Dietary supplementation of fermented lemon peel enhances lysozyme activity and susceptibility to Photobacterium damselae for orange-spotted grouper, Epinephelus coioides.

The waste recycling of lemon peel, as a functional feed additive in aquafeed was evaluated by estimating the effects of fermented lemon peel (FLP) supplementation in diet on growth performance, innate immune responses, and susceptibility to Photobacterium damselae of grouper, Epinephelus coioides. A basal diet was added FLP at 0%, 1%, 3%, and 5%. Four tested diets were each fed to juvenile grouper (initial weight: 15.89 ± 0.10 g, triplicate groups) in a recirculation rearing system for eight weeks. Fish fed diets with 0%-3% FLP exhibited higher (p < 0.05) final weight, weight gain, and feed efficiency than fish fed the 5% FLP-diet. After challenge test, fish fed the 3% FLP-diet appeared the lowest mortality, followed by fish fed the 1% FLP-diet, and lowest in fish fed 0% and 5% FLP-diets. Plasma lysozyme activities were higher in fish fed diets with FLP than in fish fed the FLP-free control diet before challenge test. After challenge, fish fed diets with 1% and 3% FLP showed highest lysozyme activities, followed by fish fed the diet with 5% FLP, and lowest in fish fed the control diet. Hepatic malondialdehyde content was higher in fish fed the control diet than in fish fed diets with 1%-3% FLP. Results found that diets supplemented with 1%-3% fermented lemon peel can enhance lysozyme activity and resistance to pathogen P. damselae of grouper.

Molecular identification of an androgen receptor and the influence of long-term aggressive interaction on hypothalamic genes expression in black rockfish (Sebastes schlegelii).

This study aims to explore the mechanism on how aggressive interaction alters reproductive physiology by testing whether aggressive interaction can activate the reproductive neuroendocrine function via the hypothalamus-pituitary-gonadal (HPG) axis in black rockfish (Sebastes schlegelii). The expressions of the androgen receptor gene (ar) and gonadotropin-releasing hormone genes (gnrhs), the concentration of plasma androgens, and GSI (the ratio of testes mass to body mass) were compared between the interaction group (dominant males or subordinate males) and the isolation group in male black rockfish after 3 weeks. A full-length cDNA encoding an androgen receptor (AR) of 766 amino acids was isolated. Transcripts encoding this AR were detected at a high relative abundance in the liver, kidney, testis, ovary, muscle, and intestine tissue. Further evaluation of brain genes transcripts abundance revealed that the mRNA levels of gnrh I and ar genes were significantly different between the interaction group and the isolation group in the hypothalamus. However, no significant difference was detected in testosterone, 11-keto-testosterone, and GSI between these two groups. This study indicates that a long-term aggressive interaction affect the expression of hypothalamic gnrh I and ar but may not change the physiological function of the HPG axis in an all-male condition.

Comprehensive physiological and transcriptomic analysis revealing the responses of hybrid grouper (Epinephelus fuscoguttatus♀ × E. lanceolatus♂) to the replacement of fish meal with soy protein concentrate.

Plant proteins are suitable and alternative to fish meals (FMs), with less cost compared with that of all other types of fish feeds. In recent years, soy protein concentrate (SPC) has emerged as a cost-effective alternative to FM; however, little is known regarding the effects of dietary SPC on general fish physiology and well-being. This study aimed to perform comprehensive physiological and transcriptomic analysis for testing the applicability of SPC as fish feeds in hybrid grouper (Epinephelus fuscoguttatus♀ נE. lanceolatus♂) [SPC replaced 0% (CK), 30% (SPC30), and 75% (SPC75) of FM protein]. Generally, SPC30 promoted fish survival and had less effects on the phenotype, while SPC75 reduced fish survival, promoted inflammation, and regulated multiple physiological responses. Thousands of differentially expressed genes (DEGs) by SPC were identified in the intestine, liver, and muscle, which were enriched in biological regulation, cellular process, metabolic process, single-organism process, cell, cell part, membrane, binding, and catalytic activity based on RNA-seq. Notably, some DEGs involved in amino acid and lipid metabolism in the digestive system highlighted the modulatory effect of SPC on these metabolic processes, consistent with the physiological responses including enzyme activities. The enriched aspects of these predominant DEGs might be directly related to the different effects of SPC30 and SPC75 on fish growth, digestibility, and underlying enzyme activities and histology. In conclusion, the comprehensive physiological and transcriptomic comparative analysis of CK, SPC30, and SPC75 was also effective in testing the applicability of SPC as fish feeds and in designing a proper diet with the best impact on the growth performance and health of fish in hybrid grouper.

