Effects of dietary lipids on body composition and liver function in juvenile red drum, Sciaenops ocellatus

This study was conducted to evaluate the effects of different concentrations of dietary lipids on body composition and liver function in juvenile red drum, Sciaenops ocellatus. Diets were formulated to contain 40% crude protein from solvent-extracted menhaden fish meal and 0, 7, 14 or 21% lipid from menhaden fish oil. The basal diet, without supplemental fish oil, contained lipid at 0.4% of dry weight. The diets were fed to groups of 25 juvenile red drum initially averaging 7.3 ± 0.18 g fish^–1 in a recirculating culture system for 8 weeks and weight gain was recorded. After an additional 8 weeks, 16 fish from each treatment were sacrificed and the following measurements were recorded: hepatosomatic index (HSI), intraperitoneal fat (IPF) ratio, and liver -tocopherol, malondialdehyde (MDA) formation, and cytochrome P-4501A activity (measured as 7-ethoxyresorufin O-deethylase (EROD) activity). The activity of alanine and aspartate aminotransferases and concentrations of -tocopherol also were measured in plasma.Weight gain was significantly (p<0.05) affected by dietary lipid concentration, with values ranging from 361% of initial weight for fish fed the basal diet to 527% of initial weight for fish fed the diet containing 7% lipid. The HSI and IPF ratio values also were significantly affected by lipid with the lowest values recorded for fish fed the basal diet and the highest values observed in fish fed the diet containing 21% lipid. Increasing dietary lipid significantly increased oxidative stress as reflected in reduced -tocopherol in liver and plasma and increased MDA formation in the liver, although no overt pathological signs were observed. These findings suggest that lipid concentrations between 7 and 14%, when the diet contains 60 IU vitamin E kg^–1, are likely to limit oxidative stress and result in normal physiological responses of red drum.     

Long-term effects and interactions of dietary vitamins C and E on growth and reproduction of yellow perch, Perca flavescens

This study was conducted to examine the effects of dietary vitamin C and/or E and their interaction on growth and reproductive performance in yellow perch. Yellow perch juveniles were divided into four treatments with triplicate groups and fed with one of four semi-purified diets for 32 weeks. The experimental diets were formulated to contain no or high vitamin E levels (160 mg/kg) without or with vitamin C supplementation (250 mg/kg) designated as diets −C−E, −C+E, +C−E, or +C+E, respectively. The growth rates and survival of yellow perch fed with +C−E and +C+E diets were significantly higher than the fish fed with −C−E diet. Total- and dehydro-ascorbate concentrations in liver and testis increased in response to its dietary supplementation. The -tocopherol concentration in sperm was significantly affected by dietary supplementation of vitamin C. Gonadosomatic index of males was lower in the fish fed with −C−E diet compared to that of fish fed with other diets. Hatching rates of embryos obtained from testing sperm viability was significantly improved in fish fed with the diets sufficient in vitamin C (82±7%) compared to the fish fed with the −C−E diet (59±7). This study indicates that supplementation of dietary vitamin C and E increase growth rate, and semen quality can be improved by dietary vitamin C supplementation within one maturation cycle, and vitamin C may spare sperm vitamin E depending on vitamin E stores in tissues.     

Relationship between biochemical constituents of fish semen and fertility: the effect of short-term storage

Spermatozoa and seminal plasma obtained from rainbow trout and whitefish were analyzed in respect to their aspartate aminotransferase (AspAT) and alkaline phosphatase activities. In particular, the experiments characterized AspAT optimum pH, optimization of assay conditions and action of coenzyme, pyridoxal 5-phosphate (vitamin B₆). The effect of short-term semen storage at 0°C on biochemical indicators and fertilization rate was examined in both species. The concentrations of reduced and oxidized ascorbic acid in seminal plasma of both species were several folds higher than in spermatozoa and blood plasma of fish. Highly significant correlations were found for both species between AspAT activity (sperm or seminal plasma) and fertilization rate (% of eyed-stage or hatched embryos). For rainbow trout, highly significant correlations were found between sperm concentration, motility and fertilization rate. These results suggest that several biochemical indicators of seminal plasma can be used as measures of sperm quality of fish. Some common biochemical parameters for fish and mammal's semen provide evidence for using fish sperm as a model in biomedical research.     

