Effectiveness of l‐ascorbyl‐2‐monophosphate Na/Ca as a vitamin C source for yellowtail Seriola quinqueradiata juveniles

A feeding experiment was conducted to examine the efficacy of a vitamin C (L‐ascorbic acid, AsA) derivative, l ‐ascorbyl‐2‐monophosphate Na/Ca (AMP‐Na/Ca) by comparing to l ‐ascorbyl‐2‐monophosphate‐Mg (AMP‐Mg) in terms of growth, AsA content in tissues, and hematology in yellowtail Seriola quinqueradiata juvenile (1.10 ± 0.01 g). Furthermore, a stress resistance test for the species fed AMP‐Na/Ca was also conducted. In experiment 1, 11 test pellet diets with different levels of AMP‐Na/Ca (0, 12, 43, 88, 440 and 881 mg AsA kg^?1diet) and AMP‐Mg (0, 16, 52, 106, 595 and 1164 mg AsA kg^?1 diet) were formulated and fed to the yellowtail three times per day for 50 days. In both the vitamin C sources, the survival rates of the fish fed diets without supplemental AsA were lower than 50% at day 20, and more than 50% mortality occurred in fish that fed the diets containing 12 or 16 mg AsA kg^?1 after day 30. However, no significant differences were detected in survival and growth among fish that fed the diets containing more than 43 mg AsA kg^?1. Liver and brain AsA concentrations generally increased with increasing dietary AsA level in both sources. In experiment 2, test diets were formulated to contain 43, 88, 440 and 881 mg AsA kg^?1 using AMP‐Na/Ca, and after 60 days of feeding, yellowtail juveniles were subjected to low salinity and air exposure stress. The fish that received diets with 440 mg AsA kg^?1 showed significantly higher tolerance to low salinity stress and higher survival rate in air exposure stress than those of other groups. The present study demonstrated that yellowtail juveniles could utilize AMP‐Na/Ca as an AsA source like AMP‐Mg, and that supplementation of 43–52 mg AsA kg^?1 diet was optimum for normal growth. However, this study showed that dietary inclusion of 440 mg AsA kg^?1 would be necessary to improve stress resistance of this species.     

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.     

Interactive effects of dietary vitamin C and phospholipid in micro‐bound diet for growth,survival, and stress resistance of larval red sea bream,Pagrus major

This study was conducted to examine the effects of dietary ascorbic acid (AsA) and phospholipid (PL) and their interaction on growth, survival, and stress resistance in red sea bream larvae. Twenty‐six days old red sea bream were fed nine micro‐bound diets supplemented three levels of AsA (0, 800 and 1600 mg kg^?1 diet) and PL (0, 20 and 40 g kg^?1 diet) for 15 days. Dietary AsA and PL were both significant factors on survival rates. There was also an interaction between dietary AsA and PL on survival rate (P < 0.05). The larvae fed 800 or 1600 mg kg^?1 AsA with 40 g kg^?1 PL diets showed the highest survival rate, with values similar to those of the live‐food supplemented group. Stress resistance against low salinity exposure significantly increased with increased dietary level of AsA and PL. However, significant interaction of AsA and PL was not detected. The larvae fed 1600 mg kg^?1 AsA with 40 g kg^?1 PL diet showed the highest stress resistance among all diets, but it was not significantly different than that of larvae fed 800 mg kg^?1 AsA with 40 g kg^?1 PL diet. This study clearly demonstrated that combined use of AsA and PL can improve survival of 26–40 days posthatching red sea bream larvae. Moreover, the present study suggested that 800 mg kg^?1 AsA with 40 g kg^?1 PL in diet was needed for producing high quality seedling under the stressful conditions.     

