Showing papers in "Aquaculture Nutrition in 2005"
TL;DR: This review summarizes information regarding digestion and absorption of carbohydrates in cultivated fish and reports results of studies of digestive enzymes, e.g. amylase, chitinase, cellulase and brush border disaccharidases, which appear to be molecularly closely related and to have characteristics comparable to mammalian amylases.
Abstract: This review summarizes information regarding digestion and absorption of carbohydrates in cultivated fish Relevant results of studies of digestive enzymes, eg amylase, chitinase, cellulase and brush border disaccharidases are presented Fish amylases appear to be molecularly closely related and to have characteristics comparable to mammalian amylases Whether chitinases and cellulases are endogenous enzymes of some fish species is still a matter of speculation, although recent molecular evidence, at least for chitinase seems to settle the issue in favour of endogenous sources Feed and intestinal microbes may be the source of polysaccharidases in fish feeding on nutrients-containing non-starch polysaccharides Knowledge regarding monosaccharide transport in fish intestine as interpreted from studies of brush border membrane vesicles, everted sleeves of fish intestinal sections and molecular biology is discussed Glucose transporters of the intestinal brush border show characteristics similar to those found in mammals A tabulatory presentation of experimental details and results reported in the literature regarding starch digestibility is included as a basis for discussion Although numerous investigations on digestion of starch and other carbohydrates in fish have been published, the existing information is highly fragmentary As yet, it is impossible to derive a cohesive picture on the integrated process of carbohydrate hydrolysis and absorption and interaction with diet composition for any of the fish species under cultivation The physiological mechanisms behind the species differences are not known
542 citations
TL;DR: Grass carp is a fish with low energy requirement and excess dietary lipid level should be avoided, in conclusion.
Abstract: A study was undertaken to determine the effect of dietary lipid level on growth, feed efficiency and body chemical composition of juvenile grass carp. Seven isonitrogenous diets (400 g kg(-1) crude protein) containing seven dietary lipid level (0, 20, 40, 60, 80, 100 and 120 g kg(-1) dry matter) were fed to triplicate groups of 40 fish with initial weight 6.52 g, for 70 days. No obvious and assured essential fatty acid deficiency symptom appeared in fish fed the lipid-free diet. Excess dietary lipid level (100 and 120 g kg(-1)) resulted in decreased feed intake. The best growth performance and feed utilization was observed in fish fed 20-40 g kg(-1) dietary lipid. The fish fed a lipid-free diet had the lowest protein efficiency and protein retention. Growth performance and feed utilization increased with the increasing dietary lipid levels up to 40 g kg(-1) dietary lipid. Higher dietary level (above 40 g kg(-1)) made growth performance and feed utilization decrease and no protein sparing effect was observed. Lipid retention decreased as dietary lipid level increased. Mesenteric fat index (MFI) increased, hepatosomatic index (HSI) decreased with dietary lipid level. The increased MFI and simultaneous decrease lipid retention can be explained by differences in growth. The effect of dietary lipid levels on the chemical composition of tissues was significant only for whole body and muscle. The excess lipid content of liver in all groups was regarded as a slight symptom of fatty liver, which was partly identified by microscopic structural study and lower plasma lipid indexes, comparing to the initial plasma data. In conclusion, grass carp is a fish with low energy requirement and excess dietary lipid level should be avoided.
291 citations
TL;DR: The authors showed that vegetable oils such as RO, LO and OO can potentially be used as partial substitutes for dietary FO in European sea bass culture, during the grow out phase, without compromising growth rates but may alter some immune parameters.
Abstract: Triplicate groups of European sea bass (Dicentrarchus labrax L.), of initial weight 90 g, were fed four practical-type diets in which the added oil was 1000 g kg−1 fish oil (FO) (control diet), 600 g kg−1 rapeseed oil (RO) and 400 g kg−1 FO, 600 g kg−1 linseed oil (LO) and 400 g kg−1 FO, and 600 g kg−1 olive oil (OO) and 400 g kg−1 FO for 34 weeks. After sampling, the remaining fish were switched to the 1000 g kg−1 FO diet for a further 14 weeks. Fatty acid composition of flesh total lipid was influenced by dietary fatty acid input but specific fatty acids were selectively retained or utilized. There was selective deposition and retention of docosahexaenoic acid (DHA; 22:6n-3). Eicosapentaenoic acid (EPA; 20:5n-3) and DHA were significantly reduced and linolenic (LNA; 18:3n-3), linoleic (LA; 18:2n-6) and oleic (OA; 18:1n-9) acids significantly increased in flesh lipids following the inclusion of 600 g kg−1 RO, LO and OO in the diets. No significant differences were found among different treatments on plasma concentrations of prostaglandin E2 and prostaglandin F2α. Evaluation of non-specific immune function, showed that the number of circulating leucocytes was significantly affected (P < 0.001), as was macrophage respiratory burst activity (P < 0.006) in fish fed vegetable oil diets. Accumulation of large amounts of lipid droplets were observed within the hepatocytes in relation to decreased levels of dietary n-3 HUFA, although no signs of cellular necrosis was evident. After feeding a FO finishing diet for 14 weeks, DHA and total n-3 HUFA levels were restored to values in control fish although EPA remained 18% higher in control than in the other treatments. This study suggests that vegetable oils such as RO, LO and OO can potentially be used as partial substitutes for dietary FO in European sea bass culture, during the grow out phase, without compromising growth rates but may alter some immune parameters.
