Search

Aquaculture of cobia (Rachycentron canadum) is still incipient in Brazil, as well as the sale of its meat. However, there is a market demand for this product in the state of Rio de Janeiro. The salting process for the meat of cultivated cobia is a way of preserving and marketing the product for the growers. Thus, the present study aimed to assess the chemical properties of salted cobia meat. Market-sized cobia grown in net-tanks located in Baía de Ilha Grande, Angra dos Reis, Rio de Janeiro, Brazil were used. The fish were eviscerated (gutted), beheaded and lightly flattened. The fillets “charutos” were then subjected to brine salting for 6 days, immersed in saturated brine at refrigeration temperature. After the preparation of the product, analyzes of percent composition, chloride content and lipid profile were performed. The product had high concentrations of protein (20.16%), lipids (19.88%) and 6.56% of total chloride. Lipid profile assessment showed significant percentages of palmitic (6.66%) and oleic (4.99%) acids. Therefore, it is concluded that the salted meat of cobia has good nutritional quality, and the product is a source of palmitic and oleic acids that help preventing cardiovascular diseases and lowering cholesterol levels.

Cobia (Rachycentron canadum) is economically important fish with good prospects because of fast growing and easily cultured. Cobia is usually processed by many methods including steaming. The purposes of this research were to determine the effect of steaming process on proximate and amino acids composition. The chemical composition of fresh and steamed cobia’s meat were determined by proximate analysis. Amino acid compositions of fresh and steamed cobia’s meat were measured using HPLC (high performance liquid chromatography). Steaming process reduced 11.31% of water, 1.06% of ash, 26.04% of fat, and 9.11% of protein. Fresh and steamed cobia’s meat contained 17 amino acids consisting of 9 essential amino acids and 8 nonessential amino acids. The highest essential amino acid in fresh cobia’s meat was arginine (2,262 mg/100 g) and the highest nonessential amino acid was glutamic acid (3,894 mg/100 g). Steaming process reduced amino acids generally. The highest essential amino acid in steamed cobia’s meat was leucine (1,379 mg/100 g) and the highest nonessential amino acid was glutamic acid (2,370 mg/100 g). Taurine content of fresh cobia’s meat was 120.84 mg/100 g and changed into 94.33 mg/100 g after steaming process.

The production of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) concentrate from cobia liver oil by acetone fractionation of fatty acid salts was investigated in this study. A three-level-three-factor Box-Behnken design was used to evaluate the effects of reaction time, amount of NaOH added, and acetone ratio on the responses (DHA and EPA content and recovery). The results showed that the amount of NaOH added was the most important factor in the process. The DHA content showed an inverse relation with EPA content and recovery, whereas its content increased proportionally with the amount of NaOH added. With a reaction time of 1.51 h, amount of NaOH added at 0.65 times the molar equivalent of free fatty acid (FFA), and acetone ratio at 13.92, a maximum recovery of DHA + EPA was 98.14%, and the obtained concentrate contained 71.23% DHA + EPA. Finally, the lipase-catalyzed esterification of the DHA + EPA concentrate with glycerol was carried out. The acetone fractionation of fatty acid salts is an efficient technique for producing DHA +EPA concentrate. The DHA +EPA concentrate can be used as starting materials for the production of functional lipids to provide n-3 polyunsaturated fatty acids to the consumers.

This experiment was conducted to investigate the effects of dietary lipid-to-carbohydrate ratio on growth and carbohydrate metabolism in juvenile cobia (Rachycentron canadum). Six isonitrogenous diets were prepared to vary in lipid-to-carbohydrate ratio (g/g) as follows: D1, 2.26; D2, 1.31; D3, 0.78; D4, 0.47; D5, 0.34; and D6, 0.23. Cobias were fed to satiety for 8 weeks. The weight gain and protein efficiency ratio in D1 group were significantly lower than those in other groups (P

Juvenile cobia (Rachycentron canadum), a carnivorous fish, was chosen to examine the effects of methionine (Met) supplementation of low fishmeal diets on growth and the expression of key genes related to hepatic lipogenesis and glucose metabolism. Seven isonitrogenous and isolipidic diets were formulated to contain 7.2, 9.0, 10.0, 12.4, 14.1, 16.3 and 18.6 g/kg dietary Met levels. Healthy cobia (initial average weight ± SE = 9.79 ± 0.04 g) were randomly assigned into seven groups in triplicate with 40 individuals per sea cage for 8 weeks. The results showed that the weight gain rate (WGR) of fish increased as the dietary Met was increased up to 12.4 g/kg and then decreased. The expression of insulin‐like growth factor‐I (IGF‐I) and target of rapamycin (TOR) genes was inhibited by the Met‐deficient diets. The mRNA levels of fatty acid synthase (FAS) and sterol regulatory element‐binding protein‐1 (SREBP1) genes increased with increasing dietary Met until 12.4 g/kg after which the former remained constant, whereas the latter decreased from 12.4 to 18.6 g/kg Met. The mRNA levels of pyruvate kinase (PK) increased as the dietary Met levels increased, reaching a peak at 12.4 g/kg, and then decreased with further increases in Met. However, the mRNA levels of phosphoenolpyruvate carboxykinase (PEPCK) decreased as the dietary Met was increased up to 12.4 g/kg and then remained constant from 12.4 to 18.6 g/kg Met. In conclusion, based on the straight broken‐line analysis of WGR against dietary Met levels, the optimal dietary Met requirement for juvenile cobia was estimated to be 12.4 g/kg (26.9 g/kg dietary protein). A diet with the optimal level of Met induces fish growth and is associated with increased IGF‐I and TOR.

An 8-week feeding experiment was conducted to investigate the effects ofdl-methionine (Met) supplementation in a low-fishmeal diet on growth, key gene expressions of amino acid transporters and target of rapamycin (TOR) pathway in juvenile cobia,Rachycentron canadum. Seven isonitrogenous and isolipidic diets were formulated, containing 0·72, 0·90, 1·00, 1·24, 1·41, 1·63 and 1·86 % Met. Weight gain and specific growth rates increased gradually with Met levels of up to 1·24 % and then decreased gradually. In dorsal muscle, mRNA levels of ASCT2 in the 1·00 % Met group were significantly up-regulated compared with 0·72, 1·63, and 1·86 %. The insulin-like growth factor-I (IGF-I) mRNA levels in the dorsal muscle of fish fed 1·00 and 1·24 % Met were higher than those in fish fed other Met levels. In addition, fish fed 1·24 % Met showed the highest mRNA levels of TOR and phosphorylation of TOR on Ser2448. The phosphorylation of ribosomal p70-S6 kinase (S6K) on Ser371in the dorsal muscle of fish fed 1·86 % Met was higher than those in the 0·72 % group. In conclusion, straight broken-line analysis of weight gain rate against dietary Met level indicates that the optimal Met requirement for juvenile cobia is 1·24 % (of DM, or 2·71 % dietary protein). Met supplementation in a low-fishmeal diet increased cobia growth via a mechanism that can partly be attributed to Met’s ability to affect the TOR/S6K signalling pathway by enhancing ASCT2 and IGF-I transcription in cobia dorsal muscle.

