Preliminary Study of the Optimum Dietary Ascorbic Acid Level in Sea Cucumber,Apostichopus japonicus (Selenka)

A 14‐wk feeding trial was carried out to evaluate the optimum dietary ascorbic acid (AA) level in juvenile sea cucumber, Apostichopus japonicus. Sea cucumbers averaging 1.49 ± 0.07 g (mean ± SD) were randomly distributed into 18 rectangular plastic tanks of 20 L capacity in a recirculating system (20 animals per tank). Six semipurified experimental diets were formulated to contain 0 (l ‐ascorbyl‐2‐monophosphate [AMP]; AMP0), 30 (AMP24), 60 (AMP48), 120 (AMP100), 240 (AMP206), and 1200 (AMP1045) mg AA/kg diet in the form of AMP using casein as the main protein source. Sea cucumbers were fed each of the six experimental diets in triplicate groups. At the end of 14 wk of feeding trial, weight gain (WG), specific growth rate (SGR), and feed efficiency (FE) of sea cucumbers fed AMP100, AMP206, and AMP1045 were significantly (P < 0.05) higher than those of animals fed AMP0, AMP24, and AMP48. However, there were no significant differences in WG, SGR, and FE among sea cucumbers fed AMP100, AMP206, and AMP1045 and among animals fed AMP0, AMP24, and AMP48. Whole‐body vitamin C concentration increased with AA content of the diets. Broken‐line analysis of WG showed an optimum dietary AA level of 105.3 mg AA/kg diet in sea cucumber. These results indicated that the optimum dietary vitamin C level in sea cucumber in the form of AMP could be greater than 100 mg AA/kg diet but less than 105.3 mg AA/kg diet.     

Preliminary Study of the Dietary α‐Tocopherol Requirement in Sea Cucumber,Apostichopus japonicus

This study was conducted to evaluate the dietary α‐tocopherol (vitamin E) requirement in juvenile sea cucumber, Apostichopus japonicus. Sea cucumbers averaging 1.48 ± 0.07 g (mean ± SD) were randomly distributed into 18 rectangular plastic tanks of 20 L capacity in a recirculating system (20 animals per tank). Six semi‐purified experimental diets with average protein and crude lipid levels (dry matter) of 29.7 ± 0.36% and 4.39 ± 0.23% (mean ± SD), respectively were formulated to contain 0 (E4), 15 (E12), 30 (E23), 60 (E44), 120 (E77) and 600 (E378) mg α‐tocopherol/kg diet, supplied as dl‐α‐tocopheryl acetate. Diets were analyzed for α‐tocopherol content by HPLC and the α‐tocopherol levels were 4.01, 12.4, 23.1, 44.3, 77.4 and 378 mg α‐tocopherol/kg diet for E4, E12, E23, E44, E77 and E378 diets, respectively. Casein and defatted fish meal were used as the protein sources in the diets while wheat flour was the carbohydrate source. Sea cucumbers were fed each of the six experimental diets in triplicate groups. At the end of the 14‐week feeding trial, weight gain (WG), specific growth rate (SGR) and feed efficiency (FE) of sea cucumbers fed on E23, E44, E77 and E378 diets were significantly (P < 0.05) higher than those of animals fed on E4 and E12 diets. However, there were no significant differences in WG, SGR and FE among sea cucumbers fed on E23, E44, E77 and E378 diets or among those fed on E4 and E12 diets. Survival of sea cucumbers fed on E44, E77 and E378 diets were significantly higher than those of animals fed on E4, E12 and E23 diets. However, there were no significant differences among sea cucumbers fed on E4, E12 and E23 diets or among those fed on E44 and E77 diets. Whole‐body vitamin E concentration increased with α‐tocopherol content of the diets. Broken line analysis of WG showed an optimum dietary α‐tocopherol requirement of 41 mg α‐tocopherol/kg diet in sea cucumber. These results indicated that the optimum dietary α‐tocopherol requirement in sea cucumber in the form of dl‐α‐tocopheryl acetate could be higher than 23.1 mg α‐tocopherol/kg diet but lower than 44 mg α‐tocopherol/kg diet.     

