Effects of supplemental coated or crystalline methionine in low-fishmeal diet on the growth performance and body composition of juvenile cobia Rachycentron canadum （Linnaeus）

We evaluated the effects of supplemental coated and crystalline methionine （Met） on the growth performance and feed utilization of juvenile cobia （Rachycentron canadum Linnaeus） in a 60-d feeding trial. Fish groups were fed one of six isonitrogenous and isolipidic diets： 1） fishmeal control; 2） un- supplemented experimental （low-fish-meal diet deficient in Met）; or 3） one of four Met diets supplemented with crystalline L-Met, cellulose-acetate-phthalate coated L-Met, acrylic-resin coated L-Met, or tripalmitin- polyvinyl alcohol coated L-Met. The test diets were fed to triplicate groups of cobia （initial body weight 5.40-4-0.07 g） twice a day. The weight gain and specific growth rate of the fish fed the RES diet were highest among the Met-supplemented groups and were 23.64% and 7.99%, respectively, higher than those of the fish fed with the un-supplemented experimental diet （P〈0.05）. The protein efficiency ratio of the fish fed the MET diet was significantly higher than that of the fish fed the un-supplemented experimental diet and the fish in the other methionine supplementation groups （P〈0.05）. Our results suggest that supplementation of crystalline Met in low-fish-meal diets promotes the growth performance of juvenile cobia.     

Feasibility of partial replacement of fishmeal with proteins from different sources in diets of Korean rockfish (Sebastes schlegeli)

An 8-week feeding experiment was conducted in an indoor recirculation seawater system to investigate the effects of partial replacement of dietary fishmeal with proteins from five sources on the growth performance and feed utilization of Sebastes schlegeli. Six isonitrogenous and isoenergetic diets were formulated using fishmeal (FM, the control) as sole protein source, or proteins from five sources including poultry by-product meal (PBM), meat and bone meal (MBM), soybean meal (SBM), cottonseed meal (CSM) and canola meal (CNM). Fifteen percent of the crude protein provided by fish meal was replaced, respectively. The results showed that the differences in specific growth rate (SGR) and survival rate (SR) among fish fed PBM, MBM, SBM, CSM and whole FM diets were not significant. However, SGR and SR of fish fed CNM diet was significantly lower than that of other treatments. Feeding rate, feed conversion, nutrient retention showed similar patterns to that of growth. Fish fed CSM and CNM showed significantly lower apparent digestibility coefficient (ADC) of dry matter and gross energy than those fed others while fish fed CNM showed lower ADC of crude protein than those fed others (P<0.05). These results suggested that it was feasible to substitute 15% dietary protein provided by fishmeal with PBM, MBM, SBM and CSM, respectively, but not with CNM as the replacement with CNM reduced fish growth and feed utilization.     

Effect of dietary phosphorus on the growth and body components of juvenile Synechogobius hasta

The effect of dietary phosphorus on the growth and body components of juvenile Synechogobius hasta was determined. Different percentages of dietary phosphorus (0.63, 0.77, 0.93, 1.06, 1.22 and 1.36) were tested by feeding the fish (body weight, 15.81 g ± 0.32 g; 20 individuals each group; 3 groups each percentage) at a surplus of 5%–10% above satiation for 35 d. Dietary phosphorus did not significantly affect the specific growth rate, feed intake, feed conversion ratio and protein efficiency rate. Nitrogen retention was found to be the highest in fish fed the diet containing 1.06% of phosphorus; however, this was not significantly different from other diets. Fish fed the diet containing 0.93% of phosphorus showed the highest phosphorus retention; similar phosphorus retention rates were found in fish fed the diets containing 0.77% and 1.06% of phosphorus. Fish fed the diet containing the highest percentage of dietary phosphorus were found to contain the least whole body lipid, lower than fish fed other diets (P<0.05). The protein content increased from 18.59% to 19.55% (although not significant) with the decrease of body lipid content (P>0.05). The contents of the whole body ash, whole body phosphorus and vertebrae phosphorus increased with dietary phosphorus percentage up to 1.06 (P<0.05), reaching a plateau after that. Dietary phosphorus did not significantly influence the muscle components (protein, lipid and moisture). Condition factor and hepatosomatic index were the highest in fish fed the diet containing 0.63% of dietary phosphorus; however, this was not significantly different from those of other diets. The second-order polynomial regression of phosphorus retention against dietary phosphorus identified a breakpoint at 0.88% of dietary phosphorus. However, the dietary requirement of phosphorus for maintaining maximum phosphorus storage determined by broken-line analysis of the contents of whole body phosphorus, and ash and vertebrae phosphorus was 1.06% of the diet.     