233 citations
TL;DR: Apparent digestibility of crude protein and the amino acids arginine, lysine, methionine and phenylalanine increased significantly with increased dietary inclusion of FPH, and Plasma free amino acids, ammonium and urea indicated that FPH amino acids was absorbed earlier and nonsynchronously, and may thus be more prone to be catabolized than in those fish fed the less solubilized protein.
Abstract: The present work was designed to study whether changes in dietary protein quality by means of partial inclusion of fish protein hydrolysate (FPH) would alter fish growth, feed utilization, protein retention and metabolism and fish health in general. FPH was produced after hydrolysing whole minced herring using the industrial enzyme Alcalase. The dietary protein source, low-temperature-dried (LT) fishmeal nitrogen was exchanged with FPH nitrogen at six levels of inclusion ranging from 0 to 300 g kg(-1). The experimental diets were fed to post-smolt (1+) Atlantic salmon (Salmo salar), with mean initial weight of 174 g for a period of 68 days. All diets were iso-nitrogenous, iso-energetic and contained the same amount of amino acids. Fish fed medium inclusion of FPH (180-240 g kg(-1)) showed a tendency to have higher feed intake than fish fed lower and higher levels of FPH inclusions. Significant higher individual specific growth rates were present in fish fed diets with 180 and 240 g kg(-1) FPH when compared with those fed 300 g kg(-1). Feed conversion ratio increased significantly (R2 = 0.61) and protein efficiency ratio decreased significantly (R2 = 0.59) in fish fed increased levels of FPH. Further, apparent digestibility of crude protein and the amino acids arginine, lysine, methionine and phenylalanine increased significantly with increased dietary inclusion of FPH. Plasma free amino acids, ammonium and urea indicated that FPH amino acids was absorbed earlier and nonsynchronously, and may thus be more prone to be catabolized than in those fish fed the less solubilized protein. FPH inclusion did not have an impact on fish health, as evaluated by haematology and clinical parameters.
183 citations
TL;DR: Dietary fish oil replacement had no effect on either hepatic lipid droplets accumulation or degree and pattern of vacuolization in the observed liver sections, suggesting that both sea bass and trout can be fed diets containing up to 50% soybean oil without adverse effects on tissue lipid composition or liver histology.
Abstract: Summary
A 12-week feeding trial was conducted to evaluate the effects of fish oil replacement by soybean oil, on lipid distribution and liver histology of two commercially important finfish species: rainbow trout (Oncorhynchus mykiss) and European sea bass (Dicentrarchus labrax). Sea bass (16.2 ± 0.5 g; mean ± SD) and rainbow trout (52.1 ± 0.5 g) juveniles were fed one of three isonitrogenous (500 g kg−1 CP) and isoenergetic (19 kJ g−1) diets, containing 0% (control, diet A), 25% (diet B) and 50% (diet C) soybean oil. At the end of the experiment, lipid deposition was evaluated in muscle, liver and viscera. Cholesterol and triglycerides levels were also determined in plasma. Tissue total, neutral and polar lipid composition (g kg−1 total lipids) showed no significant differences within species, regardless the dietary treatment. The same trend was observed for plasma parameters (P > 0.05). Viscera were the preferential tissue of lipid deposition, with 252–276 and 469–513 g kg−1 total lipid content in trout and sea bass, respectively. Dietary fish oil replacement had no effect on either hepatic lipid droplets accumulation or degree and pattern of vacuolization in the observed liver sections. These data suggest that both sea bass and trout can be fed diets containing up to 50% soybean oil without adverse effects on tissue lipid composition or liver histology.
169 citations
TL;DR: Results indicate that up to 400 g kg(-1) of fishmeal protein can be replaced by defatted soybean meal without causing significant reduction in growth, and feed conversion ratio and protein efficiency ratio were significantly affected.