Effect of replacing dietary fish meal with silkworm (Bombyx mori L) caterpillar meal on growth and non‐specific immunity of sea cucumber Apostichopus japonicus (Selenka)

The effect of dietary substitution of silkworm (Bombyx mori L) meal (SM) for fishmeal (FM) on the growth performance and non‐specific immunity of sea cucumber (Apostichopus japonicus) (initial weight: 12.8 ± 0.16 g) was determined. Four isonitrogenous and isocaloric diets were formulated: Diet 1, which served as the control diet, contained 5% FM; Diet 2 contained 3.75% FM and 1.25% SM; Diet 3 contained 2.5% FM and 2.5% SM; and Diet 4 contained 5% SM. Other ingredients in each of the four diets were kept in the same proportion. After 8 weeks of feeding, the results showed that sea cucumbers fed Diet 2 had 18.7% increases in weight over those fed the control diet, but no significant difference was observed. No obvious difference in body wall composition was detected among the sea cucumbers fed the four different diets. Immunity analysis indicated that phagocytosis and serum alkaline phosphatase activity were not significantly (P > 0.05) affected when FM was partially or completely replaced with SM. Serum lysozyme activity of sea cucumbers fed Diet 4 showed a significant (P < 0.05) growth increase compared with those fed control diet. The results revealed that SM could be an effective substitute for FM in sea cucumber diet.     

Effects of dietary heat‐killed Lactobacillus plantarum L‐137 (HK L‐137) on the growth performance,digestive enzymes and selected non‐specific immune responses in sea cucumber,Apostichopus japonicus Selenka

A feeding trial was conducted to evaluate the efficacy of dietary heat‐killed Lactobacillus plantarum L‐137 (HK L‐137) on growth performance, digestive, non‐specific immune and phagocytosis of sea cucumber, Apostichopus japonicus. Sea cucumbers (initial body weight 1.35 ± 0.04 g) were fed diets supplemented with five levels of HK L‐137 (0, 0.005, 0.025, 0.05 and 0.25 g HK L‐137 kg^?1 diets) for 60 days. Results indicated sea cucumbers fed with diets containing 0.05 and 0.25 g HK L‐137 kg^?1 diets showed significantly (P < 0.05) higher body weight gain and specific growth rate than other groups. Sea cucumbers fed with diets containing 0.05 and 0.25 g HK L‐137 kg^?1 diets showed significantly (P < 0.05) higher protease activity than control group. Higher amylase, lysozyme and phagocytic activities were found in 0.25 g HK L‐137 kg^?1 diet group. Higher superoxide dismutase enzyme and alkaline phosphatase activity was found in 0.05 g HK L‐137 kg^?1. While no significant differences (P > 0.05) were found in acid phosphatase activity. These results suggested that dietary supplementation of 0.05 g HK L‐137 kg^?1 diets would have benefit on growth, digestive enzymes and several non‐specific immune parameters of sea cucumber.     

Preliminary Study of the Optimum Dietary Riboflavin Level in Sea Cucumber,Apostichopus japonicus (Selenka)

A 14‐wk feeding trial was carried out to evaluate the optimum dietary riboflavin (vitamin B₂) level in juvenile sea cucumber, Apostichopus japonicus. A total of 360 sea cucumbers averaging 1.49 ± 0.07 g (mean ± SD) were randomly distributed into 18 rectangular plastic tanks, and each tank was then randomly assigned to one of three replicates of six diets containing 0.29 (B₂0), 4.22 (B₂4), 8.93 (B₂9), 17.9 (B₂18), 56.7 (B₂57), and 577 (B₂577) mg riboflavin/kg diet. At the end of 14 wk of feeding trial, average weight gain (WG) of sea cucumbers fed B₂9, B₂18, B₂57, and B₂577 diets were significantly (P < 0.05) higher than that of animals fed B₂0 diet. WG of sea cucumbers fed B₂18, B₂57, and B₂577 diets were significantly higher than those of animals fed B₂0 and B₂4 diets. Specific growth rate of sea cucumbers fed B₂9, B₂18, B₂57, and B₂577 diets were significantly higher than those of animals fed B₂0 and B₂4 diets. Feed efficiency of sea cucumbers fed B₂9, B₂57, and B₂577 diets were significantly higher than those of animals fed B₂0 and B₂4 diets. Although significant differences were recorded in proximate composition of sea cucumbers fed the experimental diets, no clear trends were observed. The ANOVA test suggested that the optimum dietary riboflavin level in sea cucumber could be 17.9 mg/kg diet but broken‐line analysis of WG indicated a level of 9.73 mg riboflavin/kg diet. Therefore, these results may indicate that the optimum dietary riboflavin level in sea cucumber could be higher than 9.73 mg/kg diet but lower than 17.9 mg/kg diet.     