Effect of Source and Dietary Concentration of Ascorbic Acid on Tissue Concentrations of Ascorbic Acid in Channel Catfish

Semipurified diets containing either no ascorbic acid or supplemental amounts of 11, 22, 44 and 132 mg/kg from Gascorbic acid (AA), L-ascorbyl-2-monophosphate (AAP) or L-ascorbyl-2-sulfate (AAS) were fed to channel catfish fingerlings (13 ± 2.1 g average initial weight) in aquaria. After a feeding period of 14 wk, weight gain was measured and ascorbic acid content of liver and anterior kidney of the fish was determined. Growth was normal for fish fed all dietary levels of AA and AAP, but lower in fish fed the control and diets supplemented with all levels of AAS; however, growth improved as the concentration of AAS increased. Liver and kidney ascorbic acid increased with level of dietary supplementation in fish fed AA and AAP but only traces or no detectable levels were found in the tissues of fish fed AAS or the controls. Liver and kidney levels of ascorbic acid were significantly higher in fish fed AAP than in fish fed corresponding levels of ascorbic acid from AA. Regression of liver ascorbic acid content on diet concentration indicated that the potency of AAP for maintaining liver storage of ascorbic acid at a minimum acceptable level is 1.74 times higher than that of AA on an ascorbic acid equivalent basis. These results demonstrate that AAP and AA have similar vitamin activity for growth in channel catfish, but AAP is markedly more effective for maintaining tissue levels of ascorbic acid, and that AAS has limited vitamin activity for growth and its contribution to the tissue ascorbic acid pool is negligible.     

Dietary ascorbic acid requirement for growth of striped catfish,Pangasianodon hypophthalmus (Sauvage, 1878) juveniles

A sixty‐day feeding trial was conducted to determine the ascorbic acid (AA) requirement for growth of striped catfish, Pangasianodon hypophthalmus juveniles. Seven iso‐nitrogenous and iso‐energetic (370 g protein per kg and 19.6 MJ/kg) purified diets were prepared with different levels of ascorbic acid such as control (0), T₁ (17.5), T₂ (35), T₃ (70), T₄ (175), T₅ (350) and T₆ (700) mg ascorbic acid (L‐ascorbyl‐2‐polyphosphate) equivalent per kg diet. Fish with a mean body weight of 3.2–3.4 g were stocked (fifteen fish per tank) in triplicates following a completely randomized design. Each group was fed to satiation twice a day for 60 days. Significant differences were observed in growth, survival, body composition and metabolic enzymes activities with different dietary ascorbic acid levels. Maximum weight gain, specific growth rate (SGR) and protein efficiency ratio (PER) were found in fishes fed with 35 mg AA per kg diet, supported by best feed conversion. Fish fed a diet containing vitamin C had the highest activities of aspartate aminotransferase (AST), alanine aminotransferase (ALT) and alkaline phosphatase (ALP) compared to those fed with vitamin C‐depleted diets. In this study, based on using broken‐line regression analysis, the dietary vitamin C requirement for growth of P. hypophthalmus juveniles was estimated to be in the range of 46–76 mg AA per kg, depending on the criterion used, growth and liver storage. Our results will be helpful for the formulation of cost‐effective ascorbic acid incorporated diets for striped catfish, P. hypophthalmus.     