Abstract: An 8-week feeding experiment was conducted in floating cages (1.5 x 1.0 x 2.0 m) to determine the potential use of defatted soybean meal (roasted and solvent-extracted) as a partial replacement of fishmeal in the isonitrogenous (approximately 450 g kg(-1) CP crude protein) diet for juvenile cobia with an initial average weight of about 8.3 g. Diets were formulated to include 0, 100, 200, 300, 400, 500 and 600 g kg(-1) (diets D0, D10, D20, D30, D40, D50 and D60, respectively) of fishmeal protein being substituted by defatted soybean meal without methionine supplementation. The results showed that weight gain rate decreased significantly when the replacement level of fishmeal protein was increased from 400 g kg(-1) to 500 g kg(-1), and the D60 diet was the lowest in all groups. These results indicate that up to 400 g kg(-1) of fishmeal protein can be replaced by defatted soybean meal without causing significant reduction in growth. Feed conversion ratio (FCR) and protein efficiency ratio (PER) were significantly affected by the replacement level of fishmeal protein being substituted by defatted soybean meal, when the replacement level of fishmeal protein was 200 g kg(-1) (diet, D20), FCR was the lowest and PER was the highest. There were no significant differences in the moisture, lipid, crude protein and ash content in whole body and muscle, while lipid content in liver increased as the dietary soybean meal replacement levels increased. There were significant differences in haemoglobin, haematocrit, red blood cell, plasma glucose and triglyceride concentration in fish fed diets with different soybean meal replacement levels. Results of this trial indicated that the optimum level of fishmeal protein replacement with defatted soybean meal, determined by quadratic regression analysis was 189.2 g kg(-1), on the basis of maximum weight gain.
152 citations
TL;DR: In this paper, a total of seven distinct feeding periods were studied that incorporated higher levels of dietary oil inclusion, and larger pellet size as fish size increased, and partial least square regression analyses identified feed concentration, growth rate and feed utilization, but not variations in lipid content, as factors significantly affecting fish PCDD/F and DLPCB levels.
Abstract: Atlantic salmon were fed extruded diets based on either 100% fish oil (FO) or 100% vegetable oil blend (VO) substitution for 22 months. A total of seven distinct feeding periods were studied that incorporated higher levels of dietary oil inclusion, and larger pellet size as fish size increased. Whole fish levels of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F) and dioxin-like PCBs (DLPCB) were analysed at the beginning and end of each of the seven feeding periods. The PCDD/F and DLPCB concentrations in the FO diets increased from 2.43 to 4.74 ng WHO-TEQ kg−1 (TEQ, toxic equivalents), while VO diets decreased from 1.07 to 0.33 WHO-TEQ kg−1 as oil inclusion increased. Partial least square regression analyses identified feed concentration, growth rate and feed utilization, but not variations in lipid content, as factors significantly affecting fish PCDD/F and DLPCB levels. Accumulation efficiencies for DLPCB (740 ± 90 g kg−1) were significantly (P < 0.01) higher than for PCDD/F (430 ± 60 g kg−1), explaining the increasing dominance of DLPCB levels over PCDD/F levels in whole fish (DLPCB : PCDD/F ratio of 2.4 ± 0.1 for both VO and FO fed fish) compared with feed (DLPCB : PCDD/F ratio of 1.5 and 0.34 for FO and VO feed respectively). Vegetable oil substitution significantly reduced the level of PCDD/F and DLPCB (eightfold and twelve-fold, respectively) in the fillet of a 2 kg salmon, but, also negatively affected beneficial health components such as fillet n-3/n-6 fatty acid ratio.
134 citations
TL;DR: It is suggested that CPO can be used at least to partially replace FO in diets for rainbow trout in terms of permitting similar growth and feed conversion, and having no major detrimental effects on lipid and fatty acid metabolism, although flesh fatty acid compositions are significantly affected at an inclusion level above 50%, with n-3HUFA reduced by up to 40%.