Effects of dietary exogenous xylanase supplementation on growth performance, intestinal health, and carbohydrate metabolism of juvenile large yellow croaker, Larimichthys crocea.

An 8-week feeding trial was conducted to evaluate the effects of dietary xylanase supplementation on growth performance, digestive enzyme activity, intestinal morphology parameter, intestinal microbiome diversity, and carbohydrate metabolism for juvenile large yellow croaker (Larimichthys crocea). Four levels of xylanase were added to basal diets (0, 600, 1200, and 1800 U kg-1). The results indicated that fish fed the 1200 U kg-1 xylanase diet had higher weight gain than those fed the 0 and 600 U kg-1 xylanase diet. The highest intestinal folds and microvillous height were observed at fish fed the 1200 U kg-1 xylanase diet. High-throughput sequencing revealed that the majority of reads derived from the large yellow croaker digesta belonged to members of Proteobacteria followed by Chloroflex, Bacteroidetes, Spirochaetae, and Firmicute. Supplementation of xylanase in diets increased the relative abundance of Bacteroides and Gemmatimonadete. The higher hepatic glucokinase (GK) and glucose-6-phosphate dehydrogenase (G6PD) activities were observed in fish fed the xylanase supplementation diet. Accordingly, dietary xylanase supplementation upgraded the relative expressions of gk and g6pd genes in liver. In conclusion, optimum dietary xylanase supplementation (600-1200 U kg-1) could improve the growth performance, optimize the intestinal morphology structure and microbiota constitution, and enhance the ability of carbohydrate utilization of juvenile large yellow croaker.

Interactions of long-term food ration variation and short-term fasting on insulin-like growth factor-1 (IGF-1) pathways in copper rockfish (Sebastes caurinus).

Variation in food intake affects somatic growth by altering the expression of hormones in the somatotropic endocrine axis including insulin-like growth factor-1 (IGF-1). Here, we examined IGF-1 pathway responses to long- and short-term variation in food availability in copper rockfish (Sebastes caurinus), a nearshore Pacific rockfish important for commercial and recreational fisheries. Juvenile copper rockfish were raised under differing ration amounts (3% or 9% mass feed·g-1 fish wet mass·day-1) for 140 d to simulate 'long-term' feeding variation, after which some fish from both rations were fasted for 12 d to generate 'short-term' conditions of food deprivation. Rockfish on the 9% ration treatment grew more quickly than those on the 3% ration and were larger in mass, length, and body condition (k) after 152 d. Fish on the 9% ration had higher blood glucose than those on the 3% ration, with fasting decreasing blood glucose in both ration treatments, indicating that both long-term and short-term feed treatments altered energy status. Plasma IGF-1 was higher in rockfish from the 9% ration than those in the 3% ration and was also higher in fed fish than fasted fish. Additionally, plasma IGF-1 related positively to individual variation in specific growth rate (SGR). The positive association between IGF-1 and SGR showed discordance in fish that had experienced different levels of food and growth over the long-term but not short-term, suggesting that long-term nutritional experience can influence the relationship between IGF-1 and growth in this species. Rockfish on the 3% ration showed a lower relative abundance of gene transcripts encoding igf1 in the liver, but higher hepatic mRNAs for IGF binding proteins igfbp1a and igfbp1b. Fasting similarly decreased the abundance of igf1 mRNAs in the liver of fish reared under both the 9% and 3% rations, while concurrently increasing mRNAs encoding the IGF binding proteins igfbp1a, -1b, and -3a. Hepatic mRNAs for igfbp2b, -5a, and -5b were lower with long-term ration variation (3% ration) and fasting. Fish that experienced long-term reduced rations also had higher mRNA levels for igfbp3a, -3b, and IGF receptors isoforms A (igf1rA) and B (igf1rB) in skeletal muscle, but lower mRNA levels for igf1. Fasting increased muscle mRNA abundance for igfbp3a, igf1rA, and igf1rB, and decreased levels for igfbp2a and igf1. These data show that a positive relationship between circulating IGF-1 and individual growth rate is maintained in copper rockfish even when that growth variation relates to differences in food consumption across varying time scales, but that long- and short-term variation in food quantity can shift basal concentrations of circulating IGF-1 in this species.