Effectiveness of l‐ascorbyl‐2‐polyphosphate as an ascorbic acid source for sea cucumber,Apostichopus japonicus

A feeding trial was conducted to determine the adequate dietary ascorbic acid (AsA) levels and the effects on growth, meat quality and antioxidant status of sea cucumber (10.04 ± 0.06 g), Apostichopus japonicus. l ‐ascorbyl‐2‐polyphosphate (35% AsA equivalent) was supplemented separately to the basal diet to obtain five AsA levels, 0, 598, 1473, 4676 and 14340 mg kg^?1 diet respectively. After 60‐day feeding trial, the sea cucumbers fed diets containing 598 and 1473 mg AsA kg^?1 showed significantly higher (P < 0.05) body weight gain and specific growth rate values than the sea cucumbers fed control diets. The sea cucumbers fed diets containing 1473 and 4676 mg AsA kg^?1 showed significantly higher (P < 0.05) hydroxyproline contents than those of the sea cucumbers fed diets containing 0 and 598 mg AsA kg^?1. Antioxidant enzymes such as total antioxidant capacity, superoxide dismutase and glutathione peroxidase showed increasing trends with the increasing dietary AsA levels, but no significant differences (P > 0.05) were observed when the sea cucumbers fed diets with high dietary AsA levels. The content of malondialdehyde had the opposite trend of antioxidant enzymes. In conclusion, the adequate dietary AsA level focusing on growth performance of sea cucumber is between 598 and 1473 mg kg^?1 diet. Furthermore, high level of dietary AsA (between 598 and 4676 mg kg^?1 diet) improved meat quality and antioxidant status.     

Effects of butyrate glycerides supplementation in high soybean meal diet on growth performance,intestinal morphology and antioxidative status of juvenile black sea bream,Acanthopagrus schlegelii

This study aimed to investigate the effects of graded butyrate glyceride (BG) supplementation levels in high soybean meal diet on juvenile black sea bream. Three hundred and sixty fish were fed diets containing 199 g/kg fishmeal and 450 g/kg soybean meal, with increasing levels of BG at 0, 2, 4, 6, 8 or 16 g/kg for eight weeks. The growth performance of the fish increased with increasing dietary BG supplementation up to 6 g BG/kg, beyond which growth rate reduced significantly (p < .05). Dietary BG supplementation increased the intestinal protease activity, but had no significant (p > .05) effect on lipase and amylase activities. Fish fed the basal diet exhibited villus shortening with a decrease in the number of goblet cells and a reduction in absorptive and digestive epithelial surface, while fish fed ≥4 g BG/kg diets showed a well‐integrated gut, with large absorptive and digestive epithelial surface. Dietary BG supplementation also improved antioxidative capacity by increasing superoxide dismutase and glutathione peroxidase activities while decreasing malondialdehyde content. The inclusion of BG in high soybean meal diets can improve growth performance, maintain healthy gut morphology and enhance antioxidative capacity of black sea bream.     