Abstract: This study aimed to investigate the effects of dietary crude palm oil (CPO) on fatty acid metabolism in liver and intestine of rainbow trout. Triplicate groups of rainbow trout for 10 weeks at 13 � C were fed on diets in which CPO replaced fish oil (FO) in a graded manner (0–100%). At the end of the trial, fatty acid compositions of flesh, liver and pyloric caeca were determined and highly unsaturated fatty acid (HUFA) synthesis and fatty acid oxidation were estimated in isolated hepatocytes and caecal enterocytes using [1- 14 C]18:3n-3 as substrate. Growth performance and feed efficiency were unaffected by dietary CPO. Fatty acid compositions of selected tissues reflected the dietary fatty acid composition with increasing CPO resulting in increased proportions of 18:1n-9 and 18:2n-6 and decreased proportions of n-3HUFA, 20:5n-3 and 22:6n-3. Palmitic acid, 16:0, was also increased in flesh and pyloric caeca, but not in liver. The capacity of HUFA synthesis from 18:3n-3 increased by up to threefold in both hepatocytes and enterocytes in response to graded increases in dietary CPO. In contrast, oxidation of 18:3n-3 was unaffected by dietary CPO in hepatocytes and reduced by high levels of dietary CPO in enterocytes. The results of this study suggest that CPO can be used at least to partially replace FO in diets for rainbow trout in terms of permitting similar growth and feed conversion, and having no major detrimental effects on lipid and fatty acid metabolism, although flesh fatty acid compositions are significantly affected at an inclusion level above 50%, with n-3HUFA reduced by up to 40%.
133 citations
TL;DR: Liver tissues of fish fed diets enriched with vegetable oils showed significantly increased lipid contents of 162 (LO) and 147 (SO) gkg-1 and indicate decreased lipid utilization compared with fish fed FO diet (liver lipid content 112 g kg-1).
Abstract: Pike perch (Sander lucioperca) has been identified as specie destined to diverse European inland aquaculture, but knowledge on the nutritional requirements is weak. Therefore, we investigated the effect of varying dietary fatty acid (FA) profile by partial replacement of fish oil (FO) with vegetable oils on growth, FA and body composition of juvenile pike perch. An extruded basal diet containing 59 g kg-1 crude lipids (FO) was added with 60 g kg-1 FO, 60 g kg-1 linseed oil (LO) or 60 g kg-1 soybean oil (SO). The resulting dietary FA composition differed mainly in the triglyceride fraction and was characterized by highest amounts of linolenic acid (18:3 n-3) in the LO diet and linoleic acid in the SO diet. Diet enriched with FO contained highest contents of highly unsaturated FA 20:5 n-3 (eicosapentaenic acid) and 22:6 n-3 (docosahexaenic acid). Pike perch were held in a recirculation system and each feeding group (in triplicate) was fed with experimental diets at a daily rate of 35 g kg-1 of biomass for 57 days by automatic feeders. Weight gain and specific growth rate of experimental feeding groups ranged between 18.47 and 19.58 g and 1.37-1.45% day-1 and was not affected by the dietary composition indicating that FO can be replaced by vegetable oils without negative impact on growth performance. In contrast to the whole body and muscle composition, liver tissue was affected by the varying diets. Liver tissues of fish fed diets enriched with vegetable oils showed significantly increased lipid contents of 162 (LO) and 147 (SO) g kg-1 and indicate decreased lipid utilization compared with fish fed FO diet (liver lipid content 112 g kg-1). Nevertheless, hepatosomatic index of pike perch was not influenced by dietary lipid composition. The FA profile of pike perch was generally determined by the dietary FAs.
113 citations
TL;DR: There was a tendency to an overall improvement of colour parameters in fish fed diets with high levels of C. vulgaris and astaxanthin, and the results indicated that the best temperature range to maximize skin pigmentation was 26–30 °C.
Abstract: The aim of this work was to investigate the effect of different carotenoid sources/concentrations and temperature on goldfish (Carassius auratus) skin pigmentation. In the first trial (trial A), the effect of carotenoid source (natural – microalgae Chlorella vulgaris and synthetic – Carophyll Pink) and carotenoid concentration (45, 80 and 120 mg pigment kg−1 diet) was tested. Six homogeneous duplicate groups of juvenile goldfish (7.4 g) were fed, for 5 weeks, one of the diets containing 45, 80 or 120 mg of total pigments of C. vulgaris biomass or synthetic astaxanthin per kg of diet (Cv45, Cv80, Cv120, Ax45, Ax80, Ax120), respectively. In trial B, the effect of water temperature on skin pigmentation was studied. Five homogeneous duplicate groups of 25 goldfish each (5.2 g) were fed diet Ax45 over 9 weeks, to test the following temperatures: 22, 24, 26, 28 and 30 °C. At the end of both trials, samples of skin along the dorsal fin were withdrawn for subsequent analysis of total carotenoid content, intensity of colour, red and yellow hue and visual observation. The best carotenoid concentrations were achieved with astaxanthin diets. There was a tendency to an overall improvement of colour parameters (L and b) in fish fed diets with high levels of C. vulgaris. The results indicated that the best temperature range to maximize skin pigmentation was 26–30 °C.