Effects of Dietary Protein Level on Growth and Utilization of Protein and Energy by Juvenile Mangrove Red Snapper （ Lutjanus argentimaculatus ）

A feeding trial was conducted in a recirculating water system to investigate the effects of dietary protein levels on growth, feed utilization, hepatosomatic index and liver lipid deposition of juvenile red snapper, Lutjanus argentimaculatus (average initial wet weight 8.0 ± 0.39 g and total length 3.14 ± 0.3 cm). In the experiment, six fishmeal-based diets were formulated to contain various protein levels (20% to 45% in 5% increments), with dietary energy ranging from 2210.7kJ lOOg to 2250.2kJlOOg dry matter. The protein to energy ratios of diets ranged from 8.58 mg protein kJ⁻¹ to 20.03 mg protein kJ⁻¹. Diets were fed for 90d to triplicate groups of fish stocked in 0.128m³ seawater tanks, 25 individuals each. The daily ration of 2% wet body weight was offered to the fish thrice a day. The fish at the end of the study had more than ten-fold (77.0g) increase in weight compared to the initial (8.0g). Fish fed diets of 40% and 45% protein produced significantly (P<0.05) higher weight gain of 77.2g and 76.5g, and specific growth rate (SGR) of 2.65% and 2.62% than those of 67.0 g and 68.3g, and 2.49% and 2.51% of the other diets. The broken-line regression of SGR against dietary protein level yielded an optimum dietary protein requirement of 42.6% (Y=−1.6295 + 0.1114 X ²,P<0.05). Survival remained 100% among groups. Feed conversion ratio decreased from 0.45 for fish fed 20% dietary protein to 0.35 for fish fed 45% dietary protein. Nitrogen intake increased with an increase in dietary protein, which in turn resulted in an increase in nitrogen gain of fish whole body. Fish fed 40% and 45% protein diets showed higher (P<0.05) nitrogen gain (0.27g and 0.26g) than those (0.23g and 025g) fed all other diets. Gross energy intake (GEI) in fish fed 45% protein was lower (600.67kJ) than that (607.97 kJ) of 40% protein diet, though the differences were not statistically significant (P>0.05); GEI ranging from 677.31 kJ to 663.20 kJ at remaining four diets (20% to 35% protein) did not appear to differ significantly (P>0.05). The highest energy gain of 518.33 kJ was obtained with fish fed 40% protein, resulting in the highest energy retention efficiency of 85.26%. The hepatosomatic index of fish fed diets of 20%, 25%, 30% and 35% protein were significantly (P<0.05) higher (2.09% to 2.57%) than those (1.44% and 1.41%) of fish fed diets containing 40% and 45% protein. Liver lipid contents decreased from 8.72% to 7.0% in fish fed dietary protein of 20% to 45% in 5% increments. Results suggest that the diet containing 40% to 42.6% protein with a P/E ratio of 17.6 mg protein kJ⁻¹ is required for good growth of L. argentimaculatus weighing between 8.0 g and 85.2 g under the culture conditions of the present study.     

