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We evaluated the efficacy of mozuku fucoidan supplementation to alternative dietary proteins used in fish meal (FM) replacement to enhance growth, immunity, and stress resistance of Pagrus major. Seven isonitrogenous (45% protein) experimental diets were formulated where diet 1 (D1) was FM-based control diet. Diets 2 to 7 were formulated by replacing 25, 50, and 75% of FM protein with soy protein isolate (SPI) protein, and each replacement level was supplemented without or with fucoidan at 0.4% for diet groups D2 (FM25), D3 (FM25Fu), D4 (FM50), D5 (FM50Fu), D6 (FM75), and D7(FM75Fu), respectively. Each diet was randomly allocated to triplicate groups of fish (4.1 g) for 56 days. Significantly higher weight gain and specific growth rate were observed in fish fed FM50Fu diet group, and it was not differed (P > 0.05) with fish fed FM25Fu diet group. FM-based control diet showed intermediate value, and it was not differed (P > 0.05) with or without fucoidan-supplemented ≤ 50% FM replacement groups and FM75Fu diet group. Significantly lower growth performances were observed in FM75 diet group. At each replacement level, fucoidan-supplemented groups showed nonsignificant improvement of feed utilization performances. Fish fed fucoidan-supplemented diets showed best condition of oxidative and freshwater stress resistance. Lysozyme activity, NBT, and peroxidase activity showed higher (P > 0.05) values in fucoidan-supplemented groups compared with the non-supplemented groups. Catalase activity was significantly lower in FM75Fu diet group. Catalase activity is significantly influenced by the interaction effects of fucoidan and FM replacement level. In conclusion, fucoidan supplementation could increase the efficiency of utilizing SPI (≥ 75%) without any adverse effects on red sea bream performance.

We determined the dietary inosine effects in gradually replaced fishmeal (FM) with soybean meal (SBM) protein-based diets on growth, digestibility, immunity, stress resistance and gut morphology of juvenile amberjack. Seven experimental diets were formulated to be nearly isonitrogenous (48% crude protein) where diet 1 (D1) was FM based control diet. Diet 2 to 7 were formulated by replacing 25, 50 and 75% of FM protein with SBM and each replacement level was supplemented with or without inosine at 0.6% for diet groups D2(FM25INO), D3(FM25), D4 (FM50INO), D5(FM50), D6(FM75INO) and D7(FM75), respectively. Triplicate groups of fish (24.9 g) were randomly stocked in 200 L polycarbonate tanks at a rate of 24 fish per tank and fed to satiation twice daily for 56 days. After the feeding trial, final weight, specific growth rate, and weight gain were not significantly different among the treatments with that of the 50% replacement containing inosine. Without inosine-supplemented 50% replaced group and with or without inosine-supplemented 75% replaced group showed reduced growth and feed utilization performances. The apparent digestibility coefficients of dry matter, protein and lipid were significantly higher in control and other replacement groups with inosine supplementation. In the case of oxidative stress parameters, fish fed inosine-supplemented diets showed the best condition. Stress resistance against low salinity exposure (LT50), significantly increased with inosine supplementation and was highest in inosine-supplemented 50% replacement diet group. Total serum protein (TSP), alternative complement pathways (ACH50), lysozyme activity (LA), bactericidal activity (BA) and peroxidase activity (PA) tended to be higher in inosine-supplemented groups compared to the non-supplemented groups. Simultaneously, enterocyte height, fold height, and microvillus height of the anterior and posterior enteric sections increased significantly with the inosine supplementation. Results of the study indicated that at least half of the fishmeal could be replaced with soybean meal and supplementation of inosine in the diets of juvenile amberjack. Moreover, inosine administration in 50 to 75% FM replacement groups could be helpful to improve the digestibility, immune responses, stress resistance, and intestinal health condition of fish.