Teleost fishes are diverse and successful, comprising almost half of all extant vertebrate species. It has been suggested that their success as a group is related, in part, to their unique O2 transport system, which includes pH-sensitive hemoglobin, a red blood cell β-adrenergic Na+/H+ exchanger (RBC β-NHE) that protects red blood cell pH, and plasma accessible carbonic anhydrase which is absent at the gills but present in some tissues, that short-circuits the β-NHE to enhance O2 unloading during periods of stress. However, direct support for this has only been examined in a few species of salmonids. Here, we expand the knowledge of this system to two warm-water, highly active marine percomorph fish, cobia (Rachycentron canadum) and mahi-mahi (Coryphaena hippurus). We show evidence for RBC β-NHE activity in both species, and characterize the Hb-O2 transport system in one of those species, cobia. We found significant RBC swelling following β-adrenergic stimulation in both species, providing evidence for the presence of a rapid, active RBC β-NHE in both cobia and mahi-mahi, with a time-course similar to that of salmonids. We generated oxygen equilibrium curves (OECs) for cobia blood and determined the P50, Hill, and Bohr coefficients, and used these data to model the potential for enhanced O2 unloading. We determined that there was potential for up to a 61% increase in O2 unloading associated with RBC β-NHE short-circuiting, assuming a - 0.2 ∆pHa-v in the blood. Thus, despite phylogenetic and life history differences between cobia and the salmonids, we found few differences between their Hb-O2 transport systems, suggesting conservation of this physiological trait across diverse teleost taxa.

Cobia (Rachycentron canadum) is an important cultured marine fish species in southern China. It is characterized by fast growth. Due to the effects of climate change on water oxygen levels and seawater temperatures, the understanding of the influence of environmental changes on cobia culture has become important. In this study, to explore the stress and adaptability of cobia under hypoxia-reoxygenation conditions, the fish were exposed to an oxygen-deficient environment with dissolved oxygen (DO) level of 2.64 ± 0.25 mg/L. Serum liver function target, lipid metabolism-related enzymes and the serum antioxidant capability were detected in cobia under acute hypoxic stress after which fish returned to normal DO level (6.34 ± 0.15 mg/L) at 8, 24 and 48 h. Conventional paraffin sectioning and hematoxylin and eosin (H-E) staining were used to observe gill and liver tissues of cobia by electron microscopy. After hypoxic stress, the activities of alkaline phosphatase (ALP), total protein (TP), albumin (ALB), triglyceride (TG), total cholesterol (TC) and superoxide dismutase (SOD) in cobia decreased. Under acute hypoxic stress, the gill patches of the fish were contracted and slightly curved. Liver disorder and vacuoles appeared between liver tissues. After reoxygenation, SOD and catalase (CAT) were recovered to the level of the control group with time, and all peaks appeared. The gill and liver of fish were also recovered with time. The results showed that hypoxic stress could cause oxidative damage to cobia.

Made available in DSpace on 2021-06-25T15:07:11Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-08-30 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Centro de Biologia Marinha da Universidade de Sao Paulo (CEBIMar) This study aimed to investigate the influences of alternative lipid sources rich in saturated and monounsaturated fatty acids (SFA and MUFA) supplemented with long-chain polyunsaturated fatty acids (LC-PUFA) on production performance and lipid metabolism of Rachycentron canadum (cobia) juveniles. An 8-week feeding trial was carried out using four isoproteic and isolipidic diets as follows: FO-D (fish oil, as control diet), SFA-D (rich in SFA), MIX-D (same levels of SFA and MUFA), and MUFA-D (rich in MUFA). Experimental diets were supplemented with arachidonic acid (ARA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) (3, 5, and 10 g kg(1), respectively). The growth performance, fatty acid (FA) profile of liver and muscle, hepatocyte morphology, and gene expression related to the FA synthesis and oxidation on the liver were examined. In general, production performance was not impaired in fish-fed FO-free diets, supporting the hypothesis that alternative lipid sources could be used in cobia's aquafeed formulations when the LC-PUFA are adequately supplemented. High dietary SFA levels were disproportionally deposited the liver and muscle. Contrariwise MUFA was mainly deposited in the liver and muscle, reflecting the dietary inclusion levels. The main FA influencing this pattern were 12:0 and 18:1n-9. The expression of fatty acid synthase (fas) was up-regulated in the FO-D group compared to SFA-D and MIX-D groups. There were no differences in the relative expressions of carnitine palmitoyltransferase 1 (cpt-1 alpha) and lipase lipoprotein (lpl). The liver morphology results indicated that fish-fed SFA-D presented a smaller lipid vacuoles area than those fed other experimental diets. This study shows that SFA with shorter carbon chains such as 12:0 can be administered in cobia aquafeeds to stimulate these molecules' catabolism, providing energy for growth, and retaining LC-PUFAs in tissues, especially in the muscle, exhibiting a healthier fillet for consumers. Univ Sao Paulo, Dept Fisiol, Inst Biociencias, Rua Matao,Trav 14,321, BR-05508090 Sao Paulo, SP, Brazil Univ Sao Paulo CEBIMar USP, Ctr Biol Marinha, Rodovia Manoel Hipolito Rego,Km 131,5, BR-11612109 Sao Sebastiao, SP, Brazil CSIRO Agr & Food, Livestock & Aquaculture Program, Bribie Isl Res Ctr, Woorim, Qld 4507, Australia Univ Autonoma Baja California UABC, Inst Invest Oceanol, Km 107 Carretera Tij Eda, Ensenada 22860, Baja California, Mexico Univ Estadual Paulista Julio de Mesquita Filho CA, Ctr Aquicultura, Via Acesso Prof Paulo Donato Castellane S-N, BR-14884900 Jaboticabal, SP, Brazil UABC, Inst Invest Oceanol, CONACYT, Ensenada, BC, Mexico Univ Mogi das Cruzes, Nucleo Integrado Biotecnol, Ave Dr Candido Xavier Almeida Souza 200, BR-08780911 Mogi Das Cruzes, SP, Brazil Univ Estadual Paulista Julio de Mesquita Filho CA, Ctr Aquicultura, Via Acesso Prof Paulo Donato Castellane S-N, BR-14884900 Jaboticabal, SP, Brazil FAPESP: 2019/092469 FAPESP: 2014/163207 FAPESP: 2017/067650 FAPESP: 2019/260180

