio decreased the whole body, muscle, hepatic, and visceral lipid content and increased the fillet yield. The decrease of dietary DP/DE linearly increased nitrogen retention (% N intake) and whole-body lipid deposition through the reduction of amino acid catabolism (GDH and ALAT) and gluconeogenesis (FBPase) related enzymes and the increase of glycolysis (GK and HK) and lipogenesis- (G6PDH and ME) related enzymes. In conclusion, a dietary DP/DE ratio of 16.5–17.2 mg kJ−1 promoted the maximum growth performance of Nile tilapia juveniles. However, further studies are required to evaluate if a fine-tuning of the protein amino acid profile would allow a further reduction of the optimum dietary DP/DE ratio. Metabolic response to the decrease in dietary DP/DE levels suggested activation of glycolysis and lipogenesis and inhibition of amino acid catabolism and gluconeogenesis, highlighting the high capacity of Nile tilapia for metabolic utilization of dietary carbohydrates.
Fortifying fish feeds with bioactive compounds, such as enzymes and antioxidants, has been an ado... more Fortifying fish feeds with bioactive compounds, such as enzymes and antioxidants, has been an adopted strategy to improve feed nutritional quality and sustainability. However, feed additives can lose activity/effectiveness during pelleting and storage processes. This work aimed to monitor functional activity stability in feeds supplemented with a bioactive extract, including cellulases, xylanases, and antioxidants. This bioactive extract (FBE) was produced by Aspergillus ibericus under solid-state fermentation of olive mill and winery by-products. Two isoproteic and isolipidic diets were formulated and unsupplemented or supplemented with lyophilized FBE (0.26% w/w). Both diets were stored at room temperature (RT) or 4 °C for 4 months. Results showed that feed storage at 4 °C enhanced the stability of the enzymes and cellulase was more stable than xylanase. Compared to RT, storage at 4 °C increased cellulase and xylanase half-life by circa 60 and 14%. Dietary FBE supplementation incr...
The effect of dietary short-chain fructooligosaccharides (scFOS) incorporation on growth, feed ut... more The effect of dietary short-chain fructooligosaccharides (scFOS) incorporation on growth, feed utilization, body composition, plasmatic metabolites and liver activity of key enzymes of lipogenic and amino acid catabolic pathways was evaluated in gilthead sea bream reared at 18 and 25 °C. Four practical diets containing plant ingredients and fish meal (50:50) as protein sources and supplemented with 0, 0.1, 0.25 and 0.5 % scFOS were fed to triplicate groups of fish for 8 weeks. Growth performance, feed efficiency and nitrogen retention were higher at 25 °C. In fish reared at 18 °C, there was a positive correlation between dietary scFOS concentration and growth. At 18 °C, liver glycogen was higher in fish fed the control diet, while at 25 °C it was higher in fish fed the 0.5 % scFOS diet. Plasma cholesterol LDL was lower in fish fed 0.25 % scFOS diet, and in fish reared at 18 °C plasma glucose was higher in fish fed the 0.1 % scFOS diet. Glucose 6-phosphate dehydrogenase, fatty acid synthetase and aspartate aminotransferase (ASAT) activities were higher in fish reared at 18 °C, whereas alanine aminotransferase activity was higher in fish reared at 25 °C. scFOS affected ASAT activity, which was lower in fish fed 0.25 % scFOS diet. Although, scFOS seemed to have no major effects on gilthead sea bream metabolism, the positive correlation between dietary prebiotic incorporation and growth at 18 °C indicates a beneficial effect of scFOS in fish reared at low temperatures.
ABSTRACT The objective of this study was to evaluate the potential of free amino acids to replace... more ABSTRACT The objective of this study was to evaluate the potential of free amino acids to replace protein-bound amino acids in diets for Solea senegalensis juveniles. For this purpose, fish with 4.26 g mean initial weight were fed during 55 days with diets containing 500 g kg−1 protein and 100 g kg−1 lipid, based on fish meal and fish oil as main protein and lipid sources (control diet), or diets where 20%, 35% and 50% of fish meal were replaced by crystalline amino acids, using L-lysine HCl as lysine source. To access the efficiency of the crystalline lysine source, another diet was formulated with 35% fish meal replacement but using L-lysine sulphate instead of L-lysine HCl as lysine source. Overall, growth performance, feed utilization, nutrient retention, whole-body and amino acid composition did not show significant differences among groups. In conclusion, up to 50% protein-bound amino acids can be replaced by crystalline amino acids in diets for Senegalese sole juveniles without negative effects in fish performance. Additionally, it was shown that L-lysine sulphate and L-lysine-HCl may be used interchangeably by Senegalese sole juveniles, with the potential economic benefits involved.