Requirements of vitamin C (L-ascorbyl-2-monophosphate-Mg and L-ascorbyl-2-monophosphate-Na) and its effects on immune responses of grouper, Epinephelus malabaricus

An 8‐week feeding trial was conducted to evaluate two vitamin C derivatives, L‐ascorbyl‐2‐monophosphate‐Mg (C2MP‐Mg) and L‐ascorbyl‐2‐monophosphate‐Na (C2MP‐Na), to satisfy the vitamin C requirement and to test their effects on the immune responses of juvenile grouper, Epinephelus malabaricus. C2MP‐Mg and C2MP‐Na were each supplemented at 20, 50, 80, 150, 250, and 400 mg kg^?1 diet in the basal diet providing of 7, 18, 31, 51, 93, 145 mg ascorbic acid (AA) equivalent of C2MP‐Mg kg^?1 diet and 4, 10, 17, 31, 47, 77 mg ascorbic acid (AA) equivalent of C2MP‐Na kg^?1 diet, respectively. Basal diet without AA supplementation was included as control. Each diet was fed to triplicate groups of grouper (mean initial weight 3.20 ± 0.05 g). Fish fed diets supplemented with either C2MP‐Mg or C2MP‐Na had significantly (P < 0.05) greater weight gain (WG), feed efficiency and survival than those fed the unsupplemented control diet. Liver ascorbate concentrations in fish generally increased as dietary C2MP‐Mg or C2MP‐Na supplementation level increased. Haemolytic complement activity was higher in fish fed diets supplemented with 92 mg AA equivalent of C2MP‐Mg kg^?1 or 10–17 mg AA equivalent of C2MP‐Na kg^?1 than fish fed the unsupplemented control diet. Lysozyme activity was higher in fish fed ≥51 mg AA equivalent of C2MP‐Mg kg^?1 or ≥47 mg AA equivalent of C2MP‐Na kg^?1 than fish fed the unsupplemented control diet. Analysis by broken‐line regression of WG indicated that the adequate dietary vitamin C concentration from each vitamin C derivative in growing grouper is 17.9 mg AA equivalent of 2MP‐Mg kg^?1 and 8.3 mg AA equivalent of C2MP‐Na kg^?1, and it also indicated that C2MP‐Mg is about 46% as effective as C2MP‐Na in meeting the vitamin C requirement of grouper.     

Dietary nucleotide supplementation enhances growth and immune responses of grouper,Epinephelus malabaricus

Basal diet containing 0.5, 1.0, 1.5 and 2.0 g kg^?1 mixture of inosine monophosphate (IMP), adenosine monophosphate (AMP), guanosine monophosphate (GMP), uridine monophosphate (UMP) and cytidine monophosphate (CMP) (1 : 1 : 1 : 1 : 1) (mixed‐NT; Experiment 1) and 1.5 g kg^?1 from each nucleotides and mixed‐nucleotides (NT; Experiment 2) were fed to triplicate groups of grouper for 8 weeks. Basal diet without NT was used as control in both Experiments. In Experiment 1, fish fed the diet with 1.5 g mixed‐NT kg^?1 had higher (P < 0.05) weight gain (WG) than the control group. The superoxide anion (O₂^?) production ratio was higher in fish fed diets with 1.0–1.5 g mixed‐NT kg^?1 than the fish fed diets with ≤0.5 g mixed‐NT kg^?1. In Experiment 2, fish fed diets with nucleotides had higher WG than the control group. The O₂^? production ratio was higher in fish fed the diet with 1.5 g AMP kg^?1, followed by fish fed diets with 1.5 g UMP and mixed‐NT kg^?1, and lowest in the control group. These results suggest that growth and immune responses were enhanced in grouper fed diet with 1.5 g mixed‐NT kg^?1 diet. Diet with 1.5 g kg^?1 of AMP seems to be more beneficial on the immune responses in fish than other nucleotides.     