Optimum Level of Dietary n‐3 Highly Unsaturated Fatty Acids for Juvenile Sea Cucumber,Apostichopus japonicus

A feeding trial was conducted to estimate the optimum level of dietary n‐3 highly unsaturated fatty acids (HUFAs) for juvenile sea cucumber, Apostichopus japonicas, based on growth performance and fatty acid compositions. Diets with five n‐3 HUFAs levels (0.15, 0.22, 0.33, 0.38, and 0.46%) were fed to sea cucumber juveniles (1.97 ± 0.01 g) once a day for 60 d. The sea cucumbers fed diets containing 0.22% n‐3 HUFAs showed significantly (P < 0.05) higher body weight gain, feed efficiency, and protein efficiency ratio than the sea cucumbers fed diets containing 0.15% n‐3 HUFAs, but not significantly different (P > 0.05) from those of sea cucumbers fed diets containing 0.33, 0.38, and 0.46% n‐3 HUFAs. The sea cucumbers fed diets containing 0.46% n‐3 HUFAs showed significantly (P < 0.05) higher eicosapentaenoic acid and saturated fatty acid than the sea cucumber fed diets containing 0.15% n‐3 HUFAs, but not significantly different (P > 0.05) from those of sea cucumbers fed diets containing 0.22, 0.33, and 0.38% n‐3 HUFAs. The results of growth performance and n‐3 HUFA compositions of body wall indicated that the optimum level of dietary n‐3 HUFAs for juvenile sea cucumber is between 0.22 and 0.46%.     

饲料中浒苔添加量以及处理方法对幼刺参生长、消化率、消化酶和非特异性免疫酶的影响

采用单因素实验设计,先配制6种浒苔含量(0、5％、10％、15％、20％和25％)饲料饲养初始体质量(1.44±0.01)g幼刺参49 d,然后根据浒苔含量实验结果配制20％含量、3种方法处理的浒苔[干燥粉碎(DC)、纤维素酶酶解后干燥粉碎(DCC)和蛋白酶酶解后干燥粉碎(DCP)]饲料饲养初始体质量(4.58 ±0.23)g幼刺参60 d,以研究饲料中浒苔添加量以及处理方式对幼刺参生长、消化率、消化酶和非特异性免疫酶的影响.实验每组饲料设3个重复,每个重复饲喂35头刺参.结果显示:(1)浒苔对提高刺参特定生长率(SGR)、肠道淀粉酶(AMS)活性和超氧化物歧化酶(SOD)和降低饲料系数(FCR)有显著作用(P＜0.05),其中20％浒苔含量最好,浒苔能显著降低饲料干物质表观消化率(ADCd)和粗蛋白质表观消化率(ADCp)(P＜0.05),对刺参摄食率(FI)、成活率(SR)、肠道胃蛋白酶(PP)活性和酸性磷酸酶(ACP)无显著性影响(P＞0.05).(2)3种方法处理的浒苔中,DCC和DCP浒苔对提高刺参SGR、ADCd、ADCp、肠道AMS、PP、SOD和ACP活性和降低FCR有显著作用(P＜0.05),其中DCC浒苔最好,3种方法处理的浒苔对刺参FI和SR亦无显著性影响(P＞0.05).在本实验条件下,幼刺参饲料中浒苔适宜含量为20％;纤维素酶酶解后干燥粉碎浒苔是一个理想的浒苔处理方法.     

Effects of differently processed diets on growth,immunity and water quality of the sea cucumber,Apostichopus japonicus (Selenka, 1867)

The type of formulated diet used in aquaculture systems affects the feed efficiency and water quality. In this study, the water quality, growth performance and immunity of the sea cucumber, Apostichopus japonicus (Selenka, 1867), fed diets produced using four different processing methods (extruded pellet diet, cold‐bonded pellet diet, flake diet and mash diet) were quantified for 60 days to identify the optimal feed type for culturing of this species. Sea cucumbers grew faster, the feed conversion ratio was much lower, and immunity indicators were higher when fed the extruded pellet diet compared to the other diets. Sea cucumbers fed the extruded pellet diet had the highest specific growth rate (0.96), whereas A. japonicus fed the cold‐bonded pellet diet had the lowest specific growth rate (0.51). The lysozyme activity of sea cucumbers fed the extruded pellet diet was higher (57.52) than that of A. japonicus fed the cold‐bonded pellet diet (39.22), flake diet (37.32) and mash diet (32.68). When animals were fed the mash diet, the ammonia–nitrogen, nitrite–nitrogen and phosphate productions were higher than in animals fed the other diets. These results indicate that the extruded pellet diet is the optimum feed type for use in the culture of A. japonicus.     