Influence of a Dietary Vegetable Oil Blend on Serum Lipid Profiles in Large Yellow Croaker ( Larimichthys crocea).

Serum lipid metabolic responses are associated with certain metabolic disorders induced by dietary habits in mammals. However, such associations have not been reported in fish. Lipidomic analyses were performed to investigate fish lipid metabolic responses to a dietary vegetable oil (VO) blend and to elucidate the mechanism of how the dietary VO blend affects serum lipid profiles. Results showed that the dietary VO blend strongly affects serum lipid profiles, especially the ratio of triglyceride/phosphatidylcholine (TAG/PC), via inhibiting hepatic PC biosynthesis and facilitating hepatic and intestinal lipoprotein assembly. Studies in vitro suggested that changes of serum TAG/PC ratio may be partially attributed to altered fatty acid composition in diets. Additionally, the reduction of 16:0/18:1-PC induced by the dietary VO blend may play a role in abnormal lipid deposition through inhibiting PPARA-mediated activation of ß-oxidation. These findings suggested that the serum TAG/PC ratio might be a predictive parameter for abnormal lipid metabolism induced by dietary nutrition in fish.

Cottonseed protein concentrate (CPC) suppresses immune function in different intestinal segments of hybrid grouper ♀Epinephelus fuscoguttatus×♂Epinephelus lanceolatu via TLR-2/MyD88 signaling pathways.

Cottonseed protein concentrate (CPC) has similar amino acid composition compared with fish meal, and has the characteristics of low gossypol and low toxicity. The present study was conducted to investigate the growth performance, antioxidant capacity and different intestinal segments immune responses of hybrid grouper to replacement dietary fish meal ofCPC. Six iso-nitrogenous (50% crude protein) and iso-lipidic (10% crude lipid) diets were formulated: a reference diet (FM) containing 60% fishmeal and five experimental diets (12%, 24%, 36%, 48 and 60%) in which fishmeal protein was substituted at different levels by CPC to feed fish (initial body weight: 11 ±â€¯0.23 g) for 8 weeks. Thena challenge test with injection of Vibrio parahaemolyticus was conducted for 7 days until the fish stabilized. The results showed that specific growth rate (SGR) was the highest with 24% replacement level and feed conversion ratio (FCR)was significantly increased when the replacement level reached 48% (P < 0.05). The content of malonaldehyde (MDA) in the serum was significantly increased when the replacement level reached 36% (P < 0.05). The plica height in the proximal, mid and distal intestine were significantly decreased with the replacement level up to 48% (P < 0.05). Hepatic fat deposition wasaggravatedwhen the replacement level reached 36% (P < 0.05). The expression of IL-6, TNF-α, and IL-1ß mRNAs were significantly up-regulated (P < 0.05). The hepcidin mRNA expression was significantly down-regulated (P < 0.05). In proximal intestine (PI) and mid intestine (MI), IFN-γ mRNA expression was significantly up-regulated (P < 0.05). These results suggested that the CPC decreased hybrid grouper growth performance and inflammation function, and different inflammation function responses in PI,MI, and distal intestine (DI) were mediated partly by the TLR-2/MyD88 signaling pathway. According to the analysis of specific growth rate, the dietary optimum replacement level and maximum replacement level were estimated to be 17% and 34%, respectively.

Gastrointestinal and hepatic enzyme activities in juvenile silvery-black porgy (Sparidentex hasta) 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.