Effects of brown fish meal replacement with fermented soybean meal on growth performance, feed efficiency and enzyme activities of Chinese soft-shelled turtle, Pelodiscus sinensis

A 120-day feeding experiment was conducted to investigate the effects of partial replacement of brown fish meal (BFM) by fermented soybean meal (FSBM) in diets of Chinese soft-shelled turtle (Pelodiscus sinensis). The turtles (initial mean body weight, (115.52 ± 1.05) g) were fed with three experimental diets, in which 0%, 4.72% and 9.44% BFM protein was replaced by 0%, 3% and 6% FSBM, respectively. Results showed that the feeding rate (FR), specific growth rate (SGR) and feed efficiency ratio (FER) of turtles fed with the diet containing 3% FSBM were not significantly different from the control group (0% FSBM) (P > 0.05). However, FR, SGR and FER of turtles fed with the diet containing 6% FSBM were significantly lower than those of the control group (P < 0.05). No significant differences were observed in the activities of serum glutamic-oxalacetic transaminase and glutamicpyruvic transaminase among dietary treatments (P > 0.05). However, the uric acid concentration in turtles fed with the diet containing 3% or 6% FSBM was significantly lower than that in the control group (P < 0.05). There were no significant differences in the activities of lysozyme, alkaline phosphatase and total superoxide dismutase among dietary treatments (P > 0.05). The results suggested that FSBM could replace 4.72% BFM protein in turtle diets without exerting adverse effects on turtle growth, feed utilization and measured immune parameters.     

Effect of dietary cottonseed meal on growth performance,physiological response,and gossypol accumulation in pre-adult grass carp, <Emphasis Type="Italic">Ctenopharyngodon idellus</Emphasis>

Cottonseed meal (CM) was used at up to 36.95% content in the diet (replacing 60% of dietary fish meal protein) without any negative eff ects on growth performance of pre-adult grass carp (initial body weight, 761 g) under outdoor conditions. A culture trial was conducted in net cages installed in a large concrete pond. Seven isonitrogenous and isoenergetic diets containing a gradient of CM concentrations (0, 12.2%, 24.4%, 36.6%, 48.8%, 54.8%, and 61.0%) as replacement for dietary fish meal protein (0, 20%, 40%, 60%, 80%, 90%, and 100%) were formulated. Dietary non-resistant starch (from maize) was inverse to dietary CM. Growth performance and feed utilization of fish fed the diets containing CM replacing 0–40% fishmeal protein were not aff ected after the 6-week feeding trial. Accumulation of hepatopancreatic total gossypol in the hepatopancreas was significantly correlated with free gossypol content in the diets (HTG=88.6+1.5×DFG, R ²=0.89, P<0.05). Intestinal α-amylase and γ-glutamyl transpeptidase activities rose along with increasing dietary CM level. The structure of the mid-intestinal tissues and the ultrastructure of the enterocyte microvilli were normal when dietary CM was <36.6% (60% protein replacement). Increasing dietary CM content increased serum alanine aminotransferase levels but decreased serum alkaline phosphatase, cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglycerides, and albumin (P<0.05).     

Effects of dietary soy isoflavones on feed intake, growth performance and digestibility in juvenile Japanese flounder (Paralichthys olivaceus)

An 8-week feeding trial was conducted to investigate the effects of dietary soy isoflavones on feeding intake,growth performance,and digestion of juvenile Japanese flounder(Paralichthys olivaceus).Four isonitrogenous(49% crude protein) and isoenergetic(20.1 MJ kg-1) diets were formulated to contain four graded levels of soy isoflavones,namely,0,1,4 and 8 g soy isoflavones in 1 kg of diet.Each diet was randomly fed to triplicate tanks of fish(Initial average weight:2.58 g ± 0.01 g),and each tank was stocked with 35 fish.No significant difference was observed among diets with levels of 0,1 and 4 g kg-1 soy isoflavones in feed intake,weight gain,feed efficiency ratio(FER),proximate composition of fish whole body and apparent digestibility coefficients(ADC) of nutrients and energy(P>0.05).However,high dietary soy isoflavones level(8 g kg-1) significantly depressed weight gain,FER,whole-body crude lipid content of fish and ADC of nutrients(P<0.05).These results indicate that high level of dietary soy isoflavones(above 4 g kg-1) significantly depresses growth responses and FER of Japanese flounder.However,as the content of soy isoflavones in soybean meal is around 1 to 3 g kg-1,the adverse effects might be neglected when soybean products are used as a fish feed ingredient.     