四种不同添加物对仿刺参非特异性免疫力和肠道免疫基因Aj-p105、Aj-p50、Aj-rel和Aj-lysmRNA表达的影响

本实验研究了饲料中添加酵母多糖(6.3 g/kg)、马氏副球菌(109 cfu/kg)、大黄(25.0 g/kg)和氟苯尼考(15.0 mg/kg)4种添加物对仿刺参[初始体质量(4.68±0.36)g]非特异性免疫力以及肠道组织免疫相关基因Aj-p105、Aj-p50、Aj-rel和Aj-lys mRNA表达的影响.每个处理分别设置5个重复,以投喂未添加上述任何成份的基础饲料组作为空白对照,养殖实验周期为60 d.结果发现,饲料中添加马氏副球菌能显著提高仿刺参体腔细胞的吞噬活性和呼吸爆发活力,而添加酵母多糖可以显著提高仿刺参体腔细胞的吞噬能力,但是添加氟苯尼考显著降低了仿刺参体腔细胞的呼吸爆发活力;而在仿刺参中肠肠道组织中,酵母多糖和马氏副球菌处理组免疫基因Aj-p105和j-p50 mRNA的表达均大幅上调,显著高于对照组.其中,酵母多糖添加组增幅分别为43.2％和63.1％,马氏副球菌添加组的增幅分别为49.8％和48.0％.马氏副球菌添加组中免疫基因Aj-lys的表达显著高于对照组,增幅为46.4％;大黄添加组中Aj-p105 mRNA的表达量显著高于对照组,而氟苯尼考添加组中Aj-p50、Aj-rel和Aj-lys的mRNA表达量相对于对照组均显著下降.研究表明,饲料中适当添加酵母多糖和马氏副球菌可有效提高仿刺参非特异性免疫力,而饲料中抗生素氟苯尼考的添加会降低仿刺参非特异性免疫力.     

Optimum dietary protein and lipid levels for growth of juvenile sea cucumber Apostichopus japonicus

A feeding trial of three protein (200, 300 and 400 g kg⁻¹) and two lipid levels (20 and 100 g kg⁻¹) was conducted to determine the proper dietary protein and lipid levels for growth of juvenile sea cucumber Apostichopus japonicus. Dietary protein and lipid levels were adjusted by adding with different levels of soybean meal, squid liver oil and soybean oil, respectively. Three replicate groups of sea cucumbers (average weight of 1.3 g) were fed the experimental diets for 12 weeks. At the end of the feeding trial, survival was not affected by dietary protein and lipid levels (P > 0.05). Weight gain (WG) and specific growth rate (SGR) of sea cucumbers were significantly affected by dietary protein (P < 0.006) and lipid levels (P < 0.001). The highest WG and SGR were observed in sea cucumbers fed the 200 and 400 g kg⁻¹ protein diet with 20 g kg⁻¹ lipid (P < 0.05). WG and SGR of sea cucumbers fed the diet containing 20 g kg⁻¹ lipid were higher than those of sea cucumbers fed the 100 g kg⁻¹ lipid diets (P < 0.05) at each dietary protein level. Apparent digestibility coefficients of dry matter, crude protein, carbohydrate and gross energy of sea cucumbers fed the 20 g kg⁻¹ lipid diets were significantly higher than those of the 100 g kg⁻¹ lipid diets at 200 and 400 g kg⁻¹ protein (P < 0.05). Moisture, crude protein, crude lipid and ash contents were not significantly different among the groups. The results of this study indicate that the diet containing 200 g kg⁻¹ protein (170 g kg⁻¹ digestible protein) with 20 g kg⁻¹ lipid (13 g kg⁻¹ digestible lipid) may be sufficient for optimum growth of juvenile sea cucumber.     