Cobia, Rachycentron canadum, is a medium-size marine fish with emerging global potential for offshore aquaculture. The processing waste, cobia liver, is a raw material rich in polyunsaturated fatty acid oils. In this study, an environmentally friendly green process, aqueous extraction (AE), was used to extract the cobia liver oil. The effect of cooking time and substrate water ratio on the oil extractability was investigated herein. The cooking time of 15 min, and substrate water ratio of 1:2 obtained the highest extraction efficiency. However, the oil extractability was only 18.8%. Thus, enzyme-assisted aqueous extraction (EAAE) was used to increase oil extractability and recovery of protein hydrolysates. The commercial proteases&mdash, including alcalase, papain, trypsin, and pepsin&mdash, were employed in pretreated cobia liver in order to increase oil release during AE. The EAAE results showed that maximum oil extractability was 38% by papain pretreatment. EAAE greatly improved the extraction efficiency, the oil extractability was double than that of AE (18.8%). The fatty acid profiles revealed that &omega, 3 polyunsaturated fatty acid contents of extracted oil obtained from AE and EAAE were 21.3% and 19.5%, respectively. Besides, the cobia liver hydrolysates obtained from EAAE by alcalase, papain, pepsin, and trypsin pretreatment showed scavenge DPPH radical activity with EC50 values of 0.92, 1.03, 0.83, and 0.53 mg, respectively. After in vitro simulated gastrointestinal digestion, the protein hydrolysates exhibited scavenge DPPH radical activity with EC50 values of 1.15, 1.55, 0.98, and 0.76 mg for alcalase, papain, pepsin, and trypsin, respectively. The study showed that the EAAE process can be used for extracting fish oil from fish waste while simultaneously obtaining the protein hydrolysates with antioxidant activity.

This study investigates the effects of three medicinal herbal extracts, namely Bidens pilosa (BPE), Lonicera japonica (LJE), and Cyathula officinalis (COE), on nonspecific immune parameters of cobia (Rachycentron canadum) in vitro and in vivo. During in vitro tests, BPE treatment increased reactive oxygen species (ROS) production in a dose-dependent manner in primary head kidney leukocytes. Similarly, ROS production rates were enhanced by LJE (50 and 100 mg/ml) and COE (100 mg/ml). This suggests that these three herbal extracts possess immunostimulating properties. We then conducted two feeding trials to examine the effects of these three herbal extracts on growth and innate immune parameters of cobia, and sought an optimal dietary supplementation proportion required for activating the non-specific immune responses. In the first trial, we supplemented the diet with 1, 5, or 10% of the individual extracts. After a ten-week feeding trial, no negative impacts on weight gain, feed conversion rate, and survival rate were observed in fish offered experimental diets. Further, ROS production, phagocytic capacity of the head kidney leukocytes, and serum lysozyme activity were enhanced by differing degrees in fish fed the herbal extracts compared to fish in the control group. A similar albumin/globulin ratio was seen between each experimental group and the control group regardless of the type and dose of herbal extract used, indicating these medicinal herbal extracts are safe for cobia. We then performed a 30-day feeding trial with lower extract concentrations (1, 3, and 5% of the diet) to identify dose responses in cobia at various time points so that we could establish a cost-effective manner of administering the three extracts for cobia. All BPE fed fish had higher ROS production compared to the control group, while phagocytosis rate and index were simultaneously raised in only the BPE30 group (3% BPE). Immune parameters such as ROS production, phagocytic rate, and serum lysozyme activity were triggered when fish received 30 g LJE per kg of feed. However, ROS production only increased in the LJE10 group (1% LJE) on day 30 and was not enhanced in the LJE50 group (5% LJE). Additionally, although the phagocytic rate and phagocytic index were induced in the LJE50 group, serum lysozyme activity was not elevated in this group (LJE50) at any time point examined. ROS production was greatly improved in all COE fed groups, but only the COE30 group (3% COE) showed prolonged enhanced phagocytic rate over the 30-day feeding trial.

Three studies were conducted with juvenile cobia, Rachycentron canadum: (Study 1) a 10‐week feeding trial within floating net cages to test the nutritional efficacy of different dietary feeding regimes (trash‐fish control diet, a semimoist diet, an in‐house dry formulated diet, and a commercial cobia feed); (Study 2) a 10‐week feeding trial within an indoor water‐recirculating tank‐based system to test the nutritional efficiency of different potential dietary fishmeal replacers (poultry byproduct meal, soy protein concentrate, feather meal), a diet without taurine supplementation, and a commercial cobia feed; and (Study 3) estimation of the essential amino acid (EAA) requirements of cobia based on EAA whole‐body composition in fast‐growing cobia fed a trash‐fish‐based diet. Fish performance in terms of growth and feed efficiency was the greatest within the outdoor net‐cage feeding trial, with fish fed the control trash‐fish‐based diet exhibiting the best performance. Although fish growth was poorer within the indoor feeding trials, fish performance was similar for most diets, with apparent crude protein digestibility coefficients of over 75% being obtained in all experimental diets in both feeding trials. The estimated EAA requirements of cobia obtained during this study were similar to those reported for other similar marine carnivorous fish species.