Effects of dietary carbohydrate-to-lipid ratio on the growth performance and feed utilization of juvenile turbot (<Emphasis Type="Italic">Scophthalmus maximus</Emphasis>)

A 9-week feeding trial was conducted to investigate the effects of dietary carbohydrate to lipid ratio(CHO:LIP) on the growth performance and feed utilization of juvenile turbot Scophthalmus maximus(initial body weight 8.75 g ± 0.04 g). Four isonitrogenous and isoenergetic low protein level(39%) diets were formulated with increasing ratios of dietary carbohydrate to lipid(2:18, 6:18, 18:12 and 28:6). A high protein level(50%) diet with the 2:12 ratio of carbohydrate to lipid was used as the control. Results showed that the survival rate, contents of moisture, crude protein and ash in muscle were not significantly affected by dietary treatments. With the dietary CHO:LIP ratio increased from 2:18 to 18:12, weight gain rate significantly increased(P < 0.05). Higher dietary CHO:LIP ratio(28:6) resulted in the significantly decreased weight gain rate(P < 0.05). Meanwhile, this treatment also resulted in the highest daily feed intake and liver glycogen content, as well as the lowest feed efficiency(P < 0.05). Muscle glycogen content in fish fed the diet with 2:12 or 2:18 CHO:LIP ratio was significantly lower than those fed with the other three diets(P < 0.05). The present results confirmed that the juvenile turbot can utilize carbohydrate. Furthermore, the appropriate ratio of dietary carbohydrate to lipid was important to the growth and feed utilization of turbot. The proper CHO:LIP ratio based on the growth performance in the present study was determined to be 18:12 when the dietary protein level was 39%.     

Effect of Dietary Phosphorus on the Growth and Body Components of Juvenile Synechogobius hasta

The effect of dietary phosphorus on the growth and body components of juvenile Synechogobius hasta was determined. Different percentages of dietary phosphorus (0.63, 0.77, 0.93, 1.06, 1.22 and 1.36) were tested by feeding the fish (body weight, 15.81 g ± 0.32 g; 20 individuals each group; 3 groups each percentage) at a surplus of 5%–10% above satiation for 35 d. Dietary phosphorus did not significantly affect the specific growth rate, feed intake, feed conversion ratio and protein efficiency rate. Nitrogen ...     

Effects of small peptides,probiotics, prebiotics,and synbiotics on growth performance,digestive enzymes,and oxidative stress in orange-spotted grouper, <Emphasis Type="Italic">Epinephelus coioides</Emphasis>, juveniles reared in artificial seawater

Aquaculture production efficiency may increase by using feed additives. This study investigated the effects of different dietary additives [w/w: 2% small peptides, 0.01% probiotics (Bacillus licheniformis) and 0.2% prebiotics (inulin)] on growth performance, digestive enzyme activities, and oxidative stress in juvenile Epinephelus coioides reared in artificial seawater of two salt concentrations (13.5 vs. 28.5). Weight gain rate was significantly higher in fish fed the diet supplemented with small peptides, B. licheniformis, inulin, or synbiotics than that in fish fed the basal diet; the greatest weight gain rate was found in fish fed the small peptide treatment [56.0% higher than basal diet]. Higher feed efficiency was detected in fish fed the diet supplemented with small peptides than that of fish in the other dietary treatments. Total protease activity in the stomach and intestines was highest in fish fed the small peptide-treated diet, whereas lipase activity was highest in those fed synbiotics (combination of Bacillus licheniformis and inulin) than that in fish fed the other treatments. Antioxidant enzyme (total superoxide dismutase and catalase) activities and hepatic malondialdehyde content were higher in fish receiving the dietary supplements and maintained in artificial seawater containing 13.5 salinity compared with those in the control (28.5). Hepatic catalase activity in grouper fed the diets with small peptides or synbiotics decreased significantly compared with that in control fish. Overall, the three types of additives improved growth rate of juvenile grouper and digestive enzymes activities to varying degrees but did not effectively improve antioxidant capacity under low-salinity stress conditions.     