几种饲料原料对刺参幼参生长和体成分的影响

研究了不同饲料原料对刺参Apostichopus japonicus(Selenka)幼参生长和体成分的影响.实验采用鱼粉、鼠尾藻Sargassum thunbergii Kuntze、浒苔Enteromorpha prolifera、海带Laminaria japonica和海泥5种主要原料配制的饲料投喂体长为4.18±0.23cm、体重为5.99±0.26g的刺参幼参,进行了为期80d的养殖实验.实验结束时,投喂鼠尾藻饲料、浒苔饲料和动物性饲料的刺参特定生长率(SGR)分别为95.36%/d、92.29%/d和84.87%/d.这三者之间无显著差异,但生长效果要好于投喂海带饲料和海泥饲料的刺参.实验结果表明,在特定的室内养殖条件下,虽然刺参能够更好地利用植物性蛋白,但是可以将动物性蛋白作为刺参的辅助性饲料成分,配制出营养更全面的配合饲料;浒苔作为刺参幼参的养殖饲料原料是完全可行的;海带粗加工产品不适于用做刺参饲料的主要成分.     

Dietary supplements of guanosine improve the growth,non‐specific immunity of sea cucumber,Apostichopus japonicus Selenka,and its resistance against Vibrio splendidus

The growth response, non‐specific immune activities and disease resistance were measured in sea cucumber, Apostichopus japonicus Selenka (initial average weight 6.80 ± 0.10 g), when fed diets supplemented with graded levels of guanosine from the guanosine‐5’‐monophosphate disodium (GMP) at 0 (control), 0.3, 0.6 and 1.2 g/kg for 8 weeks. The results showed that GMP supplemented at 0.6 and 1.2 g/kg significantly enhanced the growth of sea cucumber. Sea cucumber fed a diet with 0.6 g/kg of GMP had significantly higher intracellular superoxide anion production, nitric oxide synthase activity, lysozyme activity and the total superoxide dismutase (T‐SOD) activity than those in control group (p < .05). Increased lysozyme activity and T‐SOD activity were also found in sea cucumber fed GMP at 1.2 g/kg. Moreover, there was significantly lower cumulative mortality after the disease challenge in sea cucumber fed the diets with 0.6 and 1.2 g/kg GMP than that in control and 0.3 g/kg GMP groups (p < .05), and no significant difference was observed between 0.6 and 1.2 g/kg GMP groups. These results suggested that feeding GMP at a dose of 0.6 g/kg could enhance growth, non‐specific immunity of sea cucumber as well as its resistance against Vibrio splendidus.     

饲料中添加浒苔对仿刺参幼参生长、消化酶活性和免疫力的影响

在水温17~18℃和盐度30条件下,将初始体质量为(4.09±0.26)g的仿刺参饲养在15个循环水玻璃缸(容积100L)中,投喂在基础饲料中添加0%、3%、6%、9%和12%浒苔的饲料,于投喂后第7、14、28d和42d分别检测仿刺参的生长指标、消化酶(蛋白酶、淀粉酶、纤维素酶和褐藻酸酶)和体腔液免疫酶(溶菌酶、酸性磷酸酶、碱性磷酸酶和超氧化物歧化酶)的活性。试验结果表明,投喂试验饲料后第14、28d和42d:(1)饲料中添加6%和9%浒苔组仿刺参的特定生长率显著增加(P0.05),在不同取样时间其他添加组仿刺参的的特定生长率与对照组差异不显著(P0.05);(2)饲料中浒苔添加量为6%和9%试验组仿刺参的4种消化酶比活力显著高于对照组(P0.05),其中6%组仿刺参的消化酶比活力最高;(3)饲料中浒苔添加量为6%时,仿刺参溶菌酶活力显著高于对照组及其他试验组(P0.05);饲料中浒苔添加量为6%和9%时,仿刺参碱性磷酸酶活力和超氧化物歧化酶活力显著高于对照组及其他试验组(P0.05);添加浒苔可以显著提高酸性磷酸酶活力,至第42d,试验组酸性磷酸酶活力高于对照组(P0.05),且浒苔添加量为6%时活力最高。在本试验条件下,饲料中添加浒苔可以提高仿刺参的特定生长率、消化酶活力及免疫力,浒苔的最适添加量为6%~9%。     