98 citations
TL;DR: In this article, the effect of dietary protein and lipid levels on growth and body composition of juvenile turbot was determined at optimum salinity and temperature conditions of 17g L−1 and 19.2°C, respectively.
Abstract: Effect of dietary protein and lipid levels on growth and body composition of juvenile turbot was determined at optimum salinity and temperature conditions of 17 g L−1 and 19.2 °C, respectively, by using 3 × 2 (protein levels: 550, 600 and 650 g kg−1; lipid levels: 69 and 168 g kg−1) factorial design with three replications of each. Fish were hand-fed to satiety twice daily throughout the feeding trial. Weight gain and specific growth rate of fish were significantly (P < 0.05) increased with increased dietary lipid level, but not by dietary protein level. Daily feed intake was significantly (P < 0.05) affected by both dietary protein and lipid levels. Feed efficiency ratio and protein efficiency ratio were significantly (P < 0.05) affected by dietary lipid level, but not by dietary protein level. Moisture content of whole body was significantly (P < 0.05) affected by dietary lipid level, but not by dietary protein level. Crude lipid content of whole body was significantly (P < 0.05) affected by dietary lipid level, but not by dietary protein level. Significantly higher 20:5n−3, 22:6n−3 and n−3 highly unsaturated fatty acids were observed in turbot fed the low lipid diet than fish fed the high lipid diet in all protein levels, but significantly lower 18:2n−6 was observed in fish fed the former compared with the latter. In considering results of growth, specific growth rate and efficiency of feed, optimum dietary protein and lipid levels for juvenile turbot seemed to be 550 and 168 g kg−1 of the diet, respectively, under optimum salinity and temperature conditions.
TL;DR: The study reveals that African catfish C. gariepinus performed best the diet containing 430 g kg−1, 21.2 kJ g−1 and 20.5 mg protein kJ g−1 GE protein, gross energy and P/E ratio, respectively.
Abstract: An 8-week feeding trial was conducted in a recycling water system at 28 ± 1 °C to investigate protein to energy ratio (P/E ratio) in African catfish Clarias gariepinus (10.9 ± 0.04 g). Six fishmeal-based diets of two protein levels (330 and 430 g kg−1), each with three lipid levels (40, 80 and 120 g kg−1) resulted in P/E ratios ranging from 15.5 to 21.3 mg protein kJ−1 gross energy (GE) were fed to 20 fish (per 30-L tank) in triplicate. Fish were fed 50 g kg−1 of their body weight per day adjusted fortnightly. Significantly higher (P 0.05) values of protein utilization were found in-between the both (higher and lower) protein diets. Higher lipid deposition (P 0.05). Digestive enzyme activities (protease and lipase) and histological examination of intestine and liver of fish fed varying P/E diets found no significant differences in response to experimental diets. The study reveals that African catfish C. gariepinus performed best the diet containing 430 g kg−1, 21.2 kJ g−1 and 20.5 mg protein kJ g−1 GE protein, gross energy and P/E ratio, respectively.
TL;DR: In practical feed formulations that contain significant amounts of terrestrial protein but relatively low levels of marine ingredients, there does not appear to be need for additional feeding effectors, and crustacean meal and krill meal do provide a significant nutritional benefit, as seen by the improved growth rates in this study.
Abstract: The inclusion in feed formulations of ingredients that act as attractants and feeding incitants or stimulants has been proposed as a means of increasing feed consumption, and hence growth, of farmed shrimp. Squid, crustacean and krill meals, fish and krill hydrolysates and a betaine product (Finnstim) were examined to assess their relative effectiveness in increasing the feed intake of black tiger shrimp Penaeus monodon. These presumed feeding effectors were added to a base feed at between 5 and 50 g kg−1. Given a choice between the base feed and one containing one of the test ingredients, P. monodon showed a significantly greater preference for the feeds containing crustacean or krill meal. Four of the presumed feeding effectors were further evaluated in a growth response experiment. There was no significant difference in the amount the shrimp consumed of any of the feeds. However, the growth rate of the shrimp was about 20% faster on the feeds containing crustacean meal or krill meal. Although ingredients such as crustacean meal or krill meal can improve feed intake, in practical feed formulations that contain significant amounts of terrestrial protein but relatively low levels of marine ingredients, there does not appear to be need for additional feeding effectors. However, crustacean meal and krill meal do provide a significant nutritional benefit, as seen by the improved growth rates in this study.
TL;DR: Regression analysis showed a negative effect of inclusion of Soybean, although fish fed diets containing 20% and 30% of soybean did not present statistical differences and grew significantly more, and had a better feed conversion ratio, than fish fed 40 or 50% diets.