Profiles of gonadotropin-inhibitory hormone and melatonin during the sex change and maturation of cinnamon clownfish, Amphiprion melanopus.

The present study aimed to determine the relationship between melatonin and gonadotropin-inhibitory hormone (GnIH) and their effect on reproduction in cinnamon clownfish, Amphiprion melanopus. Accordingly, we investigated the expression pattern of GnIH, GnIH receptor (GnIH-R), and melatonin receptor (MT-R1) mRNA and protein, as well as the plasma levels of melatonin, during sex change in cinnamon clownfish. We found that GnIH and MT-R1 mRNA and melatonin activity were higher in fish with mature brain than in fish with developing gonads, and using double immunofluorescence staining, we found that both GnIH and MT-R1 proteins were co-expressed in the hypothalamus of cinnamon clownfish. These findings support the hypothesis that melatonin plays an important role in the negative regulation of maturation and GnIH regulation during reproduction.

Immune responses and stress resistance in red sea bream, Pagrus major, after oral administration of heat-killed Lactobacillus plantarum and vitamin C.

The present study evaluated the interactive benefits of dietary administration of heat-killed Lactobacillus plantarum (LP) and vitamin C (VC) on the growth, oxidative status and immune response of red sea bream (Pagrus major). A diet without LP and VC supplements was employed as a control diet. Four other test diets with 0 or 1 g LP kg(-1) combined with 0.5 or 1 g VC kg(-1) (2 × 2 factorial design) were fed to red sea bream (2 ± 0.01 g) for 56 days. A significant interaction was found between LP and VC on final body weight (FNW), weight gain (WG), hematocrit (HCT), serum bactericidal (BA) and lysozyme (LZY) activities, mucus LZY and peroxidase (PA) activities, nitro blue tetrazolium (NBT), catalase, mucus secretion and tolerance against low salinity stress test (LT50) (P < 0.05). In addition, FNW, WG, specific growth rate, feed and protein efficiency ratio, serum (BA, LZY, PA and NBT), mucus (LZY and PA), superoxide dismutase, malondialdehyde and mucus secretion were significantly affected by either LP or VC (P < 0.05). Furthermore, only LP was a significant factor on survival, plasma total cholesterol, mucus BA and alternative complement pathway (P < 0.05). However, VC supplementation affected on HCT and LT50. Interestingly, fish fed with both LP at 1 g kg(-1) diet with VC at 0.5 or 1 g kg(-1) diet showed higher growth, humoral and mucosal immune responses, anti-oxidative status, mucus secretion and LT50 as well as decreased plasma, triglyceride and total cholesterol levels than the fish fed control diet (P < 0.05). These results demonstrated that dietary LP and VC had a significant interaction for red sea bream with the capability of improving growth performance and enhancing stress resistance by immunomodulation.

Dietary supplementation of Zeolite on growth performance, immunological role, and disease resistance in Channa striatus against Aphanomyces invadans.

Epizootic Ulcerative Syndrome (EUS) caused by Aphanomyces invadans which is a primary fungal parasitic pathogen, inflicts serious economic loss in tropical freshwater fish including snakehead murrel, Channa striatus. In the present study with an aim to circumvent the adverse effects of the traditional measures in graded levels (2%, 4%, and 6%) of Zeolite enriched diet on growth performance, hematology, immunological response, and disease resistance in C. striatus against A. invadans is reported. The final weight (FW), specific growth rate (SGR), feed conversion ratio (FCR), protein efficiency ratio (PER), and average daily gain (ADG) were significantly high in infected fish fed with 4% or 6% Zeolite incorporated diets on 4th week. The maximum survival rates (SR) of 96% and 98% were observed when fed with 2% or 4% diets on 4th week. Similarly, the white blood cell (WBC), red blood cell (RBC), hematocrit (Hct), mean corpuscular volume (MCV), and mean corpuscular haemoglobin concentration (MCHC) were significantly high when fed with any Zeolite enriched diet. However, the haemoglobin (Hb) and mean corpuscular haemoglobin (MCH) were significantly high with 4% and 6% Zeolite diets. The total protein and globulin were significantly high with 4% and 6% diets; the albumin, glucose, cholesterol, and triglyceride were significantly elevated with any enriched diet. The 4% and 6% Zeolite diets significantly enhanced the phagocytic activity on 2nd week but the 2% diet could increase it on 4th week. The respiratory burst (RB) activity, complement activity, and lymphocyte proliferation level were significantly enhanced with 4% and 6% Zeolite diets on weeks 1 and 2 while with 2% diet on 4th week. All enriched diets significantly increased the lysozyme activity during the experimental period. Superoxide anion (SOA) production significantly enhanced with 6% diet on weeks 1 and 2 whereas with 2% diet on week 4. Lower cumulative mortality of 10% and 15% was found with 4% and 6% Zeolite diets whereas a higher mortality (20%) was observed with 2% diet. The present study suggests that dietary supplementation with 4% or 6% Zeolite significantly increase growth performance, hemato-biochemical changes, immunological response, and disease resistance in C. striatus against A. invadans.