Effects of dietary peptide intake on growth,energy budget,body composition and non‐specific immunity of the sea cucumber Apostichopus japonicus (Selenka)

In this study, a 60‐day feeding trial was conducted to determine the effects of feed supplementating the feed of Apostichopus japonicus with peptides on its growth, energy budget, body composition and immune responses. Sea cucumbers were fed with five experimental diets supplemented with different proportions of peptides: 0 (D1), 12.5 (D2), 25 (D3), 37.5 (D4) and 50 (D5) g/kg in basal diet. Our results suggested that specific growth rate (SGR) and ratio of viscera to body wall (RVBW) of sea cucumbers fed with D4 were significantly improved. Relative to D1, ingestion rate (IR) and faeces production rate (FPR) for D3 and D4 were reduced considerably. Notably, the energy intake increased when peptide level increased from 0 to 50 g/kg. Meanwhile, the energy deposited for growth increased, and the energy loss decreased when peptide level increased from 0 to 37.5 g/kg. The sea cucumbers in D4 had the highest level of crude fat and lowest crude ash. The activities of immunoenzyme, such as SOD, CAT, T‐AOC, ACP and AKP, increased with peptide increase. Results suggested that supplementation of the feed with 25–37.5 g/kg peptides could significantly improve the growth performance, body composition and immune capacity of Apostichopus japonicus.     

Effects of Dietary Lysine Levels on Growth,Intestinal Digestive Enzymes,and Coelomic Fluid Nonspecific Immune Enzymes of Sea Cucumber,Apostichopus japonicus,Juveniles

A 56‐d feeding trial was conducted to evaluate the effects of dietary lysine levels on growth performance, intestinal digestive enzymes, and nonspecific immune response of Apostichopus japonicus juveniles. Five semipurified diets were formulated to contain graded levels of lysine (from 0.28 to 2.32% of dry matter). Although no significant differences (P > 0.05) were observed in survival rate, final weight (FW), and body weight gain (BWG), the FW and BWG increased from 0.28 to 1.19% with increasing dietary lysine levels, then showed a declining tendency. Broken‐line regression analysis of BWG indicated sea cucumber requires lysine at 0.76% of dry diet. Proximate composition, lysine content of the body wall, and total amino acid profiles were not affected by dietary treatments. Intestinal protease level increased with increasing dietary lysine level from 0.28 to 1.19%, then decreased. Acid phosphatase and superoxide dismutase activities of the sea cucumbers were not affected by various dietary lysine levels; however, significantly (P < 0.05) higher alkaline phosphatase activity was observed in sea cucumbers fed 2.32% lysine diet than those fed diets having 0.28 and 1.89% lysine. Overall, sea cucumber juveniles fed with diets containing between 0.76 and 1.19% lysine showed better growth performance, digestive enzymes, and nonspecific immune enzyme activities.     

Interactive Effects of Vitamin C and E Supplementation on Growth,Fatty Acid Composition,and Lipid Peroxidation of Sea Cucumber,Apostichopus japonicus,Fed with Dietary Oxidized Fish Oil

A feeding trial was conducted to determine the interactive effects of vitamin C (ascorbic acid, AsA) and E (α‐tocopherol, α‐Toc) supplementation with dietary oxidized fish oil (OFO) on the growth performance, whole‐body AsA, and α‐Toc concentrations and fatty acid composition of juvenile sea cucumber. In a 9‐wk feeding trial, juveniles (average weight: 0.6 ± 0.1 g) were cultured in twenty‐four 50‐L tanks (30 juveniles per tank) in triplicate, and fed with eight test diets containing two levels of OFO (8.9 and 156.9 meq/kg) with varying levels of vitamin C (500 and 1000 mg AsA equivalents/kg diet) and E (100 and 200 mg α‐Toc equivalents/kg diet) supplementation, respectively. Body weight gain of sea cucumber was significantly reduced by dietary OFO, while mortality and whole‐body thiobarbituric acid‐reactive substances value were increased significantly. Increasing dietary vitamin C and E levels significantly increased whole‐body α‐Toc and AsA concentrations, respectively. A high level of vitamin E combined with OFO led to consumption of AsA. Even with supplementation of a large dose of vitamin C and/or E in diets, growth performance could not be improved, probably due to the high levels of vitamins in the control diets.     