Effects of Dietary Vitamin C on Blood Chemistry and Nonspecific Immune Response of Juvenile Red Sea Bream,Pagrus major

A trial was conducted to determine the effect of ascorbyl‐2‐monophosphate Na/Ca (AMP‐Na/Ca) on blood chemistry and nonspecific immune response of red sea bream juveniles. Test diets with three levels of AsA (free, 107, and 325 mg/kg diet) were fed to juvenile red sea bream (36.0 ± 1.3 g) two times a day for 3 wk. There were no significant differences in hematocrit, glucose, and blood urea nitrogen. Total cholesterol and triglyceride in plasma of fish fed AsA‐free diet was significantly (P < 0.05) higher than that of fish fed two other diets. There were no significant differences in serum albumin, total bilirubin, and total serum protein. Glutamyl oxaloacetic transaminase in serum of fish fed diets containing 107 and 325 mg of AsA were significantly (P < 0.05) lower than that of fish fed AsA‐free diet. Serum lysozyme activity (LA) of fish fed diets containing 107 and 325 mg of AsA were significantly (P < 0.05) higher than that of fish fed AsA‐free diet. There was no significant difference in mucus LA. The results mentioned above demonstrated that AMP‐Na/Ca is a bioavailable AsA source for red sea bream juveniles. Supplement of more than 107 mg AsA/kg in diets improved blood chemistry and nonspecific immune function of red sea bream juveniles.     

Influence of dietary phospholipids level on growth performance,body composition and lipid class of early postlarval Litopenaeus vannamei

One experiment was conducted to determine the nutritive value of phospholipids on growth performance of early postlarval shrimp, Litopenaeus vannamei. Five isoenergic and isonitrogenous diets with five supplemented levels of phospholipids (P1, P2, P3, P4 and P5 with 0, 10, 20, 40 and 80 g kg^?1 diet, respectively) were fed to triplicate groups of L. vannamei (mean initial wet weight 0.8 mg) for 27 days. After the 27‐day feeding trial, the lowest weight gain (WG, %) and specific growth rate (SGR, % day^?1) was found in P1 treatment, the highest WG and SGR was found in P3, P4 and P5 treatments, P2 treatment provided intermediate result and showed significant difference compared to P1, P3, P4 and P5 treatments. Shrimp fed the P1 diet had significantly lower survival than shrimp fed other diets, while no significant difference was found in survival among P2, P3, P4 and P5 treatments. Broken‐line analysis on WG indicated that the optimum dietary phospholipids for early postlarval shrimp, L. vannamei, is 45.96 g kg^?1 diet.     

Evaluation of l-ascorbyl-2-glucose as the source of vitamin C for juvenile Korean rockfish Sebastes schlegeli (Hilgendorf)

This study was conducted to compare l ‐ascorbyl‐2‐glucose (AA2G) with l ‐ascorbyl‐2‐monophosphate‐Na/Ca (AMP‐Na/Ca) for supplying the dietary vitamin C for juvenile Korean rockfish Sebastes schlegeli (Hilgendorf). Fish were fed one of seven semi‐purified diets containing equivalents of 0, 50, 100 and 200 mg ascorbic acid (AA) kg^?1 diet in the form of AA2G or AMP‐Na/Ca for 12 weeks. After 12 weeks of feeding, weight gain, feed efficiency ratio and survival of fish fed the vitamin C‐free diet were significantly lower than those of fish fed the vitamin C‐supplemented diets in either form. The hepatosomatic index, condition factor and survival of fish fed AMP‐Na/Ca₁₀₀, AMP‐Na/Ca₂₀₀, AA2G₁₀₀ and AA2G₂₀₀ diets were significantly higher than fish fed the vitamin C‐free diet. After 9 weeks of feeding, fish fed the vitamin C‐free diet began to show vitamin C deficiency signs such as anorexia and lethargy. At the end of the 12‐week feeding trial, fish fed the vitamin C‐free diet exhibited vitamin C deficiency signs, e.g., anorexia, scoliosis, exophthalmia and fin haemorrhage. Vitamin C retention in the muscle and liver was similar to those of fish fed AA2G‐ or AMP‐Na/Ca‐supplemented diets. In general, there was no significant difference in the muscle and liver vitamin C concen‐tration in fish fed the AA2G and AMP‐Na/Ca diets at the same supplementation levels.     