Effects of Modified Handling on the Physiological Stress of Trawled-and-Discarded Yellowfin Bream (Acanthopagrus australis).

Modified handling is often claimed to reduce (sub-)lethal impacts among organisms caught-and-released in fisheries. Improving welfare of discarded fish warrants investigation, when their survival is of both economic and ecological importance. In this study, juvenile yellowfin bream (Acanthopagrus australis) were trawled in an Australian penaeid fishery and then discarded after on-board sorting in either dry or water-filled (modified) trays and with delays in starting sorting of either 2 or 15 mins. Blood plasma cortisol, glucose and potassium were sampled immediately from some yellowfin bream, while others were placed into cages (with controls) and sampled after five days. Irrespective of their on-board handling, all trawled fish incurred a relatively high acute stress response (i.e. an increase in Mean ± SE cortisol from a baseline of <4 to 122.0 ± 14.9 ng/mL) that was mostly attributed to the trawling process, and exacerbated by variation in key parameters (low salinity, changes in water temperature and the presence of jellyfish Catostylus mosaicus in catches). When C. mosaicus was present, the potassium concentrations of fish sampled immediately after sorting were significantly elevated, possibly due to nematocyst contact and subsequent inhibition of ion pumps or cytolysis. Stress also increased during handling in response to warmer air temperatures and longer exposure. While most fish had substantially recovered by 120 hours after discarding, deploying selective trawls (to reduce jellyfish) for short periods and then quickly sorting catches in water would benefit discard welfare.

Effect of fishmeal replacement by soy protein concentrate with taurine supplementation on growth performance, hematological and biochemical status, and liver histology of totoaba juveniles (Totoaba macdonaldi).

The effect of dietary inclusion of soy protein concentrate (SPC) and simultaneous supplementation with taurine on the growth, hematology, blood biochemistry, and liver histology of totoaba (Totoaba macdonaldi) juveniles was assessed. Four isoproteic and isolipidic diets were formulated containing either 30 or 60% of SPC (diets S30 and S60), supplemented or not with 1% of taurine (diets S30T and S60T). A fishmeal-based diet formulated for totoaba nutritional requirements, without SPC and taurine supplementation, was used as a reference diet. Triplicate groups of 32 totoaba juveniles (average body weight 7.5 ± 0.6 g) were fed these diets for 45 days. Results showed that growth performance in fish fed S30, S30T, and S60T was similar to fish fed the reference diet. Red blood cells and hematocrit in fish fed with supplemented taurine in both levels of SPC (S30T and S60T) were similar to the fish fed the RD; the addition of taurine improved the state of hydration of totoaba. Plasmatic hemoglobin in fish fed the lower SPC level was similar to fish fed the RD. The mean corpuscular hemoglobin concentration in fish fed S30T was similar to fish fed the RD, taurine supplementation prevented the development of hypochromic anemia in this group of fish. Plasmatic albumin in fish fed S30 was similar to fish fed the RD. Plasmatic total protein and globulin concentration increased and AL:GLB (albumin:globulin ratio) decreased in fish fed the SPC-based diets despite taurine supplementation. The protein profile showed that taurine supplementation did not prevent a possible inflammatory process (increased globulins, decreased AL:GLB) in juvenile totoaba fed both levels of SPC. Glucose concentration was similar in fish fed S30, S30T, and S60T. The histological hepatic index was highest in fish fed S60. These results suggest that with an appropriate nutritional level, taurine may play an important modulatory role in the hematology and blood biochemistry status in totoaba fed SPC-based diets, contributing to the enhancement of an overall healthy growth performance.