Effect of dietary olaquindox on the growth of large yellow croaker (Pseudosciaena crocea R.) and the distribution of its residues in fish tissues

Olaquindox(OLA), one of quinoxaline-N, N-dioxides, has been put under ban. However it was used as a medicinal feed additive early; it promotes the growth of livestock and prevents them from dysentery and bacterial enteritis. In this study, we evaluated the effect of dietary OLA on the growth of large yellow croaker(Pseudosciaena crocea R.) and the histological distribution of OLA and its metabolite 3-methyl-quinoxaline-2-carboxylic acid(MQCA) in fish tissues. Four diets containing 0(control), 42.5, 89.5 and 277.2 mg kg-1 OLA, respectively, were formulated and tested, 3 cages(1.0 m × 1.0 m × 1.5 m) each diet and 100 juveniles(9.75 ± 0.35 g) each cage. The fish were fed to satiation twice a day at 05:00 am and 17:00 pm for 8 weeks. The survival rate of fish fed the diet containing 42.5 and 89.5 mg kg-1 OLA was significantly higher than that of fish fed the diet containing 0 and 277.2 mg kg-1 OLA(P 0.05), while the weight gain rate of fish fed the diet containing 42.5 and 89.5 mg kg-1 OLA was significantly higher than that of fish fed the diet without OLA(control)(P0.05), but similar to that of fish fed the diet with 277.2 mg kg-1 OLA. Fish fed the diet with 277.2 mg kg-1 OLA had the highest content of OLA and MQCA in liver(3.44 and 0.39 mg kg-1, respectively), skin(0.46 and 0.09 mg kg-1, respectively) and muscle(0.24 and 0.06 mg kg-1, respectively). In average, fish fed the diet containing OLA had the highest content of OLA and MQCA in liver which was followed by skin and muscle(P 0.05), whereas OLA and MQCA were not detectable in control. Our findings demonstrated that OLA and MQCA accumulated in large yellow croaker when it was fed with the diet containing OLA, thus imposing a potential safety risk to human health.     

Effect of bioactive peptides (BPs) on the development of Pacific white shrimp (<Emphasis Type="Italic">Litopenaeus vannamei</Emphasis> Boone, 1931)

The present study was conducted to evaluate the feasibility of replacing fish meal (FM) with bioactive peptides (BPs) in diet of white shrimp (Litopenaeus vannamei). The changes in growth performance, body composition, non-specific immunity, and water quality were examined after the shrimp were fed four diets, in which 0% (control), 33.3%, 66.7% and 100% of FM was replaced by BPs, respectively. The groups were designated as Con, 1/3BPs, 2/3BPs, and 3/3BPs. A total of 720 shrimp with an initial body weight of 1.46 ± 0.78 g were fed the experimental diets for 56 days. The results revealed that: 1) the weight gain rate (WGR) in 1/3BPs, 2/3BPs, and 3/3BPs was significantly higher than that in Con (P < 0.05), while no significant difference was found on survival rate and feed conversion ratio (FCR); 2) the whole-body crude protein (CP) and crude lipids (CL) were significantly different among groups, while there was no significant difference between crude ash and phosphorus contents; 3) the levels of acid phosphatase (ACP), lysozyme (LZM), superoxide dismutase (SOD), phenol oxidase (PO) and bactericidal activity increased significantly with the inclusion of BPs; 4) in terms of water quality, no significant difference was found in pH and dissolved oxygen among diets during the whole experimental period. Moreover, even though nitrite and ammonium levels tended to increase with time, there was no significant difference among groups. The results indicated that BPs is an applicable alternative of protein source, which can substitute FM in the diets of L. vannamei; it is able to effectively promote growth performance and improve immunity. Moreover, BPs in the diets had no negative impact on water quality.     