In the present study we investigate the dietary administration effects of uridine monophosphate (UMP) to enhance the growth, hematological profile, innate and adaptive immune functions and stress resistance of juvenile red sea bream, Pagrus major . A casein fishmeal based semi-purified basal diet supplemented with 0% (control), 0.1% (UMP-0.1), 0.2% (UMP-0.2), 0.4% (UMP-0.4) and 0.8% (UMP-0.8) purified UMP to formulate five experimental diets. Each diet was randomly allocated to triplicate groups of fish (mean initial weight 2.9 g) for 56 days. In general dietary UMP supplementation tended to improve growth performances (final body weight, % weight gain and specific growth rate), in which significantly higher performances were found in diet group UMP-0.4 followed by diet groups UMP-0.8, UMP-0.1 and UMP-0.2. UMP supplementation resulted increased feed conversion efficiency and protein efficiency ratio and significantly higher value (P 0.05) with dietary UMP supplementation. Fish in control group without UMP supplementation showed significantly lower growth and feed utilization performances. The capabilities of enhancing immune responses of fish fed UMP supplemented diets were detected by nonspecific and acquired immune parameters measured in this study. Peroxidase activity (PA) was significantly higher in fish fed diet group UMP-0.8 and higher (P Vibrio anguillarum . In the 15th day after vaccination, significantly higher agglutination antibody titer was found in diet group UMP-0.4 and simultaneously other supplemented diet groups showed intermediate values. In terms of oxidative stress, diet group UMP-0.4 showed best condition with low oxidative stress and high antioxidant levels. Moreover, the fish fed UMP supplemented diets had better improvement (P

A 50-day feeding trial was conducted to determine the effects of dietary inosine on growth performance, immune responses, oxidative stress and gut morphology of juvenile amberjack, Seriola dumerili. Five isonitrogenous (52% crude protein) and isolipidic (14% crude lipid) semi-purified test diets were prepared by supplementing incremental levels of dietary inosine nucleoside at 0% (D1, control), 0.1% (D2), 0.3% (D3), 0.6% (D4) and 0.9% (D5), respectively. Triplicate groups of juvenile with an initial average weight of approximately 26 g were randomly stocked in fifteen, 200L polycarbonate tanks at a stocking density of 20 fish per tank. The fish were hand-fed twice daily to apparent satiation level. At the end of the feeding trial, final body weight (g), weight gain (%) and specific growth rate (% day− 1) were significantly (P

A feeding trial was conducted to determine the efficacy of nucleotide related products on growth, blood chemistry, oxidative stress and growth factor gene expression of juvenile red sea bream. Five experimental diets were formulated to contain 49% protein, 11% lipid and the diet without nucleotide related product supplementation was the control (D1). Nucleotide related products like; nucleoside by-products (NBPs) and inosine were supplemented at 1, 3 and 0.03, 0.1% consecutively with basal ingredients of D1 and named as D2, D3 & D4 and D5 respectively. Experimental diets were fed to triplicate groups of fish for 60 days. Fish fed diet D5 showed significantly the highest final body weight and % weight gain followed by the diet groups D2 and D4. Fish fed control group showed the lowest growth performance and were not differed significantly with diet group D3. Feed conversion ratio and protein efficiency ratio were also significantly higher in diet group D5, whereas the other supplemented group showed intermediate value. A wide variation in some of the blood parameters was observed. In case of oxidative stress parameters, fish fed inosine supplemented diets showed the best conditions because they performed better under oxidative stress conditions as well as had the highest tolerance against oxidation. Among NBP supplemented groups, diet group D2 also showed acceptable conditions of oxidative stress tolerance. Stress resistance against low salinity exposure (LT50) also increased with dietary supplementation and it was significantly the highest in fish fed diet group D5. Total serum protein, serum lysozyme activity and total peroxidase content tended to be higher (P > 0.05) in NBP and inosine supplemented diet groups. In numerically higher hepatic IGF-1, mRNA expression was found in diet groups D2 and D4. However, IGF-1 and IGF-2 mRNA expressions were not significantly altered by dietary supplementations in the present study. Considering overall performance of the present study, we concluded that inosine and low concentration of NBP (1%) could be effectively used as dietary supplements for better growth and health performance of Pagrus major. Statement of relevance In this study industrial by-products, nucleoside by-products and relatively low cost nucleoside, inosine has been evaluated as potential functional nutrients for marine fish such as red sea bream. Utilization of these functional supplements will help to reduce nucleotide administration cost in fish feed as well as to develop low fishmeal based functional aquafeed in the near future.