The study examined the effects of supplemental organic selenium (Se) extracted from selenoyeast on the growth performance, glutathione peroxidase (GPx) activity, biochemical status and liver histochemistry of juvenile cobia Rachycentron canadum. Six experimental diets were prepared supplemented with Se with total concentration of 1.52 (Se-1.52), 1.93 (Se-1.93), 2.29 (Se-2.29), 2.71 (Se-2.71) and 3.14 (Se-3.14) mg/kg of total Se in the diets and a fishmeal-based control diet without Se supplementation containing 1.15 (Se-1.15) mg/kg of Se was used as control. Experimental diets were fed to the fish of six treatment groups in triplicate twice daily for 8 weeks. Juvenile cobia fed dietary Se of 1.93, 2.29 and 2.71 mg/kg showed increased final body weight (FBW), specific growth rate (SGR) and feed intake (FI) than the fish fed the control diet. Se accumulations in the muscle and liver tissue displayed a positive linear relationship with dietary Se levels. Se deficiency was apparent in fish fed the control diet and displayed reduced growth and feed efficiency. Red blood cell (RBC) counts were significantly (P

The immune responses and protection efficacy of a vaccine containing inactivated formalin-killed Photobacterium damselae subsp. piscicida formulated with alum and different unmethylated Cytosine phosphorothioate Guanine oligodeoxynucleotides (CpG-ODN, including 2006, 2395, 1668, and control ODN 2137) as the adjuvant were investigated in cobia Rachycentron canadum. Results showed that, formulation with CpG-ODN 1668 significantly (P

Tumor necrosis factor-alpha (TNF-α) and interleukin-8 (IL-8/CXCL8) play pivotal roles in mediating inflammatory responses to invading pathogens. In this study, we identified and analyzed expressions of cobia TNF-α and IL-8 during Streptococcus dysgalactiae infection. The cloned cDNA transcript of cobia TNF-α comprised of 1281 base pairs (bp), with a 774 bp open reading frame (ORF) encoding 257 amino acids. The deduced amino acid sequence of cobia TNF-α showed a close relationship (84% similarity) with TNF-α of yellowtail amberjack. The cloned IL-8 cDNA sequence was 828 bp long, including a 300-bp ORF encoding 99 amino acids. The deduced amino acid sequence of cobia IL-8 shared 90% identity with IL-8 of striped trumpeter. Cobia challenged with a virulent S. dysgalactiae strain displayed an early significant up-regulation of TNF-α and IL-8 in head kidney, liver, and spleen. Notably, IL-8 expression level increased dramatically in the liver at the severe stage of infection (72 h). In conclusion, a better understanding of TNF-α and IL-8 allows more detailed investigation of immune responses in cobia and furthers study on controlling the infectious disease caused by S. dysgalactiae.

The co-receptor CD4 plays an important role in distinguishing between helper T-cell (Th) and cytotoxic T lymphocyte (CTL). In the present study, we investigated the molecular features of CD4-2 cDNA to facilitate understanding of their roles in cobia (Rachycentron canadum). Two CD4-2 molecules have been identified and exhibited 16.10% amino acids identity with each other. The cDNA of CD4-2A consists of a 993 bp ORF encoding 330 aa with long intracytoplasmic tail containing conserved protein tyrosine kinase p56Lck binding (C-X-C) motif, a transmembrane region, and two extracellular Ig-like (Ig-like) domains are predicted. Comparatively, the cDNA of cobia CD4-2B consists of a 990 bp ORF encoding 329 aa without a transmembrane domain as well as C-X-C motif, and three Ig-like domains are present. Homology comparison showed that the CD4-2A aa sequence of cobia showed high similarity and similar structural features to CD4-2 from other species, while the deduced CD4-2B protein shares higher structural similarity to CD4-1 group. Phylogenetic analysis indicated that cobia CD4-2A was closer with CD4-2 molecules in other fish species, distant from the clade formed by fish CD4-1 and mammalian CD4 sequences. However, cobia CD4-2B grouped with other known teleost CD4-1 sequences. The expression pattern of CD4-2A and CD4-2B mRNA during the embryonic development followed the trend of an initial increase after fertilized, providing evidence of maternal transfer of CD4-2 homologues to the developing cobia embryos and larvae. All of these results are useful for better understanding of cell-mediated immunity of cobia.

Made available in DSpace on 2019-10-04T12:40:28Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-09-15 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) An 8-week nutritional experiment was conducted with the aim of evaluating the influences of different arachidonic acid (ARA) levels and two different temperatures (29.5 degrees C and 26.5 degrees C) on the growth performance, tissue and whole-body fatty acid (FA) compositions, plasma prostaglandin concentration, liver morphology and expression of genes related to lipid metabolism in cobia juveniles. A basal fat-reduced diet was manufactured and subsequently coated with different FA sources, distinct levels of ARA (ARA1, 0.5%; ARA2, 1.2%; and ARA3, 1.9%) and fish oil (FO: 8.8%, as a control diet). All diets were formulated to be isoproteic and isolipidic. Cobia juveniles (5.86 +/- 0.40 g) were randomly divided into 24 tanks with 18 animals each. Twelve tanks were kept at 29.5 degrees C, and 12 tanks were kept at 26.5 degrees C. The animals were fed twice per day with each experimental diet until apparent satiation in triplicate tanks at both temperatures. The results revealed that the animals maintained at 26.5 degrees C and fed with the ARA diets exhibited better growth than those fed with the FO diet and kept at 29.5 degrees C. In contrast to observations in other teleost species, ARA excess did not reduce growth or survival. The FA compositions of the livers, fillets and whole bodies generally reflected the diet compositions, i.e., gradual increases in ARA were observed according to the diet level. Additionally, greater depositions of docosahexaenoic acid (DHA) in the fillets of the animals from the ARA2 group that was kept at 26.5 degrees C were observed. The plasma prostaglandin levels were greater in the animals that were kept at 29.5 degrees C for all experimental diets and in the ARA2 animals compared with the FO groups at both temperatures. The FAS and SREBP-1 expressions in the livers were down-regulated in the ARA1 and ARA2 animals that were maintained at 26.5 degrees C compared with the animals that were fed the same diets but kept at 29.5 degrees C. Additionally, SREBP-1 expression was up-regulated in the ARA2 animals compared with the FO animals at both temperatures. The results of this study indicated that ARA inclusion between 0.5 and 1.9% combined with a temperature of 26.5 degrees C can improve juvenile cobia growth performance and directly influence the modulation of prostaglandin synthesis and the relative expressions of lipid genes. Univ Mogi das Cruzes, Nucl Integrado Biotecnol, Av Dr Candido Xavier de Almeida Souza 200, BR-08780911 Mogi Das Cruzes, SP, Brazil Univ Sao Paulo CEBIMar USP, Ctr Biol Marinha, Rodovia Manoel Hipolito Rego Km 131,5, BR-11600000 Sao Sebastiao, SP, Brazil CSIRO, Agr & Food, Aquaculture Program, Bribie Isl Res Ctr, Woorim, Qld 4507, Australia Univ Estadual Paulista Julio de Mesquita Filho CA, Ctr Aquicultura, Via Acesso Prof Paulo Donato Castellane S-N, BR-14884900 Jaboticabal, SP, Brazil Univ Sao Paulo, Inst Biociencias, Dept Fisiol, Rua Matao,Trav 14,321, BR-05508090 Sao Paulo, SP, Brazil Univ Estadual Paulista Julio de Mesquita Filho CA, Ctr Aquicultura, Via Acesso Prof Paulo Donato Castellane S-N, BR-14884900 Jaboticabal, SP, Brazil FAPESP: 2014/16320-7 FAPESP: 2016/12435-0