Effect of dietary cornstarch levels on growth performance, digestibility and microscopic structure in the white shrimp, Litopenaeus vannamei reared in brackish water

The ability of Litopenaeus vannamei (initial mean weight: 0.96 ± 0.02 g) to utilize different levels of cornstarch was examined in terms of growth indices, body composition, digestibility and microscopic structure of the hepatopancreas. Six isonitrogenous semipurified diets were fed to satiation to shrimp for 8 weeks in triplicate tanks (30 shrimps per tank) connected to a natural brackish water (6–8 g L^?1) recirculating system. Diets contained different levels of cornstarch (100, 150, 200, 250, 300 and 350 g kg^?1) as the source of carbohydrate and were balanced using cellulose. Weight gain (WG), survival rate and feed conversion rate (FCR) were considerably affected by cornstarch levels of diets. The highest WG (453.6 g kg^?1) and best FCR was observed in shrimp fed the 150 g kg^?1 (cornstarch level) diet and was significantly (P < 0.05) higher than those fed diets containing 250–350 g kg^?1 cornstarch. However, the survival rate reached maximum in shrimp fed the 100 g kg^?1 diet (96.7), some 30% higher than the lowest rate, which was found in shrimp fed the 250 g kg^?1 diet. Body lipid tended to be higher in shrimp fed diets with higher cornstarch levels. The apparent digestibility of dry matter and crude fat increased with increasing levels of cornstarch and, hence, decreasing levels of cellulose. In addition, histological study on shrimp fed 10–350 g kg^?1 diets exhibited histological changes. The overall conclusion was that the optimum cornstarch level may be set at 100–200 g kg^?1 when the diets contain 380 g kg^?1 protein.     

Effects of dietary protein and lipid levels on growth and energy productive value of pacific white shrimp,Litopenaeus vannamei,at different salinities

A 8‐week feeding experiment was conducted to evaluate the effect of different dietary protein and lipid levels on growth and energy productive value of juvenile Litopenaeus vannamei, at 30 and 2 ppt, respectively. Nine practical diets were formulated to contain three protein levels (380, 410 and 440 g kg^?1) and three lipid levels (60, 80 and 100 g kg^?1). Each diet was randomly fed to triplicate groups of 30 shrimps per tank (260 L). The effects of salinity and an interaction between dietary protein level and lipid level on growth and energy productive value of shrimp were observed under the experimental conditions of this study. At 30 ppt seawater, shrimp fed with 440 g kg^?1protein diets had significantly higher weight gain (WG) than those fed with 380 g kg^?1 protein diets at the same dietary lipid level, and the 60 g kg^?1 lipid group showed higher growth than 80 g kg^?1and 100 g kg^?1 lipid groups at the same dietary protein level. At 2 ppt seawater, the growth of shrimp was little affected by dietary protein treatments when shrimp fed the 80 and 100 g kg^?1 lipid, shrimp fed the 80 g kg^?1 lipid diets had only slightly higher growth than that fed 60and 100 g kg^?1 lipid diets when fed 380 and 410 g kg^?1 dietary protein diets. A significant effect of salinity on growth of shrimp was detected with the growth responses at 30 ppt > 2ppt (P < 0.05). Final body lipid content, body protein content and energy productive value of shrimp was significantly higher in animals exposed to 30 ppt than in shrimp held at 2 ppt.     