Meagre (Argyrosomus regius) belongs to the family Sciaenidae and is a promising candidate for Med... more Meagre (Argyrosomus regius) belongs to the family Sciaenidae and is a promising candidate for Mediterranean aquaculture diversification. As a relatively recent species in aquaculture, the physiological consequences of the immune system activation in meagre are understudied. Spleen, as a primary lymphoid organ has an essential role in meagre immune and inflammatory responses. In this study, we have evaluated the in vivo effects of lipopolysaccharide (LPS) on the spleen transcriptome of meagre by RNA-seq analysis at 4 and 24 h after injection.
Bacillus spp. are well known for their probiotic properties. Hence, the long-term feeding of Baci... more Bacillus spp. are well known for their probiotic properties. Hence, the long-term feeding of Bacillus spp. strains to different fish species has been proved to confer beneficial effects regarding growth or pathogen resistance, among others. However, whether these strains could function as mucosal adjuvants, up-regulating immune responses after a single administration, has not yet been investigated in fish. Thus, in the current work, we have performed a series of experiments in rainbow trout (Oncorhynchus mykiss) aimed at establishing the potential of two Bacillus subtilis spore-forming strains, designated as ABP1 and ABP2, as oral adjuvants/immunostimulants. As an initial step, we evaluated their transcriptional effects on the rainbow trout intestinal epithelial cell line RTgutGC, and in gut tissue explants incubated ex vivo with the two strains. Their capacity to adhere to RTgutGC cells was also evaluated by flow cytometry. Although both strains had the capacity to modulate the transcription of several genes related to innate and adaptive immune responses, it was the ABP1 strain that led to stronger transcriptional effects, also exerting a higher binding capacity to intestinal epithelial cells. Consequently, we selected this strain to establish its effects on splenic B cells upon in vitro exposure as well as to determine the transcriptional effects exerted in the spleen, kidney, and gut after a single oral administration of the bacteria. Our results showed that B. subtilis ABP1 had the capacity to modulate the proliferation, IgM secreting capacity and MHC II surface expression of splenic B cells. Finally, we confirmed that this strain also induced the transcription of genes involved in inflammation, antimicrobial genes, and genes involved in T cell responses upon a single oral administration. Our results provide valuable information regarding how B. subtilis modulates the immune response of rainbow trout, pointing to the usefulness of the ABP1 strain to design novel oral vaccination strategies for aquaculture.
Abstract The effect of dietary digestible protein to digestible energy (DP/DE) ratio on the growt... more Abstract The effect of dietary digestible protein to digestible energy (DP/DE) ratio on the growth performance and metabolic responses of Nile tilapia juveniles was evaluated. Five experimental diets were formulated with increasing DP/DE ratio (13.2, 15.5, 18.4, 20.0, and 22.6 mg kJ−1) and fed to eight replicates of Nile tilapia (initial body weight of 9.3 g) for 110 days. The apparent digestibility coefficients of the diets were determined in a parallel trial. Digestibility coefficients of dry matter, crude protein, and crude energy linearly decreased with increasing dietary P/E ratios. A quadratic effect of dietary DP/DE ratio on growth performance was observed, and maximum weight gain (g kg−1 day−1) or daily growth increment was attained with a dietary DP/DE ratio of 16.5 and 17.2 (mg kJ−1), respectively. Feed intake and energy retention (kJ ABW kg−1 day−1) linearly decreased, and feed efficiency linearly increased with increased dietary DP/DE ratio. The increase of dietary DP/DE ratio decreased the whole body, muscle, hepatic, and visceral lipid content and increased the fillet yield. The decrease of dietary DP/DE linearly increased nitrogen retention (% N intake) and whole-body lipid deposition through the reduction of amino acid catabolism (GDH and ALAT) and gluconeogenesis (FBPase) related enzymes and the increase of glycolysis (GK and HK) and lipogenesis- (G6PDH and ME) related enzymes. In conclusion, a dietary DP/DE ratio of 16.5–17.2 mg kJ−1 promoted the maximum growth performance of Nile tilapia juveniles. However, further studies are required to evaluate if a fine-tuning of the protein amino acid profile would allow a further reduction of the optimum dietary DP/DE ratio. Metabolic response to the decrease in dietary DP/DE levels suggested activation of glycolysis and lipogenesis and inhibition of amino acid catabolism and gluconeogenesis, highlighting the high capacity of Nile tilapia for metabolic utilization of dietary carbohydrates.
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