Gelatin is one type of protein obtained from partial hydrolysis of natural collagen. Utilization of gelatin has been widely applied to food, especially in foods related to elastic texture, for example marshmallow. The purpose of this research was to determine the quality of various types of gelatin based on gel strength, elsticity, water content, hedonic and to know the best marshmallow. The experimental design was complete randomized design. The treatment was different fish skin gelatin, namely patin, payus, and cobia with concentration of 7.39%. The parameters consisted of gelatin tests (yield, gel strength, viscosity) and marshmallow tests (gel strength, elasticity, water content and hedonic). Parametric data were analyzed with Analysis of Varience test and continued with Honestly Significant Difference test. The results showed that the use of different skin had significantly different (P

Streptococcus dysgalactiae is an important pathogenic bacterium that has caused economic loss for the cobia industry in Taiwan, ROC. This study presents a highly effective subunit vaccine composed of a moonlight protein, α-enolase, for the prevention of S. dysgalactiae infection. First, α-enolase was cloned, transformed, and expressed in E. coli for production of recombinant protein. Then, the protective efficacies of α-enolase recombinant protein were evaluated in combination with either a pro-inflammatory cytokine, TNF-α, or an oil adjuvant, ISA 763 AVG. The results showed that the combination of α-enolase and ISA 763 AVG was highly protective (RPS = 88.89%), while a negative effect was found in the group immunised with α-enolase adjuvanted with TNF-α (RPS = 22.22%). A further study was conducted with double dose of ISA 763 AVG, which led to an increased RPS value of 97.37%. Moreover, immunised cobia exhibited significantly greater lysozyme activity, antibody responses, and expression of certain immune-related genes post-challenge. Altogether, our results demonstrated that a combination of α-enolase recombinant protein with ISA 763 AVG adjuvant is a promising vaccine that can be employed for protection of cobia against S. dysgalactiae infection.

This research focuses on cobia skin hydrolysates and their antihypertensive effects via the inhibitory activities of angiotensin I-converting enzyme (ACE). Marine fish Cobia (Rachycentron canadum) skin was hydrolysed for 5 h using Protamex and Protease N to obtain the cobia skin protein hydrolysates PX-5 and PN-5, respectively. The soluble protein and peptide contents of the PX-5 were 612 and 270 mg/g, respectively, and for the PN-5, 531 and 400 mg/g, respectively. The IC50 of PX-5 and PN-5 on ACE was 0.221 and 0.291 mg/mL, respectively. Increasing the IC50 from 0.221 to 0.044 mg/mL by simulated gastrointestinal digestion (PX-5G) reduced the ACE-inhibitory capacity of PX-5. Using gel filtration chromatography, the PX-5G was fractioned into eight fractions. The molecular weight of the fifth fraction from PX-5G was between 630 and 450 Da, and the highest inhibitory efficiency ratio on ACE was 1552.4%/mg/mL. We identified four peptide sequences: Trp-Ala-Ala, Ala-Trp-Trp, Ile-Trp-Trp, and Trp-Leu, with IC50 values for ACE of 118.50, 9.40, 0.51, and 26.80 &mu, M, respectively. At a dose of 600 mg PX-5 powder/kg body weight, in spontaneously hypertensive rats PX-5&rsquo, s antihypertensive effect significantly reduced systolic and diastolic blood pressure by 21.9 and 15.5 mm Hg, respectively, after 4 h of oral gavage.

This experiment was conducted to study the effect of various dietary alanyl-glutamine dipeptide (AGD) and/or vitamin E (VE) supplement(s) on the expression of glutathione peroxidase (GPx) and peroxisome proliferator-activated receptor α (PPARα) genes, antioxidation, feed utilization, growth, and composition of juvenile cobia (Rachycentron canadum). Six groups of the juveniles in triplicate were fed for 12 weeks using 6 diets: Control diet (D0) contained only basic ingredients; Diet 1 (D1) contained single added AGD 10 g kg− 1 dried feed; Diet 2 (D2) contained single added VE 100 IU kg− 1 dried feed; Diet 3 (D3) contained added AGD 10 g kg− 1 dried feed and VE 100 IU kg− 1 dried feed; Diet 4 (D4) contained added AGD 5 g kg− 1 dried feed and VE 50 IU kg− 1 dried feed; Diet 5 (D5) contained added AGD 2.5 g kg− 1 dried feed and VE 25 IU kg− 1 dried feed. The juveniles were sampled randomly for analysis in week 0 and week 12. The main results were as follows: the diets with combined AGD and VE supplements could considerably promote feed utilization, growth, and improve composition of the juveniles; the combined AGD and VE supplements could significantly promote (P

The present study was carried out to understand the combined effect of O2 scavenger (OS) and antimicrobial film (AM) in extending the shelf life of fresh cobia (Rachycentron canadum) fish steaks stored at 2 °C in a plastic pouch of multilayer film of ethylene–vinyl alcohol. The chitosan based film containing ginger essential oil as an active antimicrobial agent was used as primary wrap for fish steaks. During storage, a significant (p < 0.05) reduction in the rate of total volatile base nitrogen formation and lipid oxidation as indicated by thiobarbituric acid value was observed for fish steaks wrapped with antimicrobial film and packed with O2 scavenger (OSAM). There was a lag phase of 5 days observed for total mesophilic count of OSAM compared to control sample. The limit of 7 log cfu g−1 of total mesophilic count was exceeded by control sample on 15th day of storage. OS application significantly reduced the growth of aerobic Pseudomonas spp. and AM film showed good inhibition against lactic acid bacteria and Brochothrix thermosphacta. Sensorily, the OSAM cobia steaks was acceptable up to 30 days compared to 15 days for samples in the control pouch.

Cobia is a fish cultivated worldwide and there are few studies on the potential of their waste, such as the liver, it's rich in oil and active compounds. The objective of this study was to extract cobia liver oil (CLO) using supercritical CO2 under moderate temperature conditions (50, 60 and 70 °C, 250 bar) and characterize the oil (physico-chemical analysis, fatty acids profile and squalene content). The results showed that CLO is rich in MUFA and presented squalene, suggesting that this matrix can be applied in the production of high nutritional value oil.

