Utilization of monounsaturated fatty acid (18:1n-9, oleic acid) by freshwater prawn Macrobrachium rosenbergii (de Man) juveniles

The utilization of oleic acid as an energy source and the effects of oleic acid levels and/or dietary soy bean lecithin (SBL) on oleic acid utilization, growth and survival, and lipid class and fatty acid compositions of freshwater prawn, Macrobrachium rosenbergii (de Man), juveniles were determined.
Increase in levels of dietary oleic acid from 10 to 80 g kg⁻¹ significantly ( P ≤ 0.05) reduced growth, survival and feed conversion efficiency of M. rosenbergii juveniles during the 40-day feeding period. Inclusion of 20 g kg⁻¹ SBL had no significant effect ( P ≥ 0.05) on growth and survival, nor was there any interactive effect between dietary SBL and oleic acid levels.
Body fatty acid profile of prawns reflected dietary fatty acid quantity. The fatty acid composition of prawns fed diets containing 80 g kg⁻¹ oleic acid had tremendously high proportions of oleic acid. Polar lipids, mostly phosphatidylcholine (PC), constituted the bulk of the extracted total lipids. Prawns fed with SBL had significantly ( P ≥ 0.05) higher PC content.
Oleic acid was metabolized for energy by M. rosenbergii juveniles at the same rate regardless of dietary level of SBL and/or oleic acid. Expired ¹⁴CO₂ accounted for half of the ingested radioactivity 48 h after feeding with labelled diets. No significant difference in the amount of ¹⁴CO₂ expired by prawns fed the labelled test diets was found. Per cent radioactivity ingested and absorbed into the body was also not significantly different in prawns of the different dietary treatments.     

Protein Requirements of the Freshwater Prawn Macrobrachium rosenbergii Evaluated by the Factorial Method

The dietary protein requirement of the freshwater prawn Macrobrachium rosenbergii to obtain the maximum body protein retention was assessed by the estimated protein needed daily for maintenance (M) and body protein increment (G). The body protein increment was estimated by quantifying body nitrogen increments when the prawn was fed high‐protein diets composed primarily of casein. The protein required for maintenance was estimated by regressing weight gains in feeding experiments using graded dietary levels of casein. The true daily retention (R) or increase in body protein of the prawn corresponds to the sum of M and G. The values of M, G, and R determined in the present study were 3.86, 0.24, and 4.10 g/kg body weight/d, respectively. On the basis of the daily body protein increment and the net protein utilization of casein (58%), dietary protein requirement of the juvenile M. rosenbergii for maximum body protein retention was suggested to be about 7.1 g/kg body weight/d.     

Growth,nutrient utilization,oxidative condition,and element composition of juvenile red sea bream <Emphasis Type="Italic">Pagrus major</Emphasis> fed with fermented soybean meal and scallop by-product blend as fishmeal replacement

A feeding trial was conducted to evaluate the effect of fermented soybean meal and scallop by-product blend (3:2) (FP) on the performance of juvenile red sea bream. Five isocaloric diets were prepared by replacing 0% (FP0), 15% (FP15), 30% (FP30), 45% (FP45), and 60% (FP60) fishmeal (FM) protein with FP, respectively. Triplicate groups of fish (initial mean weight 2.83 g) were fed the test diets for 45 days in a flowthrough seawater system. The results demonstrated that growth rates of fish fed FP0, FP15, and FP30 were similar, and significantly higher (P < 0.05) than those of FP45 and FP60. Nutrient utilization was significantly lower in FP60, with no differences found among the other groups. Dietary heavy-metal contents were affected by inclusion of FP, impacting on whole-body heavy-metal contents. In terms of oxidative stress, fish fed the FP30 diet were in the best condition, since this fish group showed the least oxidative-stressed condition as well as the highest tolerance against oxidation. In conclusion, the approach of utilizing this fermented mixture is promising and it could replace at least 30% FM protein in red sea bream diet without negative effects on performance, body composition or health of fish.     