The effect of varying forms of dietary ascorbic acid on the nutrition of juvenile tilapias (Oreochromis niloticus)

An 8-week growth study was conducted to evaluate the utilisation of L-ascorbic acid (AA), the sodium salt of L-ascorbic acid (NaAA), glyceride coated L-ascorbic acid (GCAA), the barium salt of L-ascorbic acid 2-sulphate (AA2S) and ascorbyl palmitate (AP) in diets for Oreochromis niloticus. All five forms were added to the basal diet, containing no ascorbic acid (AAF) on an equimolar basis to supply 125 mg ascorbic acid/100 g of dry diet. In terms of growth, feed conversion and protein utilisation diets containing all forms of ascorbic acid performed well. Fish fed AAF performed poorly and showed clinical signs of ascorbic acid deficiency such as haemorrhage, caudal fin erosion, exophthalmia, and 7% exhibited spinal deformity. Fish fed diet AAF also exhibited depressed haematocrit, haemoglobin, hepatosomatic index and muscle and liver glycogen compared with fish fed diets containing the vitamin C forms. Total ascorbate concentrations in 10 tissues were lowest in fish fed diet AAF and lower in fish fed AA2S than for the other ascorbic acid forms. When supplied in semipurified diets on an equimolar basis the five forms of ascorbic acid evaluated supported similar performance and alleviated signs of deficiency.     

Enhancement of Stress Resistance of the Guppy Poecilia reticulata through Feeding with Vitamin C Supplement

This study investigated the use of vitamin C supplement in formulated diets and live Artemia juveniles to enhance the stress resistance of the guppy Poecilia reticulata . To evaluate the stress resistance, fish were subjected to osmotic shock in pre-aerated water containing 35 ppt sodium chloride. Ascorbyl acid-polyphosphate and ascorbyl palmitate were used as vitamin C sources for formulated diets and live Artemia juveniles, respectively. Results showed that guppies fed moist formulated diets supplemented with ascorbic acid at 1,000 mg/kg or 2,000 mg/kg diet displayed significantly higher levels of stress resistance than fish fed control formulated diet for 13 d. The stress resistance of fish fed a lower dose (200 mg/kg diet), however, did not differ significantly from that of the control. On the other hand, the stress resistance of guppies fed Artemia juveniles bio-encapsulated with 10% or 20% ascorbyl palmitate did not show significant difference from that of fish fed control Artemia after 20 d. The stress resistance of these three groups of Artemia- fed fish, however, was significantly higher than that of fish fed the control formulated diet. Biochemical analyses showed that raising the ascorbic acid level in feeds resulted in a concomitant increase in the incorporated ascorbic acid level in the whole-body tissue of the guppy. The increased stress resistance of the guppy fed a vitamin C supplemented diet has also been demonstrated in four commercial farms. The potential application of the improved stress resistance in the ornamental fish industry was discussed.     

Effect of Dietary pH Adjustment on the Utilization of Supplemental Methionine and Lysine by Juvenile Common Carp,Cyprinus carpio

An 8‐wk feeding trial was conducted to compare the effect of dietary pH on the utilization of crystalline amino acid (CAA, 0.2% dl ‐methionine and 0.4% l ‐lysine·HCl) by juvenile common carp, Cyprinus carpio. A basal diet (diet C) with protein derived mostly from fish meal and soybean meal was supplemented with CAA without pH adjustment (diet CAA, pH 6.2) and with pH adjusted to 7.0 and 8.0 (diets CAA pH 7.0, CAA pH 8.0, respectively). Supplementation of CAA, regardless of dietary pH adjustment, significantly increased the feed intake and weight gain, and the latter was significantly higher in fish fed diets CAA pH 7.0 or CAA pH 8.0 compared to fish fed diet CAA. The intestinal protease activity was significantly higher in fish fed diets CAA pH 7.0 or CAA pH 8.0 compared to fish fed diet CAA. Apparent digestibility of dry matter and crude protein in diets CAA pH 7.0 and CAA pH 8.0 were significantly higher than those in diet C. Dietary supplementation of CAA generally decreased the plasma aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities, but markedly increased the hepatic AST and ALT activities. Compared to fish fed diet CAA, fish fed diets CAA pH 7.0 or CAA pH 8.0 showed higher hepatic AST activity but slightly lower plasma ammonia level. These results indicate that adjusting the pH of CAA‐supplemented diets to neutral or slightly alkaline resulted in improving the CAA utilization by common carp.     