Enhancement of reproductive performances of Gangetic leaffish, Nandus nandus through up regulation of serum Ca²âº concentration, improved morphological alteration of liver and ovary with dietary polyunsaturated fatty acids.

Incorporation of polyunsaturated fatty acids (PUFAs) as biofunctional compounds with feed is an effective way for gonadal maturation without any hazardous effects on animal health, and thus it is possible to save the vulnerable species from the danger of extinction. In the present study sperm quality, level of Ca(2+) concentration in serum, histological structure of the liver and developmental stages of ovary of an endangered fish species, Nandus nandus were investigated for the confirmation of the positive effects of PUFAs in reproduction and gonadal maturation. Fishes were collected from Brahmaputra River, Mymensingh, Bangladesh. Treated group was fed 1% squid extracted phospholipid supplemented diet that was mixed with silver carp fish muscle where as controlled group was fed the same except phospholipid. For histology of liver and gonads, samples were dehydrated, cleaned and infiltrated, embedded in paraffin wax and sectioned. After that, the samples were stained with hematoxylin and eosin. The photomicrographs of the stained samples were taken by using light microscope. In comparison with the control group, treated group exhibited higher gonadal maturation which resulted in spontaneous spawning. Treated female demonstrated advanced gonadal developmental stages in comparison with the controlled female during different months. During spawning season, lipid granules and normal morphological alteration were observed in case of treated fish liver, whereas less lipid granules with more histological alteration of liver were observed in control group. Serum Ca(2+) concentration in treated female was found significantly higher (P < 0.01) in contrast to the controlled female during the breeding season which was an indicator of the augment of estrogen secretion during ovarian maturation. Better sperm quality, early maturation of oocytes, less histological alteration of liver hepatocytes and spontaneous spawning performances of PUFA-treated fish were as a result of the efficiency of PUFAs in enhancing maturation. The experiment suggests that supplementation of dietary PUFAs improve the spawning performances of fish.

Effects of palm oil blended with oxidized fish oil on growth performances, hematology, and several immune parameters in juvenile Japanese sea bass, Lateolabrax japonicas.

A 60-day feeding trial was conducted to determine the effects of palm oil blended with oxidized and non-oxidized fish oil on growth performances, hematology, and non-specific immune response in juvenile Japanese sea bass, Lateolabrax japonicas. Japanese sea bass (1.73 ± 0.01 g) were fed seven experimental diets containing 100 g/kg of dietary lipid in forms of palm oil (10P), fish oil (10F), fish oil blended with palm oil at different ratios, 6:4 (6F4P) and 4:6 (4F6P), oxidized fish oil (10OF), and oxidized fish oil blended with palm oil at different ratios, 6:4 (6OF4P) and 4:6 (4OF6P). After the feeding trial, the following results were illustrated. No significant effects were observed in survival, feed conversion ratio, condition factor, and hematocrit after feeding with experimental diets for 60 days. The relatively higher specific growth rate and hematology were observed in 6F4P. Furthermore, both palm oil and oxidized fish oil acted as a negatively on serum lysozyme activity (P < 0.05). This study suggested that a ration of 6F4P is recommended as an innocuous ratio for Japanese sea bass. Furthermore, according to the present investigation, palm oil seems to have the ability to improve the protein efficiency when added to oxidized fish diets as well as a positive trend to the growth performance (P > 0.05).

Effect of dietary vitamin C on the growth performance and innate immunity of juvenile cobia (Rachycentron canadum).