Abstract: The availability of defatted soybean meal as a substitute for fish meal was evaluated in juvenile (450 g on average) yellowtail fed diets containing several levels of soybean meal (from 20 to 50%). After 153 days, liveweight averages were 980, 925, 795 and 670 g for fish fed diets in which fish meal was partially substituted with 20, 30, 40 and 50% soybean meal, and feed conversion ratios were 2.79, 3.09, 4.57 and 6.52, respectively. Regression analysis showed a negative effect of inclusion of soybean, although fish fed diets containing 20% and 30% of soybean did not present statistical differences and grew significantly more, and had a better feed conversion ratio, than fish fed 40 or 50% diets. Likewise, muscle protein level was lower and lipid content was higher in fish fed 20 or 30% soybean. No differences were obtained for protein digestibility coefficients of experimental diets.
TL;DR: The 3-week fasting generally improved the quality of fish without any body weight or filleting yield losses, thus indicating its possible use for end product improvement, however, another important observation was a white discoloration of the fish skin, which occurred during fasting.
Abstract: The aim of this study was to investigate the effects of fasting on certain quality parameters of commercial size gilthead sea bream (Sparus aurata) with different dietary history. Three dietary groups (× two replicates) were distributed into six sea cages and fed ad libitum by demand feeders for 4 months with feeds containing different protein–fat percentages (38 : 20, 45 : 15, 51 : 10). The fish were submitted to a subsequent fasting for 3 weeks. They all showed similar mobilization patterns with an initial hepatosomatic index reduction (indicating liver fat mobilization), followed by muscle fat reduction (from >90 g kg−1 to around 75 g kg−1) and a subsequent fat deposit reduction. The 3-week fasting generally improved the quality of fish without any body weight or filleting yield losses, thus indicating its possible use for end product improvement. However, another important observation was a white discoloration of the fish skin, which occurred during fasting.
TL;DR: Results suggest that C. quadricarinatus can modify hepatopancreatic enzyme levels in response to different compounds in the diet and can digest a broad variety of ingredients, particularly starch.
Abstract: A feeding trial was conducted to determine digestive enzyme activity in Cherax quadricarinatus in response to diet composition. Eight experimental diets, each containing one of squid, red crab, sardine (600 and 650 g kg )1 crude protein), sorghum, wheat meal, soy paste and the reference diet were evaluated over 30 days in terms of amylase, lipase, and protease activities in the hepatopancreas. The diet containing wheat meal produced the highest amylase activity. Lipase activity was not significantly different among treatments. Protease activity was higher in animals fed fish meal (60 g kg )1 protein), soy paste and reference diet. Results suggest that C. quadricarinatus can modify hepatopancreatic enzyme levels in response to different compounds in the diet and can digest a broad variety of ingredients, particularly starch.
TL;DR: Results indicated that a diet containing 270 g kg DP (equivalent to 320 g kg )1 CP), 75 g kg DL 1 with a DP/DE of 18.4 mg protein kJ )1 , and 0.031 g protein per animal per day was optimum for juvenile C. quadricarinatus under the tested experimental conditions.
Abstract: This study determined the effect of different dietary protein and lipid levels on growth and survival of juvenile redclaw Cherax quadricarinatus. Nine practical test diets were formulated to contain three crude protein (CP) levels [260, 310 and 360 g kg )1 , equivalent to 225, 260 and 296 g kg )1 digestible protein (DP) respectively] at three crude lipid (CL) levels (40, 80 and 120 g kg )1 , equivalent to 38, 67 and 103 digestible lipids respectively), with digestible protein : digestible energy (DP : DE) ranging from 14.6 to 22.6 mg protein kJ g )1 . Three replicate groups of 15 crayfish (initial weight mean ± SD, 0.71 ± 0.13 g) per diet treatment were stocked in 40 L tanks, at 28 � C for 60 days. The highest mean weight, specific growth rate and biomass, with values of 7.0 g, 3.67% day )1 , and 370.2 g m )2 , respectively, were achieved by feeding a diet with P : L ¼ 310 : 80 (P < 0.05). The treatments resulted in a survival rate of 80–91%, feed conversion ratio of 1.08–1.61 and protein efficiency ratio of 2.24–3.08. Results indicated that a diet containing 270 g kg )1 DP (equivalent to 320 g kg )1 CP), 75 g kg )1 DL 1 with a DP/DE of 18.4 mg protein kJ )1 , and 0.031 g protein per animal per day was optimum for juvenile C. quadricarinatus under the tested experimental conditions.