Responses of Juvenile Golden Shiner Notemigonus crysoleucas Fed Semipurified or Practical Diets With or Without Supplemental Ascorbic Acid

A 12-wk feeding trial was conducted in a flow-through system to determine whether juvenile golden shiner Notemigonus crysoleucas have a dietary requirement for ascorbic acid. Triplicate groups of 30 fish each weighing 0.44 g initially were fed semi-purified (casein) diets supplemented with 0 or 250 mg ascorbic acid/kg, or practical (fish meal) diets supplemented with 0 or 250 mg ascorbic acid/kg. The form of ascorbic acid used was L-ascorbyl-2-polyphosphate. Survival was higher in fish fed the semi-purified diet with 250 mg ascorbic acid/kg than in those fed the unsupplemented semi-purified diet, while weight gain did not differ between treatments. Weight gain was higher in fish fed the practical (fish meal) diet supplemented with 250 mg ascorbic acid/kg than in those fed the unsupplemented practical diet, while survival did not differ between treatments. No other signs of ascorbic acid deficiency were observed, but fish fed the casein diets had skin and fin erosion indicative of a possible bacterial infection. Whole-body concentrations of ascorbic acid (total, reduced, and percent of reduced ascorbic acid) were higher in fish fed semi-purified or practical diets supplemented with 250 mg ascorbic acid/kg than in fish fed unsupplemented diets. Golden shiners appear to require a dietary source of ascorbic acid for growth or survival, depending on experimental conditions. The two main differences in the study were in diet composition (semi-purified versus practical diets) and apparent health status of fish fed the different diet types. Additional studies are needed to define requirements further.     

Effects of dietary amylose/amylopectin ratio on growth performance,feed utilization,digestive enzymes,and postprandial metabolic responses in juvenile obscure puffer Takifugu obscurus

The effect of dietary amylose/amylopectin (AM/AP) ratio on growth, feed utilization, digestive enzyme activities, plasma parameters, and postprandial blood glucose responses was evaluated in juvenile obscure puffer, Takifugu obscurus. Five isonitrogenous (430 g kg^?1 crude protein) and isolipidic (90 g kg^?1 crude lipid) diets containing an equal starch level (250 g kg^?1 starch) with different AM/AP ratio diets of 0/25, 3/22, 6/19, 9/16 and 12/13 were formulated. Each experimental diet was fed to triplicate groups (25 fish per tank), twice daily during a period of 60 days. After the growth trial, a postprandial blood response test was carried out. Fish fed diet 6/19 showed best growth, feed efficiency and protein efficiency ratio. Hepatosomatic index, plasma total cholesterol concentration, liver glycogen and lipid content, and gluconokinase, pyruvate kinase and fructose-1,6-bisphosphatase activities were lower in fish fed highest AM/AP diet (12/13) than in fish fed the low-amylose diets. Activities of liver and intestinal trypsin in fish fed diet 3/22 and diet 6/19 were higher than in fish fed diet 9/16 and diet 12/13. Activities of liver and intestinal amylase and intestinal lipase, and starch digestibility were negatively correlated with dietary AM/AP ratio. Fish fed diet 3/22 and diet 6/19 showed higher plasma total amino acid concentration than fish fed the other diets, while plasma urea nitrogen concentration and activities of alanine aminotransferase and aspartate aminotransferase showed the opposite trend. Equal values were found for viscerosomatic index and condition factor, whole body and muscle composition, plasma high-density and low-density lipoprotein cholesterol concentrations, and activities of lipase and hexokinase and glucose-6-phosphatase in liver. Postprandial plasma glucose and triglyceride peak value of fish fed diet 12/13 were lower than in fish fed the low-amylose diets, and the peak time of plasma glucose was later than in fish fed the other diets. Plasma glucose and triglyceride concentrations showed a significant difference at 2 and 4 h after a meal and varied between dietary treatments. According to regression analysis of weight gain against dietary AM/AP ratio, the optimum dietary AM/AP ratio for maximum growth of obscure puffer was 0.25. The present result indicates that dietary AM/AP ratio could affect growth performance and feed utilization, some plasma parameters, digestive enzyme as well as hepatic glucose metabolic enzyme activities in juvenile obscure puffer.     