This study was conducted to evaluate the effects of dietary vitamin C on growth performance, hematologic parameters and innate immune responses in juvenile cobia, Rachycentron canadum. Seven practical diets were formulated to contain 0.0 (as the basal diet), 13.6, 27.2, 54.4, 96.6, 193.4 and 386.5 mg ascorbic acid equivalent kg(-1) diet. Each diet was fed to triplicate groups of juvenile cobia with initial body weight of 5.5 g in 500-L cylindrical fiberglass tank. The results of 8 weeks feeding trial showed that typical vitamin C-deficient signs such as spinal deformation and body nigrescence were observed in the fish fed the basal diet. Fish fed the basal diet had significantly lower weight gain, specific growth rate (SGR), protein efficiency ratio (PER) and feed efficiency (FE) than those fed the diets supplemented with vitamin C, but no significant differences were observed among diets supplemented with vitamin C. However, survival rate was significantly affected by the dietary vitamin C levels, fish fed the basal diet had lower survival rate than those fed the diets supplemented with vitamin C. The ascorbic acid concentration in liver was correlated positively with the dietary vitamin C levels, however, the thiobarbituric acid reactive substances (TBARS) concentrations in liver was not significantly affected by the dietary vitamin C levels, although, fish fed the basal diet had the highest TBARS values among all treatments. The activities of serum lysozyme, superoxide dismutase (SOD), alkaline phophatase (AKP) and total immunoglobulin (Ig) were significantly influenced by the dietary vitamin C levels, fish fed the basal diet had lower lysozyme, SOD, AKP and total Ig than those fed diets supplemented with vitamin C. The serum glucose and triglyceride concentrations were significantly affected by the dietary vitamin C levels. Fish fed the basal diet had lower red blood cell and hemoglobin values than those fed the vitamin C supplemented diets. The challenge experiment with Vibrio harveyi showed that lower cumulative survival was in fish fed the unsupplemented diet, the cumulative survival were significantly increased with increase of the dietary ascorbic acid levels from 13.6 to 96.6 mg kg(-1), while the cumulative survival reached plateau when dietary ascorbic acid levels increased from 96.6 to 386.5 mg kg(-1). These results indicated that dietary vitamin C did significantly influence on growth performance and immune response of juvenile cobia.

Impact of diets with different proportions of linseed and sunflower oils on the growth, liver histology, immunological and chemical blood parameters, and proximate composition of pikeperch Sander lucioperca (L.).

The aim of the study was to determine the impact of applying different proportions of linseed (LO) and sunflower (SFO) oils in pikeperch diets on growth, histological changes in the liver, immunological and blood chemical parameters. The fish were fed isoenergetic and isoprotein feeds containing SFO (group 100SFO) or LO (group 100LO) in quantities of 67 g kg/feed, and a mixture of oils: 47 g SFO and 20 g LO kg/feed (group 70SFO/30LO) and 20 g SFO and 47 g LO kg/feed (group 30SFO/70LO). Dietary ratios of polyunsaturated fatty acids from the n-3 and n-6 series (n3/n6 index) were 0.36-2.15. Pikeperch were reared for 56 days in three replicates for each dietary treatment. Various dietary oils and ratios of n3/n6 did not impact fish growth, feed conversion ratio, viscerosomatic and hepatosomatic index, and size of the hepatocytes. Feeding the fish high quantities of LO and SO oils (groups 100LO and 100SFO) reduced the immunological response of the phagocytes and lymphocytes in the fish. Moreover, this resulted in significant differences among groups in the quantity of linolenic and linoleic acid in whole fish bodies, viscera, fillets, and livers. Various quantities of vegetable oils in the fish diets did not impact the quantity of arachidonic, eicosapentaenoic and docosahexaenoic acid in the fillets and livers. The immunological index and low quantities of linoleic acid in the fillets obtained in group 30SFO/70LO indicate that the n3/n6 dietary ratio of 1.35 was the most advantageous for feeding juvenile pikeperch feeds with vegetable oils.

Temporal and geographical trends in the genotoxic effects of marine sediments after accidental oil spill on the blood cells of striped beakperch (Oplegnathus fasciatus).