TL;DR: The results showed mean weight gain and feed conversion ratio were highest for diets containing 28.5 and 30.2 g DP MJ DE )1, whereas only slight differences in nitrogen retention efficiency were observed as discussed by the authors.
Abstract: Juvenile haddock, Melanogrammus aeglefinus L. (initial weight, 13.5 ± 0.1 g) were fed practical diets containing digestible protein to digestible energy (DP DE )1 ) ratios of 25– 30 g DP MJ DE )1 as-fed using three protein levels (450, 500 and 550 g kg )1 ) each at two lipid levels (110 and 160 g kg )1 ) for 63 days. The results showed mean weight gain and feed conversion ratio were highest for diets containing 28.5 and 30.2 g DP MJ DE )1 .D P DE )1 ratio had no significant effect on protein efficiency ratio except at the lowest level (24.7 g DP MJ DE )1 ) indicating a protein sparing effect of higher lipid when dietary protein is below the requirement. Haddock appears to preferentially use protein as the prime source of DE. DP DE )1 ratio had little effect on apparent digestibility (AD) of protein while AD of lipid was significantly affected. Significant differences in AD of energy and organic matter were found to be inversely related to the carbohydrate level of the diet. DP DE )1 ratios of 28.5 g DP MJ DE )1 or lower resulted in significantly higher hepatosomatic indexes. The highest whole-body nitrogen gains and energy retention efficiencies were achieved at 28.5 and 30.2 g DP MJ DE )1 , whereas only slight differences in nitrogen retention efficiencies were observed. The highest levels of energy retained in the form of protein were achieved at 28.5 and 30.2 g DP MJ DE )1 . The diet that provided the best growth, feed utilization and digestibility with minimal HSI contained 546 g kg )1 protein (513 g kg )1 DP), 114 g kg )1 lipid, 164 g kg )1 carbohydrate, 17.0 MJ kg DE )1 and a DP DE )1 ratio of 30.2 g DP MJ DE )1 .
TL;DR: This was a first indication that up to 130 g kg(-1) RR-soybean protein can safely be used in diets for Atlantic salmon, and there is still a need to elucidate higher inclusion levels of GM feed ingredients, and why spleen index was reduced, and if this was a long- or short-term effect.
Abstract: The present paper represents a part of a major scientific effort aiming to reveal possible effects, nutritional or health related, of genetically modified (GM) feed ingredients for Atlantic salmon. For 3 months groups of post-smolt Atlantic salmon were treated with diets holding 130 g kg1 of the protein as soybean, one which contained 800 g kg(-1) GM type RR (Roundup Ready), and compared with a standard counterpart (commercial hybrid, not isogenic line) analysed to be non-GM (nGM), and again compared with a standard fishmeal diet without soybean protein. All diets were composed to be within the category 'compositional equivalent' and held exactly the same proximate compositions, starch and sugar levels, above requirements for methionine and lysine, equal fatty acid profiles, vitamin, mineral and pigment contents. There was, however, a slight difference in levels of anti-nutrients between the three diets. The various dietary treatments resulted in more than tripling of fish weight in all groups. In addition no significant differences in feed utilization, whole body, liver and muscle proximate compositions, and no significant differences in muscle fatty acid profiles were measured. The diet without soybean of either type resulted in greater retention of lipid, but equal retention of protein (protein productive value). The relative sizes of liver, kidney, head-kidney and brain were the same in all dietary groups, while the relative size of the spleen showed significant differences between fish fed the genetically modified soy diet compared with fish fed the nGM soybeans. Fish fed the soy diets of either type also showed a somewhat reduced mean erythrocyte cell volume. All other haematological values were equal between diet groups. The detoxification system, measured as glutathione peroxidase (GPx) and lysozyme activities, showed equal values for all groups when measured in plasma and liver or head-kidney. The distal part of the intestine showed reduced sizes as an effect of soybean additions, without any differences between the GM and nGM type. Our results showed high growth, no mortality, haematological values within normal ranges, and efficient and equal responses in the detoxification system. This was a first indication that up to 130 g kg(-1) RR-soybean protein can safely be used in diets for Atlantic salmon. However, there is still a need to elucidate higher inclusion levels of GM feed ingredients, and why spleen index was reduced, and if this was a long- or short-term effect.
TL;DR: It is demonstrated that tropical spiny lobsters grow well when fed high-protein, high lipid, pelleted feeds, but feeding on a sole diet of freshly thawed green-lip mussels was unsatisfactory.