Optimum Dietary Level of L-ascorbic Acid for Japanese Eel, Anguilla japonica

A feeding experiment was conducted to determine the optimum dietary level of ascorbic acid (AsA) for Japanese eel juveniles using L-ascorbic acid Ca based on growth, AsA content in tissues, hematology, and bactericidal activity of serum with Escherichia coli . Test diets with six levels of AsA (3, 10, 27,126, 645, and 3,135-mg/kg diet) as Ca ascorbate were fed to juvenile Japanese eels (11.0 ± 0.2 g) once a day for 8 wk. High survival rates (> 80%) were observed among all dietary treatment groups. The specific growth rates of the fish fed diets containing 3 and 10-mg AsA/kg were significantly (P < 0.05) lower than those of other groups. Liver and brain AsA contents of the fish fed diets containing 3, 10, and 27-mg AsA/kg were significantly (P < 0.05) lower than those of the fish fed diets containing 645 and 3,135-mg AsA/kg. Hemoglobin content tended to be higher in the fish fed diets containing 645 and 3,135-mg AsA/kg than those of the fish fed other diets. Hematocrit value and total serum protein content of the fish fed diets containing 645 and 3135 mg AsA/kg were significantly (P < 0.05) higher than those of the other groups. The fish fed diets containing more than 27-mg AsAlkg showed a higher bactericidal activity of serum than the fish fed the diets containing 3-mg and 10-mg AsA/kg. The optimum dietary level of AsA for the Japanese eel juveniles growth was estimated to be more than 27-mg AsA/kg. Furthermore, the inclusion of 645-mg AsA/kg or more also increased the hematocrit, hemoglobin, total serum protein value, and liver and brain vitamin C concentrations.     

Dietary vitamin E requirement of the red drum Sciaenops ocellatus

A 12-week feeding trial was conducted to establish the minimum dietary vitamin E requirement of juvenile red drum by broken-line regression analysis. The semi-purified basal diet was supplemented with 10, 20, 30, 40, 60 or 80 IU vitamin E kg⁻¹ as all-rac -α-tocopheryl acetate. Juvenile red drum were conditioned by feeding the basal diet for 8 weeks prior to the feeding trial to reduce whole-body vitamin E levels. Then, fish initially averaging 12.2 ± 0.4 g fish⁻¹ (mean ± SD) were fed the experimental diets at a rate approaching apparent satiation for 12 weeks. Weight gain and feed efficiency responses of fish fed diets were significantly ( P  < 0.01) altered by the level of vitamin E supplementation but not strictly in a dose-dependent manner. Vitamin E concentrations in liver and plasma also were significantly ( P  < 0.001) influenced by dietary vitamin E level. Plasma ascorbic acid in fish fed the basal diet tended ( P  = 0.066) to be lower than in fish fed diets containing the various levels of vitamin E. In addition, fish fed the basal diet showed edema in the heart, while fish fed all other diets were normal. Fish fed 60 or 80 IU all-rac -α-tocopheryl acetate kg⁻¹ diet had significantly higher respiratory burst of head kidney macrophages than fish fed all other diets, although dietary effects on hematocrit and neutrophil oxidative radical production were not significant. The minimum dietary vitamin E requirement of juvenile red drum was established based on broken-line regression of liver thiobarbituric acid reactive substances to be 31 mg all-rac -α-tocopheryl acetate kg⁻¹ diet.     