饲料中豆粕含量对军曹鱼幼鱼碳、氮稳定同位素分馏的影响

配制全鱼粉饲料（以鱼粉为蛋白源）、10%豆柏饲料（用豆柏蛋白10%鱼粉）、20%豆柏饲料（用豆柏蛋白20%鱼粉）等3种等氮等能饲料,分别投喂体质量21.34± 1.54g的幼鱼24 d,研究饲料中豆柏蛋白含量对 军曹鱼幼鱼碳、氮稳定同位素分馈的影响。结果表明,随着养殖时间的延长,各饲料组军曹鱼δ13C逐渐上升,δ15N逐渐下降,虽然δ13C和δ15N变化速度上有差异,但除20%豆柏饲料组肌肉的δ15N外,其他各饲料组肌肉和 全鱼在实验结束时均已与饲料达到同位素平衡;军曹鱼肌肉和全鱼的△13^C和△15^N值均随饲料中豆柏蛋白含量 的增加而加大,△13C从4.19‰增加到5.04‰, △15N从0.18‰。增加到 2.20‰,军警鱼金鱼和肌肉的△13C和△15N 相似,但在同位素值变化速度上有差异,因此,在进行生态学营养级研究（长时间尺度）时,肌肉可以代表军警鱼的同位素特征,而在进行生理学研究（短时间尺度）时,肌肉的同位素变化则不能代表军警鱼的同位素变化。     

Floc meal as potential substitute for soybean meal in tilapia diets under biofloc system conditions

This study was conducted to evaluate the effect of replacing soybean meal (SBM) by low protein floc meal (LPFM; 24% CP) in tilapia diets on growth performance, feed utilization and fish chemical composition. Three isonitrogenous and isocaloric diets were formulated; control diet (C; without LPFM), FM ₂₅ (25% of SBM protein was substituted by LPFM) and FM ₅₀ (50% of SBM protein was substituted by LPFM). Nine 55l circular plastic tanks were stocked by 12 fish to form three experimental groups. No differences in tilapia performance were observed between the control and the FM ₂₅ diet. Chemical composition of fish did not differ significantly among treatments except for protein and selenium contents where the highest values were recorded in the control treatment. The highest mineral content was recorded in floc collected from the control tanks, while calcium content showed its highest value in floc collected from FM ₅₀ effluent. These data indicate that replacing soybean meal with LPFM up to 25%, had no negative effect on growth performance and potentially may improve the system sustainability. Meanwhile, the adverse effect of more inclusion of LPFM in tilapia diet may be attributed to the higher content of ash. In other word, minerals seem to cause more energy utilization in fish fed floc meal since it is needed to maintain osmotic homeostasis.

     

Growth and feed efficiency of juvenile shrimp Litopenaeus vannamei fed formulated diets containing different levels of poultry by-product meal