Effect of high inclusion of rendered animal by‐product ingredients on growth,digestibility and economic performances in climbing perch Anabas testudineus

A 70‐day growth trail was conducted to investigate the effects of inclusion of high levels of meat and bone meal (MBM) and protein concentrate (PC) on growth, digestibility and economic performances of climbing perch, Anabas testudineus. Four isonitrogenous diets were formulated by lowering the level of dietary fishmeal protein at 0 (D₁, control), 70 (D₂), 85 (D₃) and 100% (D₄) with a mixture of MBM and PC protein (1:1). Triplicate groups of 300 fish (mean weight of 0.80 g) stocked in each 40 m² pond and fed the respective test diets. A digestibility trial was conducted after the growth trial in indoor glass aquarium. The result showed that growth parameters were significantly decreased (P < 0.05) with fishmeal replacement levels. However, significant differences were not found in feed conversion ratio and survival of fish. No difference was also found in protein efficiency ratio among D1, D2 and D3. Similar to growth parameters, total fish production was highest in D1, intermediate in D2 and D3; and lowest in D4. Apparent digestibility coefficients of dry matter, protein and lipid were highest (P < 0.05) in D1 and lowest in D4. The economic analysis revealed that the benefit cost ratio was ranked by D₃ (1.81), D₂ (1.71), D₁ (1.66) and D₄ (1.46) respectively. Upon considering the overall performances and unavailability of finite protein sources, it can be concluded that 70–85% fishmeal could be replaced with a mixture of MBM and PC (1:1) in practical diets for climbing perch.     

Physiological response,blood chemistry profile and mucus secretion of red sea bream (<Emphasis Type="Italic">Pagrus major</Emphasis>) fed diets supplemented with <Emphasis Type="Italic">Lactobacillus rhamnosus</Emphasis> under low salinity stress

Environmental stressors caused by inadequate aquaculture management strategies suppress the immune response of fish and make them more susceptible to diseases. Therefore, efforts have been made to relieve stress in fish by using various functional feed additives in the diet, including probiotics. The present work evaluates the effects of Lactobacillus rhamnosus (LR) on physiological stress response, blood chemistry and mucus secretion of red sea bream (Pagrus major) under low salinity stress. Fish were fed four diets supplemented with LR at [0 (LR0), 1 × 10² (LR1), 1 × 10⁴ (LR2) and 1 × 10⁶ (LR3) cells g^?1] for 56 days. Before stress, blood cortisol, urea nitrogen (BUN) and total bilirubin (T-BIL) showed no significant difference (P > 0.05), whereas plasma glucose and triglyceride (TG) of fish-fed LR2 and LR3 diets were significantly lower (P < 0.05) than those of the other groups. Plasma total cholesterol (T-CHO) of fish-fed LR3 diet was significantly (P < 0.05) lower than that of the other groups. Furthermore, total plasma protein, mucus myeloperoxidase activity and the amount of mucus secretion were significantly enhanced in LR-supplemented groups when compared with the control group (P < 0.05). After the application of the low salinity stress test, plasma cortisol, glucose, T-CHO and TG contents in all groups showed an increased trend significantly (P < 0.01) compared to the fish before the stress challenge. However, plasma total protein and the amount of secreted mucus showed a decreased trend in all groups. On the other hand, BUN, T-BIL and mucus myeloperoxidase activity showed no significant difference after exposure to the low salinity stress (P > 0.05). In addition, the fish that received LR-supplemented diets showed significantly higher tolerance against low salinity stress than the fish-fed LR-free diet (P < 0.05). The physiological status and the detected immune responses, including total plasma protein and mucus myeloperoxidase activity in red sea bream, will provide a more comprehensive outlook of the effects of probiotics to relieve stress in fish.     

Replacement of squid and krill meal by snail meal (Buccinum striatissimum) in practical diets for juvenile of kuruma shrimp (Marsupenaeus japonicus)

A 60‐day feeding trial was conducted to investigate the effects of substituting squid and krill meal with marine snails (Buccinum striatissimum) into the diets of juvenile kuruma shrimps (Marsupenaeus japonicus). Five experimental diets were formulated to contain varying levels of snail meal at 0%, 25%, 50%, 75% and 100% (D1, D2, D3, D4 and D5, respectively) and fed to juvenile kuruma shrimps (initial mean weight 0.27 ± 0.02 g). The results showed that weight gain, feed intake and specific growth rate were improved significantly in D4 and D5 groups when compared with D1 group (p < 0.05). Significant differences were not detected in survival rate among all shrimps fed diets containing several levels of snail meal (p > 0.05). Crude protein content of shrimps fed the control diet was significantly lower than other treatments (p < 0.05). Lipid content in shrimps fed 50% snail meal were significantly higher than the control while cholesterol content in shrimps fed 100% snail meal were significantly decreased and polyunsaturated fatty acid contents were significantly increased in shrimps fed 75%–100% snail meal (p < 0.05). These results suggest that supplementing snail meal for complete replacement of squid and krill meal can be done to improve juvenile kuruma shrimps’ growth and reducing their cholesterol levels.     