Dietary phosphatidylcholine requirements in larval and postlarval Penaeus japonicus Bate

Three nutritional experiments were carried out to investigate the effect of dietary phosphatidylcholine (PC) on the growth (length, weight and metamorphosis) and survival (rearing and stress) of larval and postlarval Penaeus japonicus Bate. Purified soybean phosphatidylcholine (SPC, 95% purity), hen egg-PC (EPC, 94% purity), and de-oiled soybean lecithin (DSL, PC 23% purity) were used as sources of dietary PC. The results indicated that optimal metamorphosis in larval P. japonicus was obtained at levels of 15–30 g kg^?1 of dietary SPC. Feeding trials with postlarval P. japonicus showed that low levels of dietary SPC (15 g kg^?1) were more beneficial than higher levels of SPC (30 g kg^?1) or DSL (65 g kg^?1), although early postlarvae (<3 mg dry weight) presented a higher requirement for PC than later stages. Shrimp fed the 150 g kg^?1 PC-supplemented diets exhibited significantly better resistance to salinity stress than those fed a PC-deficient diet. A high level of dietary soybean lecithin (65 g kg^?1 DSL), providing 15 g kg^?1 of dietary PC, was no more effective for young postlarvae of P. japonicus than 15 g kg^?1 of purified PC alone, which suggested that the other phospholipids (mainly phosphatidylethanolamine and phosphatidylinositol) in the soybean lecithin are not required for postlarval shrimp, at least when there is already an adequate source of PC.     

Effect of l‐ascorbyl‐2‐polyphosphate supplementation on growth performance,body composition,antioxidative capacity and salinity stress tolerance of juvenile Pacific white shrimp,Litopenaeus vannamei

An 8‐week feeding trial was conducted to evaluate the effects of ascorbic acid (AsA), in the form of l ‐ascorbyl‐2‐polyphosphate (LAPP) on growth performance, body composition, antioxidative capacity and salinity stress tolerance of juvenile Pacific white shrimp, Litopenaeus vannamei. Five practical diets (46% crude protein and 7.6% lipid) supplemented with graded levels of AsA (14.64, 48.55, 84.98, 308.36 and 639.27 mg kg^?1 diet) were fed to five replicate groups of L. vannamei (mean initial wet weight 0.57 g). No significant differences were found on growth performance among all treatments. However, whole body lipid content significantly decreased with dietary AsA levels increasing. Activities of total antioxidant capacity, glutathione reductase and glutathione peroxidase were significantly affected by dietary AsA levels. Shrimp fed LAPP‐free diet had higher malondialdehyde content than those fed the diets supplemented with LAPP. Dietary AsA levels higher than 308.36 mg kg^?1 diet increased the survival of shrimps after 1, 2 and 3 h of acute salinity change. Broken‐line regression analysis on survival after 3 h of salinity stress and second‐degree polynomial regression analysis on glutathione reductase data indicated that the optimal dietary AsA requirement of L. vannamei was estimated to be 306.39, 319.75 mg kg^?1 diet respectively.     

Dietary calcium requirements of juvenile tilapia, Oreochromis niloticus × O. aureus, reared in fresh water

A feeding experiment was conducted to determine the dietary calcium (Ca) requirement for juvenile hybrid tilapia, Oreochromis niloticus × O. aureus reared in nature water. Purified diet supplemented with 0, 1, 2, 3, 4, 5, 7 and 10 g Ca kg⁻¹ diet providing of 0.6, 1.6, 2.6, 3.7, 4.7, 5.5, 7.5 and 10.7 g Ca kg⁻¹ diet, respectively, were fed to tilapia (mean initial weight: 0.52 ± 0.01 g, n = 3) for 8 weeks. Each diet was fed to three replicate groups of fish in a closed, recirculating fresh water rearing system. The rearing water contained 27.1–33.3 mg L⁻¹ Ca. The tilapia fed the diets supplemented with ≥3.7 g Ca kg⁻¹ had significantly (P < 0.05) higher weight gain, when compared with fish fed the diet with ≤1.6 g Ca kg⁻¹. Fish fed the unsupplemented control showed significantly lower weight gain when compared with the other groups (P < 0.05). Bone Ca concentration was highest in fish fed the diets with ≥4.7 g Ca kg⁻¹, intermediate in fish fed the diet with 2.6 g Ca kg⁻¹ and lowest in fish fed the control diet. Scale Ca concentration was higher in fish fed the diets with ≥3.7 g Ca kg⁻¹ than in fish fed the diets with ≤2.6 g Ca kg⁻¹. Serum alkaline phosphatase activity was 36% increased in fish fed the diets with ≥2.6 g Ca kg⁻¹ than fish fed the diets with <1.6 g Ca kg⁻¹. Analysis by broken‐line regression of weight gain, bone and scale Ca concentrations indicated that the adequate dietary Ca concentration for tilapia in water containing 27.1–33.3 mg Ca L⁻¹ was 3.5, 4.3 and 4.2 g Ca kg⁻¹ diet, respectively, supplied as Ca‐lactate.     