This feeding trial was conducted to evaluate the potential of poultry by-product meal (PBM) as a protein source in the culture ofLitopenaeus vannamei. Seven isonitrogenous and isoenergetic diets were formulated to near to commercial diet with about 40% protein and 7.5% lipid. Fish meal was replaced by 0, 30%, 40%, 50%, 60%, 70% and 100% of PBM (diets 1-7). The diet with 100% fish meal was used as a control (diet 1). Post-larvae were reared in an indoor semi-closed re-circulating system. Each dietary treatment was tested in 4 replicate tanks (260 L) of 40 shrimp, arranged in a completely randomized design. The shrimps were hand-fed for three times a day to near-satiation (0700, 1200 and 1800) for 60d. Percentage weight gain, survival, feed conversion ratio (FCR), protein efficiency ratio (PER) and body composition of shrimps were measured. There were no significant differences (P>0.05) in growth performance among shrimps fed diets 1-5 (0-60% fish meal replacement). However, shrimps fed diet 7 (100% fish meal replacement) had significantly lower (P<0.05) growth than those fed diets 1-5 (0-60% fish meal replacement). Shrimp fed diets 2-4 (30%-50% fish meal replacement) showed significantly higher growth than those fed diets 6 and 7 (70% and 100% fish meal replacement, respectively). Survival ranged from 94.7% to 100.0% and did not differ significantly (P>0.05) among different experimental diets. No differences in body composition were found among shrimps fed different diets. These results showed that up to 70% of fish meal protein can be replaced by PBM without adversely affecting the growth, survival, FCR, PER and body composition of Litopenaeus vannamei.     

Effects of Dietary Protein Level on Growth and Utilization of Protein and Energy by Juvenile Mangrove Red Snapper (Lutjanus argentimaculatus )

1Introduction The mangrove red snapper,Lutjanus argentimacu-latus(Forsskal,1775)is a carnivorous,warm-watereuryhaline fish that is considerably cultured in South-east Asia,Southern China and the Middle East(Le-ung et al.,1999;Estudillo et at.,2000;Ng et al.,2000;Catacutan et al.,2001).In Pakistan,it isknown for its good quality meat and also for its highconsumption rate.Although it fetches a premiumprice at local markets(Anonymous,2002),the in-creasing demand has generated interest towar…     

Effects of Hanseniaspora opuntiae C21 on the growth and digestive enzyme activity of juvenile sea cucumber Apostichopus japonicas

The effects of a diet containing Hanseniaspora opuntiae C21 on growth and digestive enzyme activity were estimated in juvenile Apostichopus japonicus. Groups of sea cucumbers were fed diets containing H. opuntiae C21 at 0(control), 10 4, 10 5, and 10 6 CFU(colony-forming units)/g feed. Results showed that after 45 d the specific growth rate(SGR) of sea cucumbers fed a C21-supplemented diet at 10 4 CFU/g feed was significantly higher than that of the control( P 0.05). Intestinal trypsin and lipase activities were significantly enhanced by C21 administration at 10 4 and 10 5 CFU/g feed compared with the control( P 0.05). After feeding for 23–42 d, C21 was demonstrated by denaturing gradient gel electrophoresis to be present in the intestine of sea cucumbers. In addition, after feeding the C21-supplemented diets for 15 d, the sea cucumbers were switched to an unsupplemented diet and C21 was confirmed to be capable of colonizing the intestine for at least 31 d after cessation of feeding. In conclusion, C21 was shown to successfully colonize the intestine of juvenile A. japonicus via dietary supplementation, and improve growth and digestive enzyme activity.     

Effects of small peptides,probiotics, prebiotics,and synbiotics on growth performance,digestive enzymes,and oxidative stress in orange-spotted grouper,Epinephelus coioides,juveniles reared in artificial seawater

Aquaculture production efficiency may increase by using feed additives. This study investigated the effects of different dietary additives [w/w: 2% small peptides, 0.01% probiotics( Bacillus licheniformis) and 0.2% prebiotics(inulin)] on growth performance, digestive enzyme activities, and oxidative stress in juvenile Epinephelus coioides reared in artificial seawater of two salt concentrations(13.5 vs. 28.5). Weight gain rate was significantly higher in fish fed the diet supplemented with small peptides, B. licheniformis, inulin, or synbiotics than that in fish fed the basal diet; the greatest weight gain rate was found in fish fed the small peptide treatment [56.0% higher than basal diet]. Higher feed efficiency was detected in fish fed the diet supplemented with small peptides than that of fish in the other dietary treatments. Total protease activity in the stomach and intestines was highest in fish fed the small peptide-treated diet, whereas lipase activity was highest in those fed synbiotics(combination of Bacillus licheniformis and inulin) than that in fish fed the other treatments. Antioxidant enzyme(total superoxide dismutase and catalase) activities and hepatic malondialdehyde content were higher in fish receiving the dietary supplements and maintained in artificial seawater containing 13.5 salinity compared with those in the control(28.5). Hepatic catalase activity in grouper fed the diets with small peptides or synbiotics decreased significantly compared with that in control fish. Overall, the three types of additives improved growth rate of juvenile grouper and digestive enzymes activities to varying degrees but did not effectively improve antioxidant capacity under low-salinity stress conditions.     