Gastrointestinal and hepatic enzyme activities in juvenile silvery-black porgy (<Emphasis Type="Italic">Sparidentex hasta</Emphasis>) fed essential amino acid-deficient diets

As amino acids (AAs) are vital molecules in the metabolism of all living organisms and are the building blocks of enzymes, a 6-week feeding trial was conducted for determining the influence of dietary essential amino acid (EAA) deficiencies on pancreatic, plasma, and hepatic enzyme activities in silvery-black porgy (initial weight 4.7?±?0.01 g) juveniles. Eleven isoproteic (ca. 47%) and isoenergetic (ca. 20.5 MJ kg^?1) diets were formulated including a control diet, in which 60% of dietary nitrogen were provided by intact protein (fish meal, gelatin, and wheat meal) and 40% by crystalline AA. The other 10 diets were formulated by 40% reduction in each EAA from the control diet. At the end of the experiment, fish fed with threonine-deficient diet showed the lowest survival rate (P?<?0.05), whereas growth performance decreased in fish fed all EAA-deficient diets, although the reduction in body growth varied depending on the EAA considered. Pancreatic enzymes (trypsin, lipase, α-amylase, and carboxypeptidase A) activities significantly decreased in fish fed the EAA-deficient diets in comparison with fish fed the control diet (P?<?0.05). Fish fed with the arginine-deficient diet had the highest plasma and liver alanine aminotransferase, aspartate aminotransferase, and alkaline phosphatase levels (P?<?0.05). Plasma and liver lactate dehydrogenase and superoxide dismutase showed the highest and lowest values, respectively, in fish fed the arginine and lysine-deficient diets (P?<?0.05). Plasma metabolites were significantly affected by dietary EAA deficiencies (P?<?0.05). The results of this study suggesting dietary EAA deficiencies led to reduction in growth performance as well as pancreatic and liver malfunction. Furthermore, arginine and lysine are the most limited EAA for digestive enzyme activities and liver health in silvery-black porgy.     

Effects of dietary vitamin C on growth and parr-smolt transformation in Atlantic salmon, Salmo salar L.

Atlantic salmon (Salmo salar) parr were fed fish meal based pelleted diets supplemented with graded levels of ascorbate-2-monophosphate (AP), equivalent to 0, 20, 60 and 1000 mg ascorbic acid (AA) kg”¹ throughout smoltification on a continuous light regime from February to June. No differences were observed in growth rate and body length distribution between the dietary regimes. The condition factor and the hepatosomatic index were somewhat elevated in fish fed no vitamin C throughout the smoltification, which can reflect changes in lipid metabolism in fish with suboptimal vitamin C nutrition. Sea water challenge tests (exposure to sea water with salinity of 34 gL^?1 and ambient temperature for 24 h) performed monthly did not reveal differences attributed to the vitamin C status, as measured by mortality, serum chloride and cortisol concentrations, haematological parameters and liver and head kidney ascorbate concentrations after 24 h. Elevated serum cortisol concentrations most probably reflected stress in the challenge tests, and some lower concentrations in fish fed high vitamin C levels may indicate a certain stress-ameliorating effect. The present results do not, however, support the anticipation of increased requirement of dietary vitamin C above the minimum requirement during smoltification in Atlantic salmon.     

Dietary Vitamin C Requirement of Hybrid Striped Bass Morone chrysops♀× M. saxatilis ♂