This study investigated the effects of orally administered Plantago asiatica , Houttuynia cordata , and Mentha haplocalyx on the growth and nonspecific immune responses of cobia ( Rachycentron canadum ). The nonspecific immune parameters assessed were weight gain, feed conversion ratio, superoxide anion (O 2 − ) production, superoxide dismutase (SOD) activity, phagocytic rate, phagocytic index, lysozyme activity, serum albumin and globulin, and albumin:globulin (A/G) ratio. The growth experiment indicated that 6-week dietary treatments did not significantly affect on the growth of cobia. Nonspecific immune responses showed that O 2 − production, SOD and lysozyme activity, and phagocytosis were significantly increased after the oral administration of P. asiatica and H. cordata , and the serum albumin:globulin ratio (A/G) gradually decreased. In this study, treatment of the Mentha haplocalyx on the cobia didn't present with the inducing of the phagocytosis ability compared with the treatment of P. asiatica and H. cordata. We suggest that oral administration of the 10 g/kg or 20 g/kg of the P. asiatica and H. cordata is exactly inducing the phagocytosis, ROS production, lysozyme activity and SOD production in the cobia.

The apparent digestibility coefficients (ADCs) of crude protein, lipid, phosphorous, and amino acids, as well as energy, of 13 animal feedstuffs were determined for cobia, Rachycentron canadum (initial weight 130.0 g). The feedstuffs tested included five types of fishmeal, two of blood meal, one of poultry meat meal, two of meat-and-bone meal, two of feather meal, and one type of shrimp meal. A reference diet was formulated and the test diets contained 70% of the reference diet and 30% of each feedstuff. The ADCs of crude protein, lipid, energy, phosphorous, and amino acids of the test ingredients ranged from 68.97 to 92.5%, 69.3 to 95.7%, 77.5 to 98.3%, 58.2 to 80.1%, and 72.5 to 97.0%, respectively. The ADCs of crude protein of white fishmeal, steam-dried brown fishmeal, imported flame-dried fishmeal, spray-dried blood cells, poultry byproduct meal, meat-bone meal, and meat meal were significantly higher than those of dried blood meal, fermented feather meal, and hydrolyzed feather meal (P

Aquaculture pens with brass mesh were installed at commercial fish farms in two locations, Panama and Mexico. Measurements of copper and zinc levels in the water and sediments were monitored over 468 and 435 days for the Panama and Mexico sites respectively. Additional chemical parameters were also measured including dissolved organic carbon in the water column and total solids, total organic carbon, total sulfides, redox potential and acid volatile sulfides and simultaneously extracted metals in the sediments. Measurements were taken at a reference site 1000 m away from the pens perpendicular to the dominant current direction, as well as 50 m upstream, 50 m downstream and adjacent to the pens. Muscle, skin and liver samples were taken from cobia (Rachycentron canadum) produced at the Panama site and analyzed for copper content. The dissolved copper levels at both farms stayed below 1 μg/L at all times. There was no significant difference in the dissolved copper levels between the reference site and other measurement sites at either location. There was also no observable increase in dissolved copper levels over time at the Mexico location although there was a significant difference in dissolved copper levels between the sampling days at the Panama location. Zinc concentrations also remained within safe levels, never exceeding 0.82 μg/L at any point. Copper and zinc levels in the sediments did not show a significant increase over time. The copper levels in tissue samples from the muscle tissue of the cobia raised in a brass mesh pen at the Panama site were 19% higher than those raised in the plastic mesh pen. The elevated copper levels are well below recommended daily intake levels and do not pose a risk to human health. There was no significant difference in copper levels of the skin or liver tissue samples. The absence of any increase in liver copper levels suggests that the fish's physiology and welfare are not impacted by brass mesh. The findings suggest that brass mesh is environmentally compatible with high energy marine environments and a commercially viable product for open ocean aquaculture farms.

Fish quality is conditioned by several factors, among them desensitization methods applied for fish managing and slaughtering. This research used electric shock at different intensities as a desensitization method for cobia (Rachycentron canadum) slaughtering and evaluated its effects over fish quality during refrigerated storage. The experiment was carried out by numbing the fish with electroshock at the intensities of 100, 150 and 200 Volts, and keeping them in refrigerated storage for 21 days. On the cobia, obtained from a commercial fish farm the following physical, chemical and sensorial characteristics as quality variables were evaluated: dielectric properties, rigor index, pH, texture, color, sensorial evaluation of freshness, ATP and degradation catabolites. The experimental design was a 6×3 factorial (6 times of analysis and 3 electroshock intensities). Significant differences (P

Despite being a carnivorous fish species, cobia (Rachycentron canadum) can utilize high levels of dietary carbohydrate (up to 360 g kg−1). By contrast, rainbow trout (also carnivorous) cannot, due to the absence of molecular induction of glycolytic enzyme and inhibition of gluconeogenic enzyme gene expressions such as pyruvate kinase (PK) and phosphoenolpyruvate carboxykinase (PEPCK). We hypothesized that this phenomenon is species-specific and will not be observed in cobia. Our results show that, at the molecular level, the mRNA abundance of the important glycolytic (PK) and gluconeogenic (PEPCK) enzymes in cobia liver are regulated by dietary carbohydrate-to-lipid (CHO:L) ratios and nutritional status (fed, unfed, and refed). Significantly upregulated hepatic PK and depressed PEPCK gene expressions were observed when the fish were fed with an increasing CHO/L-ratio diet or were refed. However, in contrast to gene expression, there was no significant effect of dietary CHO/L ratios on PK enzyme activity. The decrease in PEPCK activity was significantly found between low CHO/L ratio and high CHO/L ratio diets, whereas the moderate CHO/L ratio group showed intermediate values. But PEPCK activity appeared to be independent of nutritional status. These results suggest that nutritional regulation is obvious, at least at the molecular level, in the key hepatic enzymes (PK and PEPCK) of the glucose metabolism pathway, in response to different dietary CHO/L ratios and to the transition from being starved to fed. Determining whether other key enzymes involved in hepatic glucose metabolism contribute to glucose tolerance in cobia is necessary for further investigation of this phenomenon at the enzymatic and molecular levels.