Growth and antioxidant status of oriental river prawn <Emphasis Type="Italic">Macrobrachium nipponense</Emphasis> fed with diets containing vitamin E

A feeding trial was carried out to investigate the dietary vitamin E requirement of the oriental river prawn Macrobrachium nipponense (weight of 0.3–0.4 g) and its effect role on antioxidant activity. Prawns were fed with seven levels of vitamin E (0, 25, 50, 75, 100, 200, and 400 mg/kg diet) for 60 days. The results show that dietary vitamin E supplementation could significantly increased the prawn weight (P < 0.05). The activity of superoxide dismutase (SOD) in the hepatopancreas was significantly higher in prawns fed with diets supplemented with ≤75 mg/kg vitamin E than in those fed with diets supplemented with 100–400 mg/kg vitamin E (P < 0.05). The activity of catalase (CAT) in the hepatopancreas decreased significantly as dietary vitamin E supplementation increased (P < 0.05), and no significant difference was detected in glutathione peroxidase (GSH-Px) activity between different dietary groups (P >0.05). The contents of vitamin E in the hepatopancreas and in the muscle increased with increasing dietary vitamin E. There was a linear correlation between the vitamin E level in diet and that in muscle, and between the vitamin E level in diet and that in the hepatopancreas. All the above results indicated that dietary vitamin E can be stored in the hepatopancreas and muscle and lower both the activities of SOD and CAT in the hepatopancreas, suggesting that it is a potential antioxidant in M. nipponense. Broken line analysis conducted on the weight gains of prawns in each diet group showed that the dietary vitamin E requirement for maximum growth is 94.10 mg/kg.     

Optimal content and ratio of lysine to arginine in the diet of Pacific white shrimp, Litopenaeus vannamei

The optimal quantity of dietary lysine (Lys) and arginine (Arg), and the optimal ratio of dietary Lys to Arg for Pacific white shrimp Litopenaeus vannamei were investigated. Coated Lys and Arg were added to a basal diet (37.99% crude protein and 7.28% crude lipid) to provide graded levels of Lys and Arg. The experimental diets contained three Lys levels (2.51%, 2.11%, and 1.70% of total diet), and three Arg levels (1.41%, 1.80%, and 2.21% of total diet) and all combinations of these levels were tested. Pacific white shrimp, with a mean weight of 3.62±0.1 g, were randomly distributed in 36 fiberglass tanks with 30 shrimp per tank and reared on the experimental diets for 50 days. After the feeding trial, the growth performance, survival, feed conversion rate (FCR), body composition and protease and lipase activities in the hepatopancreases of the experimental shrimps were determined. The results show that weight gain (WG), specific growth rate (SGR), FCR, body protein, body Lys and Arg content were significantly affected by dietary Lys and Arg (P <0.05) and improved when dietary Lys and Arg levels were 2.11% ～ 2.51% and 1.80%～2.21%, respectively. Protease and lipase activities in the hepatopancreases of the shrimps appeared higher when dietary Lys and Arg quantities were 2.11% ～2.51% and 1.80%～2.21%, although the difference was not statistically significant (P >0.05). Therefore, according to our results, the optimal Lys and Arg quantities in the diet of Pacific white shrimp, L. vannamei, were considered to be 2.11%–2.51% and 1.80%–2.21%, respectively, and the optimal ratio to be 1:0.88–1:1.05.