A feeding trial was conducted to determine the dietary vitamin C requirement of juvenile hybrid striped bass Morone chrysops × M. saxatilis . Fish were fed a semi-purified basal diet with 40% crude protein and an energy to protein ratio of 8 kcal/g for a conditioning period of 2 wk. This diet which was not supplemented with vitamin C contained approximately 6-mg vitamin C/kg. Following conditioning, fish (approximately 0.55 g initial weight) were stocked as groups of 20 in 38-L aquaria and fed the basal diet and experimental diets supplemented with 10, 20, 30, 45, 60, 75, or 150-mg vitamin C/kg as ascorbate polyphosphate for a period of 10 wk. Fish fed the basal diet and the diet supplemented with 10-mg vitamin C/kg exhibited signs of vitamin C deficiency including suppressed weight gain, reduced plasma and liver ascorbic acid levels, and abnormalities in isthmus cartilage formation. Plasma and liver ascorbic acid levels generally reflected dietary supplementation with the lowest levels occurring in fish fed the basal diet and higher levels in fish fed the supplemented diets. The minimum dietary requirement (±SE) based on non-linear least squares regression analysis of weight gain was 22 (±6) mg vitamin C/kg diet.     

Inclusion of <Emphasis Type="Italic">Pediococcus acidilactici</Emphasis> as probiotic candidate in diets for beluga (<Emphasis Type="Italic">Huso huso</Emphasis>) modifies biochemical parameters and improves immune functions

Administration of probiotic candidates in fish has generally been shown as a useful strategy to improve growth performance, survival, digestive enzyme activity, and gut microbiota. Unfortunately, the sero-immunological responses of different fish to different probiotic candidates are poorly understood. The present study assessed the effect of Pediococcus acidilactici as a probiotic on the biochemical and immunological parameters of beluga. Fish (248.32?±?10.21 g) were fed a control diet (without P. acidilactici( and three different doses of P. acidilactici-supplemented diets (10⁷, 10⁸, and 10⁹ CFUg^?1 diets) for 8 weeks. On week 8, blood and serum were sampled. Dose-dependent increase of immunological parameters (respiratory burst activity, lysozyme content, serum antibacterial activity, and total immunoglobulin) and biochemical parameters (total protein and albumin levels) was observed. However, alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were significantly increased in the juvenile beluga fed by 10⁹ CFUg^?1 P. acidilactici-supplemented diet compared to the other groups. Based on the results of this evaluation, it is reasonable to conclude that the inclusion of P. acidilactici as probiotic in diets for juvenile beluga improves the sero-immunological parameters of the fish and should be considered by farmers as a strategy to improve fish health.     

Effect of ascorbic acid supplement in vitro onrainbow trout sperm viability

We evaluated motility and fertilizing ability of rainbow trout Oncorhynchus mykiss semen obtained from fish fed diets without ascorbic acid and a diet supplemented with 870 mg kg^{minus 1} of ascorbyl monophosphate. Semen was stored in vitro on ice (0 °C) during 14 days. The spermatozoa from the supplemented group had the highest motility and lowest decline in fertilizing ability after storage. Lack of a positive effect of exogenous vitamin C on semen in fish deficient in ascorbic acid (milt was supplemented with 50 mg l^–1 of ascorbic acid) suggests that the positive effect of ascorbic acid on semen quality is related to its long-term effects during spermatogenesis.     

Effects of dietary Biogen and sodium butyrate on hematological parameters,immune response,and histological characteristics of Nile tilapia (<Emphasis Type="Italic">Oreochromis niloticus</Emphasis>) fingerlings

The present study was carried out to evaluate the use of Biogen and sodium butyrate (SB) as feed additives in the diet of Nile tilapia (Oreochromis niloticus) fingerlings, in two parallel experiments. Biogen was incorporated in isonitrogenous (35% crude protein) and isocaloric (19 MJ kg^?1) diets at four levels (0.0 (control), 0.5, 1.0, and 2.0%), while SB was included at five levels (0.0 (control), 0.5, 1.0, 2.0, or 3.0%). The diets were fed to fingerling Nile tilapia (10.5 ± 0.5 g) at a daily rate of 4% of their body weight, three times a day, for 60 days. Except the lymphocytes and monocyte numbers in fish fed SB, hematological parameters, including red blood cell (RBC) hematocrit (Ht), hemoglobin (Hb), and white blood cells (WBC) were not significantly (P > 0.05) affected by dietary Biogen and SB. The lymphocytes number in Nile tilapia fed on SB increased with increasing SB up to 2% level, and decreased afterwards. Monocyte numbers showed irregular patterns. The activities of serum enzymes alanine aminotransferase (ALT) and aspartate aminotransferase (AST) of fish fed diets containing Biogen or SB were not significantly affected by dietary treatments (P > 0.05). No structural differences of tilapia liver were detected between all Biogen treatments and sodium butyrate concentrations up to 1% with control. At concentrations of 2 and 3% sodium butyrate, liver steatosis increased leading to shrinked acentric nuclei. At a concentration of 2% Biogen, some glomerulus cells had fading cytoplasm. Concerning fish fed SB diets, the structure of kidney was the same as in control except at concentration of 3% SB, where the septum between cells disappeared. No changes in gill structure were noticed at all concentrations of Biogen and SB.     