Inosine and inosine monophosphate (IMP) are the most extensively studied specific nucleotide for feeding stimulation research rather than using as functional nutrients for potential growth and health benefit of aquatic species. Therefore, a 10-week feeding trial was conducted to determine comparative effects of inosine and IMP as functional nutrients on growth performance, immune responses, stress resistance and intestinal morphology of juvenile red sea bream (Pagrus major). Casein based semi-purified basal diet was formulated to contain 54% protein, 11% lipid, without inosine and IMP supplementation (Control). Four levels of inosine nucleoside (0.2, 0.4, 0.6 and 0.8% for diet groups INO-0.2, INO-0.4, INO-0.6 and INO-0.8 respectively) and IMP nucleotide (0.2, 0.4, 0.6 and 0.8% for diet groups IMP-0.2, IMP-0.4, IMP-0.6 and IMP-0.8 respectively) were added to the basal diet. Each diet was randomly allocated to triplicate groups of fish with initial average weight of 6.6 g. The results indicated that dietary inosine and IMP supplementations tended to improve growth performances, in which one of the best ones was found in diet group IMP-0.6, but the values did not significantly differ from those in diet groups IMP-0.4 and INO-0.4, respectively. Superoxide dismutase, peroxidase and bactericidal activity were significantly influenced by dietary supplementation of inosine and IMP. However, the values of these parameters were not significantly different among diet groups INO-0.4, IMP-0.4 and IMP-0.6. Total serum protein, catalase and lysozyme activity were also improved (P > 0.05) by dietary supplementation of inosine and IMP. Supplementations improved both freshwater stress and oxidative stress resistances. Fish fed diet groups INO-0.4 and IMP-0.6 showed the least oxidative stress condition. Inosine and IMP supplementations significantly increased enterocyte height (hE), fold height (hF) of both anterior and posterior intestine and microvillus height (hMV) of posterior intestine compared to those of the control. The highest hF observed in diet group IMP-0.4 and the mean value was not significantly different from those in other IMP diets, INO-0.4 and INO-0.6, respectively. Significantly highest anterior hE and posterior hF, hE and hMV observed in diet group INO-0.4. However, no significant difference of posterior hF observed between INO-0.4 and IMP supplemented diet groups. Fish fed supplemented diets also showed improved survival compared to control (P > 0.05). Considering overall performances, it can be concluded that diet groups INO-0.4 and IMP-0.4 showed relatively better performance among inosine and IMP supplemented diet groups respectively compared to control. Furthermore, diets supplemented with either inosine or IMP at 0.4% are beneficial to promote growth, immune responses, stress resistance and intestinal health condition of juvenile red sea bream. Statement of relevance In this study inosine and inosine monophosphate has been evaluated as potential functional nutrients for marine fish such as red sea bream. Since supplementations of such immunostimulant-like functional nutrients are very important for the development of functional aquafeeds, I hope findings of this paper will help to develop low fishmeal based functional aquafeeds in near future.

A 56- day feeding trial was carried out to determine effects of purified nucleotide mixture for red sea bream ( Pagrus major ). Five dietary level of purified nucleotide mixture containing equal portion of inosine 5′ monophosphate (IMP), adenosine 5′ monophosphate (AMP), guanosine 5′ monophosphate (GMP), uridine 5′ monophosphate (UMP) and cytidine 5′ monophosphate (CMP) were supplemented to the basal diet (control, D1) at 0.5 (D2), 1.0 (D3), 1.5 (D4), 2.0 (D5) and 2.5 (D6) g kg − 1 . Triplicate groups of fish (initial weight: 2.6 g) were stocked in 100-L polycarbonate circular tanks at a density of 18 fish per tank under the flow-through system, and were fed the respective test diets twice daily to satiation level. After feeding trial, significantly higher growth performances, survival (%) and feed utilization were observed in fish fed with 1.5% mixed nucleotide supplemented diet (D4). Growth performance parameters were not differed significantly among diet groups D3 and D4. Feed conversion ratio, protein efficiency ratio and survival were not differed among diets D2 to D5. All the growth and feed utilization parameters were significantly lower in D1 and D6. In case of oxidative stress parameters fish fed nucleotide supplemented diets showed best condition because of the least oxidative stressed condition as well as the highest tolerance against oxidation. Stress resistance against low salinity exposure (LT 50 ), significantly increased with nucleotide supplementation and was highest in D4. Total serum protein, serum lysozyme activity and total peroxidase content tended to be higher (P > 0.05) in nucleotide supplemented group. Catalase activity reduced (P − 1 mixed nucleotides to promote growth, immune responses and stress resistance of juvenile red sea bream.