To determine the impact of genetic toxicity caused by the Hebei Spirit oil spill on December 7, 2007, we measured DNA damage in the blood cells of striped beakperch in vitro after exposure to extracts from sediments in the Taean area. The objective of this study was to investigate temporal changes of toxic effects caused by residual PAHs in the sediments up to 18 months after an oil spill. In conclusion, DNA damage had reduced over this 18-month period; that is, the sediments recovered quickly from the oil pollution. In addition, statistically significant correlations between PAHs and DNA damage were observed. Because the comet assay is sensitive to DNA damage induced by genotoxic substances from the polluted sediments, the comet assay can be considered a useful tool as a biomarker in investigating genetic toxicity in environmental monitoring and elucidating the recovery of oil pollution after oil spill as well.

Influence of ß-glucan on innate immunity and resistance of Lutjanus guttatus to an experimental infection of dactylogyrid monogeneans.

The present study investigated the effect of ß-1,3/1,6-glucan on growth, haematology, innate immunity and resistance against dactylogyrids on the spotted rose snapper (Lutjanus guttatus). Fish were fed during 5 weeks with commercial diet (control group) and same diet supplemented with three levels of ß-glucans (0·05%, 0·1% and 0·5%/kg feed). The results showed that at concentrations of 0·05% and 0·1%, fish growth was enhanced, and in weeks 2 and 4, an increase in cellular responses such as percentage of monocytes, neutrophils, respiratory burst activity and nitric oxide activity was observed. In diet with 0·5%ß-glucans, changes were registered at the end of the experiment. At week 2, 0·05%ß-glucans showed the best response to most of the analysed parameters. In a second trial, diet with 0·05%ß-glucans was chosen to prove its effect on the resistance of infected fish with monogeneans. The results showed that fish reduce significantly the number of dactylogyrids, and parameters such as WBC, percentage of lymphocytes, neutrophils and eosinophils were increased. In addition, WBC and percentage of thrombocytes increased in the control (+). The ß-glucans have the potential to be use in diet formulations of the spotted rose snapper and to limit the adverse effects of dactylogyrids.

Protective effect of herbal and probiotics enriched diet on haematological and immunity status of Oplegnathus fasciatus (Temminck & Schlegel) against Edwardsiella tarda.

This study determines the effect of diet enriched with the herb Baical skullcap Scutellaria baicalensis, and/or probiotics Lactobacillus sakei BK19 in rock bream, Oplegnathus fasciatus (32 ± 3 g) against Edwardsiella tarda. The changes in haematological parameters, innate immune response, and disease resistance were investigated after 1, 3, and 6 weeks. The white blood cell count (WBC: 10(4) mm(-3)), red blood cell count (RBC: 10(6) mm(-3)), and haemoglobin (Hb: g dl(-1)) levels significant increased (P < 0.05) with mixed diet on 3rd and 6th week and probiotics enriched diet on 6th week. The haematocrit (Ht: %) level significantly increased (P < 0.05) when fed with mixed diet on weeks 1-6. Interestingly, in mixed diet group the lymphocytes (LYM), monocytes (MON), and neutrophils (NEU) significantly increased from week 1-6. The eosinophils (EOS) significantly increased in all the treated groups. In the probiotics or mixed diet groups the total protein (TP: g dl(-1)) increased significantly on weeks 3 and 6. The serum lysozyme activity significantly was enhanced in all the treated groups indicating an increase in the innate immunity level. Serum complement, antiprotease activities, reactive oxygen species (ROS) and reactive nitrogen species (RNS) production significantly increased from week 1-6 with mixed diet. The maximum protection against E. tarda was recorded in mixed diet group with a minimum cumulative mortality of 20% and a high relative percent survival (RPS) of 72.84. In the probiotics and herbal diet groups the cumulative mortality was 25% and 35% and RPS was 68.63 and 59.42, respectively. This study indicates that administration of probiotics or mixed diets can effectively minimize the mortality and restore the altered hematological parameters and enhancing the innate immunity in O. fasciatus against E. tarda.