Effect of replacing fishmeal with canola meal on growth and nutrient utilization in kuruma shrimp Marsupenaeus japonicus (Bate)

A feeding trial was conducted to assess the nutritional values of canola meal as a substitute for fishmeal in diets for kuruma shrimp using five isocaloric diets (190 kJ kg^?1) prepared by replacing 0%, 10%, 20%, 30% and 40% of fishmeal protein with canola meal protein in CM0, CM10, CM20, CM30 and CM40 diets respectively. Triplicate groups of juveniles (0.19 g) were fed the respective diets for 60 days in tanks. At the end of trial, weight gain (%) and specific growth rate (% day^?1) were not significantly (P > 0.05) different among shrimp fed CM0, CM10 and CM20 diets. However, growth was significantly (P < 0.05) decreased in shrimp fed CM30 and CM40 diets. As with growth performance, feed intake, feed conversion ratio and protein efficiency ratio were also decreased (P < 0.05) in CM30 and CM40 groups. Whole body dry matter, methionine and proline were significantly decreased with canola meal substitution levels. In general, retention efficiency of protein and indispensible amino acids were decreased as canola meal increased in diets. It may be concluded that 20% fishmeal protein can be successfully replaced with canola meal, while supplementation of amino acids or blending with complementary proteins could facilitate higher fishmeal replacements in kuruma shrimp diets.     

Can fermented soybean meal and squid by‐product blend be used as fishmeal replacements for Japanese flounder (Paralichthys olivaceus)?

An experiment was carried out to evaluate fermented soybean meal and squid by‐product blend (1:1) (FP) as replacement of fishmeal (FM) for Japanese flounder, Paralichthys olivaceus. Five isocaloric (19 kJ g^?1) diets were prepared by replacing 0 (FP0), 12 (FP12), 24 (FP24), 36 (FP36) and 48% (FP48) FM protein with FP. Triplicate groups of juveniles (mean weight of 3.9 g) were delivered the test diets for 8 weeks in a flow‐through sea water system. The results showed that there were no significant differences (P > 0.05) among the growth rates of fish fed FP0, FP12, FP24 and FP36 diets. Growth and nutrient utilization parameters were significantly reduced in fish fed FP48 diet. Although, whole body proximate composition of fish were not significantly affected by the dietary treatments compared to the control; methionine and phenylalanine contents were significantly decreased in FP48 group. Protein retention was also significantly decreased in the similar group of fish. Dietary treatments did not alter most of the plasma metabolites, while some of the health parameters were improved in the replacement groups. Results suggested that FP is a potential candidate for alternative protein ingredient in aquafeed and can replace 36% FM protein in the diet of Japanese flounder.     

Effects of dietary inactivated Pediococcus pentosaceus on growth performance,feed utilization and blood characteristics of red sea bream,Pagrus major juvenile

A feeding trial was carried out to determine effects of dietary supplements of inactivated Pediococcus pentosaceus (PP) on growth, feed utilization and blood characteristics of red sea bream. Five diets containing different concentrations [0 (PP0), 1.6 × 10¹⁰ (PPI), 1.6 × 10¹¹ (PPII), 1.6 × 10¹² (PPIII) and 3.2 × 10¹² (PPIV) cells g^?1] of PP were fed to fish for 56 days. At the end of the feeding trial, the obtained results revealed a significant increase (P < 0.05) in weight gain, specific growth rate and skin mucus secretion in all PP‐supplemented groups when compared with control group. Moreover, fish fed PPIII and PPIV diets resulted in significantly higher final body weight, feed efficiency ratio and bactericidal activity than those of fish fed PP0 diet (P < 0.05). Further, fish fed the PPIII diet also had a higher feed intake, protein efficiency retention, haematocrit, mucus lysozyme activity (LA), plasma and serum proteins than those of PP0 fed group (P < 0.05). Similarly, fish fed PPIV diet resulted in a significant increase in serum LA, peroxidase activity and tolerance against low‐salinity stress test (P < 0.05). Considering these promising results, we suggest that the supplementation of PP Prep improves growth and health conditions of Pagrus major.