Dietary thiamin could improve growth performance,feed utilization and non‐specific immune response for juvenile Pacific white shrimp (Litopenaeus vannamei)

This study evaluated the effect of dietary thiamin on growth performance, feed utilization and non‐specific immune response for juvenile Pacific white shrimp, Litopenaeus vannamei. Six isonitrogenous and isolipidic practical diets were formulated with graded thiamin levels of 6.9, 32.7, 54.2, 78.1, 145.1 and 301.5 mg kg^?1 of dry diet, respectively. Each diet was randomly assigned to triplicate groups of 30 juvenile shrimp and provided four times each day to apparent satiation. Weight gain (WG) and specific growth rate (SGR) of the shrimp were significantly influenced by the dietary thiamin levels, the maximal WG and SGR occurred at 54.2 mg kg^?1 dietary thiamin level. However, with further increase in dietary thiamin level from 54.2 to 301.5 mg kg^?1, the WG and SGR significantly decreased. Shrimp fed the 54.2 mg kg^?1 thiamin diet exhibited higher feed efficiency, protein efficiency ratio and protein productive value than those fed the other diets. Dry matter and protein content in whole body were significantly affected by the dietary thiamin levels. Thiamin concentration in hepatopancreas significantly increased when the dietary thiamin level increased from 6.9 to 145.1 mg kg^?1. The total protein, glucose, triacylglycerol and cholesterol contents in hemolymph were not significantly affected by the dietary thiamin levels. Dietary thiamin had significantly influenced superoxide dismutase, catalase and lysozyme activities in hemolymph. Results of this study indicated that the optimal dietary thiamin requirements estimated using a two‐slope broken‐line model based on WG and thiamin concentration in hepatopancreas were 44.66 and 152.83 mg kg^?1, respectively.     

The effect of vitamin A supplementation in broodstock feed on reproductive performance and larval quality in Penaeus chinensis

The effect of feeding four semi‐purified diets A1, A2, A3, A4, containing different vitamin A acetate levels 0, 20, 40, 60 mg kg^?1 diet, respectively, on fecundity, egg hatching rate, larval survival rate and vitamin A content in eggs of Chinese shrimp (Penaeus chinensis) broodstock was compared with a fresh clam diet (control) in a 60‐day feeding trial. The broodstock shrimp fed the diet with 60 mg kg^?1 vitamin A acetate added exhibited significantly higher fecundity (P < 0.01). Hatching rate was highest with diet A4 (P < 0.05), whereas hatching rates were similar fed diets A1, A2, A3. Increasing levels of vitamin A in broodstock diet resulted in improvement in larval quality. The vitamin A levels in shrimp eggs from broodstock fed with diet A4 were higher compared with those from broodstock fed with diet A1, A2 (P < 0.01). The fecundity and hatching percentages were positively correlated with the vitamin A content in eggs in the present study. The results of this study showed that higher level of vitamin A in broodstock diet may have positive effects on fecundity and larval quality in P. chinensis.     