饲料中不同维生素A含量对花鲈生长和血清生化指标的影响

以酪蛋白和明胶为蛋白源,鱼油和豆油为脂肪源,糊精为糖源并添加氨基酸混合物配制精制基础饲料,通过向基础饲料中添加维生素A醋酸酯使饲料中的维生素A含量达到0、1 000、2 000、4 000、8 000和16 000 IU/kg(实测含量为245、1 005、1 835、3 781、7 583和15 273 IU/kg),配制出6种等氮等能的实验饲料(饲料1～6).以花鲈为实验对象,在室内流水系统中进行为期9周的生长实验,探讨精制饲料中不同维生素A含量对花鲈生长和血清学生化指标的影响.结果表明:摄食不添加维生素A组(饲料1)饲料的花鲈在养殖后期表现出较高的死亡率,并出现眼球浮肿、膨胀、鳍基充血以及鳃盖扭曲等维生素A缺乏症,而在其他维生素A添加组(饲料2～6)并未出现类似症状.体成分分析表明:饲料中不同维生素A含量会显著增加花鲈体脂肪含量,但对蛋白质和水分的含量没有显著影响.对花鲈血清指标分析表明:饲料添加维生素A含量会显著增加花鲈血清碱性磷酸酶(AKP)、甘油三酯(TG)和胆固醇(TC)含量,但显著降低丙氨酸氨基转移酶(ALT)和天冬氨酸氨基转移酶(AST)活力.采用折线模型,当以增重率为评价指标时,花鲈对饲料中维生素A的需求量为1 934.8 IU/kg;当以肝脏维生素A含量为评价指标时,花鲈对饲料中维生素A的需求量为3 546.6 IU/kg.     

Effects of lipoic acid on growth and biochemical responses of common carp fed with carbohydrate diets

Lipoic acid (LA) is an antioxidant that also favors glucose uptake in mammals. Until now, there are no studies evaluating the potential effect of this molecule on glycemic control in fish. It was evaluated LA effects on glucose uptake in common carp Cyprinus carpio fed with carbohydrate diets from two carbohydrate sources: glucose (GLU) and starch (STA), and supplemented or not with LA, being the diets: +GLU/?LA (GLU); +GLU/+LA (GLU + LA); +STA/?LA (STA); and +STA/+LA (STA + LA). Carp juveniles (6.5 ± 0.1 g) were fed with each diet ad libitum 4 times a day, during 68 days. Muscle glycogen concentration was higher (p < 0.05) in GLU and GLU + LA than in STA and STA + LA groups. On fish fed with starch, muscle cholesterol and triglyceride concentrations were higher (p < 0.05) in fish fed diets supplemented with LA. Muscle protein levels were higher in fish fed with LA, independent of the diet carbohydrate source. Lipid peroxidation was significantly reduced (p < 0.05) in fish muscle on fish fed the STA + LA diets when compared with the STA diet. Our findings indicate that LA modulates lipid, proteins and carbohydrate metabolism together with the well-known antioxidant effect. Also, LA showed to enhance starch utilization taking into account muscle cholesterol and triglyceride levels.