The objective of this research was to compare the quality attributes of seasoned cobia sticks packed under vacuum and using modified atmosphere packaging (MAP) and stored under refrigeration, as well as to establish the most suitable gas mixtures to maintain product freshness and provide an extended shelf life. The seasoned cobia sticks were breaded with a mixture of dehydrated spices (parsley, onion, garlic, tomato and bacon), packaged under vacuum; 100% aerobic package (control, with the presence of atmosphere air); MAP1 (15% N2 + 80% CO2 + 5% O2), and MAP2 (20% N2 + 70% CO2 + 10% O2 ), and stored at 5°C for 28 days. Samples were taken every 72 hours for the microbiological analyses (total mesophilic count, total psychrotrophic count, coagulase positive Staphylococcus, Salmonella sp., and thermotolerant Coliforms at 45°C) and physicochemical analyses (pH, the nitrogen from the total volatile bases, and trimethylamine), all carried out in triplicate. The results showed that the seasoned cobia sticks remained safe and with good microbiological, physical and chemical quality for a longer period when packed in a modified atmosphere. MAP1 (15% N2 + 80% CO2 + 5% O2) was the system showing the best performance in the maintenance of quality and freshness, demonstrating the feasibility of ensuring quality and a longer shelf life (28 days) at 5°C.

This study investigated the effect of dietary methionine level on growth and lipid metabolism via the general control nonderepressible2 kinase (GCN2) pathway in cobia (Rachycentron canadum). Cobia were fed diets with six levels of methionine (0.62%, 0.84%, 1.02%, 1.15%, 1.25% and 1.42% of dry diet) with a constant cystine level (0.42% dry diet). The feeding experiment began in September 2013 and ended in December 2013; during the experiment, cobia were fed ad libitum twice daily (7:00 and 18:00 h) for 10 weeks. Cobia fed the diet with 1.02% methionine showed elevated weight gain (WG) and feed efficiency ratio (FER) compared with those fed the other diets (P

Photobacterium damselae subsp. piscicida (Phdp) is a major pathogen of cultured cobia (Rachycentron canadum), a primary target species for offshore cage culture in Taiwan. Serum antibody titers as well as efficiency and duration of protection against Phdp were evaluated following intraperitoneal administration of a candidate vaccine prepared with formalin-inactivated whole cells in combination with levan/alum adjuvants. The results showed vaccinates delayed the disease onset and had significantly (P

The aim of this study was to evaluate the influence of stunning/slaughter methods on the animal welfare aspects and on the physical and chemical parameters of frozen cobia ( Rachycentron canadum ) meat, during the frozen storage. Fish (n = 30 per treatment) were stunned electronarcosis, by hypothermia and CO 2 narcosis, then slaughtered by gill cutting and stored at − 18 °C for 180 days. During stunning/slaughter, water quality and the time to reach clinical indicators of unconsciousness were observed. During the storage period, every 60 days, samples were taken and analysed for pH, total volatile base nitrogen (TVBN), thiobarbituric acid reactive substances (TBARS), protein (actin and myosin) denaturation, fatty acid composition, colour (L*, a*, and b*), texture, drip loss (DL), cooking loss (CL) and water holding capacity (WHC). The time to reach unconsciousness resulted faster (2 s) when electronarcosis was applied, while the times were longer with hypothermia and CO 2 narcosis (17.5 min and 48 min, respectively). TVBN, DL, TBARS, texture, actin, myosin, pH, L*, a*, and b* were not affected by the stunning methods while CL was significantly higher in fillet of fish stunned by electronarcosis not altering the shelf life of the fillets. Based on the behaviour of the parameters analysed, electronarcosis seemed to be an adequate stunning method for cobia, since promoted fast unconsciousness and it did not compromise flesh quality.

This study determined impacts of dietary methionine concentrations at two temperatures on growth, feeding efficiency and N‐metabolites in juvenile cobia. Methionine concentrations of the experimental diets were deficient (M9; 9 g/kg), sufficient (M12; 12 g/kg) and surplus (M16, 16 g/kg). Water temperature was normal (30°C) or elevated (34°C). Twenty cobia in triplicate tanks were fed the experimental diets for 6 weeks. Both methionine and temperature affected cobia's growth and feeding efficiency. Cobia fed M9 performed lower than the fish fed M12 and M16 diets. Additionally, cobia reared at 34°C performed poorer than at 30°C, probably due to lower voluntary feed intake in the fish reared at 34°C. Protein efficiency ratio and protein productive value in cobia fed M9 diet were less than M12 or M16 diets. This was confirmed with the improved retentions of indispensable amino acids (AAs). No interactions between methionine and temperature were observed in growth and protein accretion. At 30°C, CF improved, while HSI and VSI declined upon methionine supplementation levels. Of which an interaction between temperature and methionine was present. Plasma, muscle and liver free AA and N‐metabolites were affected by methionine and temperature. Furthermore, temperature affected cobia's lipid class composition, resulting in increased phospholipids and cholesterol at 34°C., The project WISEFEED received funding by the European Union's H2020 Programme (Marie Skłodowska‐Curie grant No 691150) and additional funding from MINECO Spain project EFISHDIGEST AGL2014‐52888 and the European Social Fund FCT IF/00482/2014/CP1217/CT0005. S.E. acknowledges a Foundation for Science and Technology of Portugal (FCT) investigator grant IF/00482/2014/CP1217/CT0005 funded by the European Social Fund, the Operational Programme Human Potential and FCT. This work also received National Funds through FCT through project CCMAR/Multi/04326/2013 and Norwegian Agency for Development Cooperation NORHED, No. QZA‐0485 SRV‐13/0010.