Effect of dietary chitosan oligosaccharide complex with Ce (IV) on growth,immunity and disease resistance against Vibrio splendidus of sea cucumber,Apostichopus japonicas

An 8‐week feeding trial was conducted to investigate the effects of dietary chitosan oligosaccharide complex with cerium (Ce IV) (COS‐Ce) on growth performance, nonspecific immunity and disease resistance of sea cucumber, Apostichopus japonicas. Five isonitrogenous (18.6%) and isolipidic (1.1%) practical diets were formulated with graded level of COS‐Ce (0, 150, 300, 600 and 1200 mg kg^?1 dry feed), which were named as COS‐Ce/0, COS‐Ce/150, COS‐Ce/300, COS‐Ce/600, COS‐Ce/1200 respectively. Each diet was allocated to four replicates of sea cucumbers (Initial weight: 6.72 ± 0.02 g). Sea cucumbers were fed to apparent satiation once daily (19:00 hours) for 56 days. During the experiment, water temperature was kept at 16 ± 0.5°C, pH 7.8–8.2, dissolved oxygen beyond 5 mg L^?1, ammonia nitrogen below 0.5 mg L^?1 and salinity from 30‰ to 31‰. Results showed that the specific growth rate of sea cucumbers was significantly higher in COS‐Ce/600 than that in other four treatments. Activities of phagocytosis, respiratory burst, acid phosphatase and alkaline phosphatase in COS‐Ce/600 were significantly higher than that in COS‐Ce/0 (P < 0.05) respectively. On the contrary, cumulative mortality was the lowest in COS‐Ce/600 following 14 days exposure to Vibrio splendidus (P < 0.05). In conclusion, these results confirmed that dietary COS‐Ce had beneficial effects on growth performance, nonspecific immunity and disease resistance of sea cucumber.     

Effect of dietary carbohydrate levels on growth performance,non‐specific immune enzymes and acute response to low salinity and high temperature of juvenile sea cucumber Apostichopus japonicus

This study was performed to determine the optimum dietary carbohydrate (CHO) levels of sea cucumber, based on the parameters of growth, digestive enzymes, digestibility, non‐specific immune enzymes and acute low‐salinity (20 g/L) stress and high‐temperature (30°C) stress tolerance. Diets with eight different CHO (dextrin) levels (32.9, 107.6, 192.5, 257.2, 316.8, 428.0, 482.4 and 572.8 g/kg) were fed to sea cucumber juveniles (0.49 ± 0.01 g) for 60 days. Significant higher amylase activity was observed in sea cucumbers fed diet with CHO ranging between 32.9 and 192.5 g/kg than that of other treatments (p < .05). The sea cucumbers fed with 192.5 g/kg CHO showed significantly higher acid phosphatase activity than the treatments of 482.4 and 572.8 g/kg CHO (p < .05), and significantly higher alkaline phosphatase activity than other treatments (p < .05, except 257.2 g/kg). The treatments of 428.0–572.8 g/kg were found significantly lower values than other treatments in apparent digestibility coefficients for dry matter and crude protein (p < .05). The sea cucumbers fed with 192.5, 257.2 and 316.8 g/kg CHO showed better tolerance to high‐temperature (30°C) and low‐salinity (20 g/L) stress than other treatments. In brief, the optimal dietary CHO level for the growth of juvenile sea cucumber is 177.96 g/kg. However, excessive CHO will inhibit amylase enzyme activity and decrease digestibility, resulting in low growth of sea cucumber.