Effects of dietary vitamin E level on growth and tissue lipid peroxidation of soft-shelled turtle, Pelodiscus sinensis (Wiegmann)

A feeding trial was conducted to determine the effect of dietary vitamin E supplementation on growth, liver lipid peroxidation and liver and muscle vitamin E level of soft‐shelled turtle, Pelodiscus sinensis. Eight experimental diets analysed to contain 0–457 IU vitamin E kg^?1 were fed to juvenile soft‐shelled turtle of 4.8 g initial body weight for 12 weeks. Weight gain (WG) of the turtles fed the diet containing no vitamin E was significantly lower than those fed diets containing 83–457 IU vitamin E kg^?1 (P<0.05). Feed conversion ratio and protein efficiency ratio showed similar trends to that of WG. No significant difference (P>0.05) was found in whole‐body composition among turtles fed the different diets. Dietary vitamin E requirement using WG as the response and estimated using the broken‐line regression model is approximately 88 IU kg^?1. Liver and muscle vitamin E content increased when dietary vitamin E level increased. Ascorbate‐induced lipid peroxidation in liver tissue of turtles fed diets containing 0 and 17 IU vitamin E kg^?1 was significantly (P<0.05) greater than those fed diets containing high vitamin E (≥35 IU kg^?1).     

The effect of vitamin E on growth, survival and hepatopancreas structure of the Argentine red shrimp Pleoticus muelleri Bate (Crustacea, Penaeidea)

Two trials were conducted to evaluate the growth, survival and hepatopancreas histology of the Argentine red shrimp Pleoticus muelleri (Bate, 1888) fed different levels of vitamin E and butylated hydroxytoluene (BHT) in a semipurified diet. The diets contained 0, 100, 600 or 1500 mg vitamin E kg^?1 and 16 mg BHT kg^?1 diet (trial 1) and 0, 1250, 1500, 1750 or 2000 mg vitamin E kg^?1 diet, squid mantle and vitamin‐free diet as a control (trial 2). After 30 days (trial 1), survival ranged between 43% and 64%, and the percentage weight gain of the shrimp varied from 22% to 31% with no significant differences among treatments (P<0.05). After 40 days (trial 2), survival of shrimp fed the diet with no vitamin E and squid mantle was significantly lower (62%) than the other treatment (86–90%). Shrimp fed diets containing vitamin E from 1250 to 1750 mg kg^?1 exhibited increased weight gain (34–65%); however, a significant difference was observed for shrimp fed the diet containing 2000 mg kg^?1. Histological results yielded differences among treatments. In shrimp fed 1750 mg kg^?1 of vitamin E, the functional morphology of the organ was normal, with abundant secretion in the tubules. Signs of malnourishment such as cellular and nuclear retraction, desquamation of cells and hipertrofia, were evident in the hepatopancreas of shrimp fed the other diets. The results indicate that optimal vitamin E requirement for P. muelleri under the present experimental conditions appears to be approximately 1750 mg vitamin E kg^?1 diet.     

Growth and performance of Penaeus semisulcatus (de Haan) fed with two commercial shrimp feeds

Two feeding trials were conducted in two stages to compare growth and performance, grow‐out (1–9 g b.w.) and fattening (13–19 g b.w.), of Penaeus semisulcatus. Shrimps were fed with two commercial feeds: P. monodon feed and P. japonicus feed. Both experiments were conducted using an indoor flow‐through tank culture system. The results reveal that the growth performance of shrimp fed with P. japonicus feeds (0.91 g shrimp^?1 week^?1) for the grow‐out stage was significantly better than shrimp fed with P. monodon feeds (0.63 g shrimp^?1 week^?1). The growth performance of shrimp fed with P. monodon feed (0.56 g shrimp^?1 week^?1) for the fattening stage was significantly better than shrimp fed with P. japonicus feed (0.42 g shrimp^?1 week^?1). The feed conversion ratios of both diets for the two sizes did not differ significantly. Thus, it is recommended that P. japonicus feeds be fed to P. semisulcatus during the grow‐out stage. During the fattening stage, the better growth performance of the shrimp fed with P. monodon feed makes it a better feed. However, colour and overall acceptability of shrimp fed with P. japonicus feed were generally higher than those fed with P. monodon feed.     