The experiment was to study the effect of different dietary vitamin E (VE) and/or citric acid (CA) supplementation on the peroxisome proliferator-activated receptor α (PPARα) and aconitase (ACO) gene expression, fatty acids, antioxidant enzyme activities, and growth of juvenile cobia (Rachycentron canadum). Seven groups of cobia juveniles in triplicate were cultured in tanks using filtered and aerated seawater. The juveniles were fed twice a day using 7 specific diets: control diet (D0) without supplementation; Diets 1 to 6 (D1 to D6) were supplemented with CA 0, 12, 12, 6, 3, 1.5 g and VE 100, 0, 100, 75, 50, 25 IU per kg of dried feed, respectively. The juveniles were fed for 12 weeks and their liver, muscle, and serum were sampled randomly for analysis in weeks 0 and 12. The results showed that the supplementation of VE plus CA could significantly promote the relative mRNA expression of ACO and PPARα genes, concentration of polyunsaturated fatty acids (PUFAs), activity of antioxidant enzymes, and growth of juvenile cobia. The effect of both dietary VE plus CA supplementation on the above indexes was significantly greater (P

This study aimed to determine the effects of 2–5 wash cycles and the addition of tetrasodium pyrophosphate (TSPP) (0 %, 0.05 Surimi% and 0.1 % w/w)—with or without the addition of 0.4 % calcium chloride (CaCl2)—on the physical properties such as texture, colour, expressible moisture and microstructure of Cobia (Rachycentron canadum) surimi gel. The highest breaking force (484.85 g) was obtained with the addition 0.1 % TSPP alone on the fifth wash. However, a combination of 0.1 and 0.4 % CaCl2 in surimi gels at wash cycle 5 resulted in the highest degree of whiteness (86.8 %), as well as total expressible moisture (2.785 %) and deformation (17.11 mm). The highest surimi gel strength (6,923 g.mm) was obtained after three wash cycles with the addition of 0.1 % TSPP +0.4 % CaCl2. The physical properties of Cobia fish surimi gels were affected by the number of wash cycles and treatments with TSPP and CaCl2.

Five isonitrogenous and isocaloric diets were fed to juvenile cobia, to assess the relative contribution of different proteins (fish meal, soybean meal, corn gluten and beer yeast) to the growth of cobia. The dietary effects on nitrogen and carbon turnover and on the isotopic diet-consumer discrimination factors (Δ15N and Δ13C) were also assessed. Growth results showed that the final body weight, growth rate, feed conversion ratio and protein efficiency ratio of cobia fed diets with alternative protein were significantly lower (P

This study was conducted to compare the effects of manganese sulphate (Mn-S), glycine manganese(Mn-Gly) and manganese 2-hydroxy-4-(methylthio)butyrate (Mn-HMB) on juvenile cobia, Rachycentron canadum L. Treatments consisted of 0, 2, 4, 8, 16 or 32 mg supplemental Mn kg−1 from Mn-S, Mn-Gly or Mn-MHB. Growth performance, manganese status, antioxidant activities and tissue mineral content were analysed after a 70-day feeding period. Specific growth rate (SGR) increased with feeding 6.29 to 12.65 mg Mn kg−1 diet from the Mn-S or 6.86 to 12.39 mg Mn kg−1 from the Mn-Gly or 6.50 to 8.33 mg Mn kg−1 from the Mn-HMB and then plateaued above these levels. Feed conversion ratio (FCR) show decreasing first and then increased trend. Survival rate (SR) were not affected by the dietary treatments (P > 0.05). Fish fed diets supplemented with manganese at levels of 4–32 mg Mn kg−1 had obviously higher hepatic Mn-SOD activity (P

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

Limited availability and high prices underscore the need to use fish oil more judiciously in aquafeeds. Most alternative lipids contain little to no n-3 long-chain (LC) polyunsaturated fatty acids (PUFAs). If alternative lipids are fed exclusively, growth performance may be impaired and tissue fatty acid composition may be altered in fish such as the Cobia Rachycentron canadum. Alternative lipids that are rich in saturated fatty acids (SFAs) and monounsaturated fatty acids (MUFAs) may increase the efficiency of LC-PUFA metabolism and may limit or attenuate the tissue LC-PUFA loss associated with fish oil sparing. Cobias (weight [mean ± SE] = 77.4 ± 0.2 g) were fed diets containing either fish oil (control) or a 50/50 blend of fish oil and standard soybean oil, partially hydrogenated soybean oil, fully hydrogenated soybean oil, pork lard, or beef tallow. After 8 weeks, the feed conversion ratio (mean ± SE = 1.56 ± 0.04), weight gain (180 ± 6%), and specific growth rate (1.83 ± 0.04% of body weight/...

Replacement of long-chain (LC) polyunsaturated fatty acid (PUFA)-rich fish oil with alternative lipids in aquafeeds typically reduces the LC-PUFA content and associated nutritional value of farmed fish even if production performance is unaffected. Finishing can be used to augment tissue LC-PUFA levels prior to harvest; however, the effectiveness of this strategy for use with the Cobia Rachycentron canadum is relatively unknown. For 8 weeks, Cobias (initial weight [mean ± SE] = 59.8 ± 0.2 g) were fed diets in which the supplemental lipid consisted of 100% fish oil; 100% beef tallow; a blend of 33% beef tallow and 67% fish oil; or a blend of 67% beef tallow and 33% fish oil. After the 8-week grow-out period, all treatment groups received the 100% fish oil feed for 6 weeks to simulate finishing. Differences in production performance were observed, but growth and growth efficiency were not reduced by inclusion of beef tallow in the grow-out feeds. Prior to the finishing period, fatty acid profiles of ...

Taurine, which has multiple important physiological roles in teleost fish and mammals, is an amino acid not found in alternative protein sources not derived from animals. Although taurine is found in fish-meal-based feeds, its high water solubility leads to lower taurine levels in reduction-process-based feeds, which marine carnivores such as Cobia Rachycentron canadum are adapted to in their natural diets. Graded taurine supplementation (0, 0.5, 1.5, and 5.0%) added to a traditional fish-meal-based formulation was examined in two growth trials with Cobia: one initiated with 10-g individuals and the second initiated with 120-g individuals. During the first trial, in which growth as weight gain ranged from 123 to 139 g per fish, there was an increase in dietary taurine and a decrease in the feed conversion ratio from 1.04 to 0.99. During the second trial, in which growth ranged from 227 to 313 g gained per fish, there was no significant difference in performance characteristics between dietary trea...

The combined effects of hydrolysis time, temperature, pH, and ratio of enzyme to substrate on the degree of hydrolysis (DH) of cobia frame were determined using Response Surface Methodology. The effects of these factors were employed using a three-level factors face-centered central composite design. The proximate compositions of cobia frame and cobia hydrolysate powder were determined as well. The generated model equation gave a quadratic fit with experimental data. It is suggested that hydrolysis conditions for obtaining the optimum DH using Alcalase® were: temperature of 58°C, hydrolysis time of 134 min, pH of substrate at 9.4, and an enzyme concentration of 8.3%. Proximate analyses revealed that cobia frame contained 47.0% protein, 27.6% fat, and 24.8% ash; whereas cobia frame hydrolysate powder contained 88.8% protein, 0.58% fat, and 5.05% ash. The high protein content indicated that cobia frame hydrolysate is a potential ingredient for food and feed.