Requirements of vitamin C (l-ascorbyl-2-sulphate and l-ascorbyl-2-polyphosphate) and its effects on non-specific immune responses of grouper, Epinephelus malabaricus

An 8‐week feeding trial was conducted to determine two vitamin C derivatives, l ‐ascorbyl‐2‐sulphate (C2S) and l ‐ascorbyl‐2‐polyphosphate (C2PP), to satisfy vitamin C requirement and to test their effects on the non‐specific humoral immune responses of juvenile grouper, Epinephelus malabaricus. C2S and C2PP were each supplemented at 20, 50, 80, 150, 250 and 400 mg kg^?1 diet in the semi‐purified basal diet providing of 7, 16, 28, 55, 86, 142 mg ascorbic acid (AA) equivalent of C2S kg^?1 diet and 4, 9, 15, 31, 49, 75 mg AA equivalent of C2PP kg^?1 diet, respectively. Basal diet without AA supplemented was included as a control. Each diet was fed to triplicate groups of grouper (mean initial weight: 6.69 ± 0.07 g). Fish fed diets with ≥28 mg AA equivalent of C2S or ≥4 mg AA equivalent of C2PP kg^?1 had significantly (P < 0.05) greater weight gain (WG) than fish fed the unsupplemented control diet. Liver AA concentrations were higher in fish fed diets with ≥16 mg AA equivalent of C2S or ≥9 mg AA equivalent of C2PP kg^?1 than fish fed the control diet. Alternative pathway of complement activation (ACP) was higher in fish fed diets with ≥55 mg AA equivalent of C2S or ≥15 mg AA equivalent of C2PP kg^?1 than fish fed the control diet. Lysozyme activity was higher in fish fed ≥86 mg AA equivalent of C2S or ≥15 mg AA equivalent of C2PP kg^?1 than fish fed the control diet. Analysis by broken‐line regression of WG indicated that the adequate dietary vitamin C concentration from each vitamin C derivative in growing grouper is 46.2 mg AA equivalent of C2S kg^?1 diet and 17.8 mg AA equivalent of C2PP kg^?1 diet, and it also indicated that C2S is approximately 39% as effective as C2PP in meeting the vitamin C requirement for grouper. The data suggest that both C2S and C2PP supplementation support non‐specific immune responses of grouper.     

Partial replacement of fish meal with peanut meal in practical diets for the Pacific white shrimp,Litopenaeus vannamei

In this study, we replaced fish meal with peanut meal (PM) in isonitrogenous and isolipidic diets for Pacific white shrimp at inclusion levels of 0, 70, 140, 210, 280 and 350 g kg^?1. The diets were hand‐fed to three independent groups of shrimp three times a day over a 6‐week period. Shrimp fed PM diets at a level of 280 g kg^?1 or higher had lower per cent weight gain compared with those fed the basal diet, whereas shrimp fed PM diets at 140 g kg^?1 or higher had a lower feed utilization and protein efficiency ratio compared with shrimp fed the basal diet. The feeding rate in shrimp fed PM diets at 350 g kg^?1 and the survival and protease activity in shrimp fed PM diets at 210 g kg^?1 or higher were lower than that in shrimp fed the basal diet. Diets containing 280 g kg^?1 or higher of PM caused an increase in the whole‐body moisture content of the shrimp, but decreased whole‐body protein and ash contents compared with the basal diet. Nutrient digestibility was lower or tended to be lower in shrimp fed a PM diet compared with those fed the basal diet. The activities of peroxidase and acid and alkaline phosphatases in plasma decreased with increasing levels of PM inclusion up to 210 g kg^?1. Superoxide dismutase activity decreased at dietary PM levels of 280 g kg^?1 or higher. Aflatoxin B₁ residue in the muscle was not affected by any of the treatments and remained low. The data suggest that up to 140 g kg^?1 of PM could be included in practical diets for Pacific white shrimp.