Abstract: In an 8-week growth experiment, juvenile spiny lobsters (Panulirus ornatus) grew best on a feed containing at least 610 g kg−1 crude protein on a dry matter basis (DM) and a digestible protein to digestible energy ratio of 29.8 mg kJ−1. The study entailed a six treatment by four replicate randomized block experiment with 222 wild-caught P. ornatus of mean initial weight (±SD) of 2.5 ± 0.19 g. The lobsters were fed one of five isolipidic feeds (approximately 130 g kg−1 DM) in which the crude protein was serially incremented between 330 and 610 g kg−1 DM, or a reference diet comprising the flesh of frozen green-lip mussels. Lobsters fed the pelleted feeds had high survival (79 ± 4.5%) and responded to increasing dietary crude protein content with progressively higher growth rates, with the daily growth coefficient improving from 0.72% day−1 with 330 g kg−1 crude protein to 1.38% day−1 with 610 g kg−1 crude protein. Both growth rate and survival were low with the mussel diet (0.80% day−1and 41 ± 4.5%, respectively). These results demonstrate that tropical spiny lobsters grow well when fed high-protein, high lipid, pelleted feeds, but feeding on a sole diet of freshly thawed green-lip mussels was unsatisfactory.
TL;DR: The results of this study suggest that the diet containing 460–510 g kg−1 protein with low lipid level (60 g-kg-1) is optimal for growth and efficient feed utilization of juvenile flounder.
Abstract: A 3 × 3 factorial experiment was conducted to determine proper levels of dietary protein, lipid and dextrin for juvenile flounder. Nine experimental diets were formulated to contain three protein levels (410, 460 and 510 g kg−1) and three lipid levels (60, 130 and 190 g kg−1) with corresponding dextrin levels (250, 150 and 50 g kg−1). Triplicate groups of fish (8.9 ± 0.4 g) were hand-fed the diets to apparent satiation for 7 weeks in flow-through system. Specific growth rate was the highest in fish fed the 510 g kg−1 protein diet with 60 g kg−1 lipid, and was not significantly different from that of fish fed 460 g kg−1 protein diet with 60 g kg−1 lipid. Feed efficiency ratio tended to increase as dietary protein level increased. The feed efficiency ratio of fish fed the 510 g kg−1 protein diets with 60–190 g kg−1 lipid levels was not significantly different from that of fish fed 460 g kg−1 protein diet with 60 g kg−1 lipid. Daily feed intake tended to decrease with increasing dietary lipid level at each protein level. Daily protein intake increased with increasing dietary protein level at 60 g kg−1 lipid level. Hepatosomatic index and visceralsomatic index increased with increasing dietary lipid level at each protein level. The lipid contents of liver, viscera and whole body, and concentrations of plasma total cholesterol and triglyceride increased with increasing dietary lipid levels; however, no significant difference was observed in the contents of dorsal muscle lipid. The results of this study suggest that the diet containing 460–510 g kg−1 protein with low lipid level (60 g kg−1) is optimal for growth and efficient feed utilization of juvenile flounder.
TL;DR: It is suggested that feeding channel catfish a diet containing 450 g kg(-1) non-heat-treated RSBM did not cause severe histologic changes associated with soybean meal anti-nutritional factors as have been reported in salmonids.
Abstract: The histopathologic effects of feeding heat-treated soybean meal to fingerling channel catfish (Ictalurus punctatus) were studied. Fish were fed one of six diets: a diet containing 450 g kg(-1) commercial soybean meal (CSBM), or diets with the CSBM replaced by non-heat-treated raw soybean meal (RSBM0), or RSBM heated at 130 degrees C for 5 min (RSBM5), 10 min (RSBM10), 20 min (RSBM20) or 40 min (RSBM40). After 10 weeks, tissue samples were taken from the stomach, proximal intestine, distal intestine, liver, pancreas and spleen from fish in each group for histologic examination. Mild necrotic lesions were found in the gastric glands, pancreas and liver of fish in all the groups (treatment and control groups). Hepatic glycogen deposition was also observed in all the groups, and the spleen samples exhibited considerable brownish-black pigment deposition around the splenic corpuscles and diffuse mild-to-moderate congestion in all of the groups. Generally, these histologic effects appeared to be equivocal between all of the groups, and no abnormalities were noted in the proximal or distal intestine. These findings suggest that feeding channel catfish a diet containing 450 g kg(-1) non-heat-treated RSBM did not cause severe histologic changes associated with soybean meal anti-nutritional factors as have been reported in salmonids.
TL;DR: In this article, complete feedingstuffs for fish, and fishmeals from the Norwegian Fish Feed Monitoring Programme in 2003 were analyzed for their total arsenic and inorganic arsenic contents using microwave assisted wet digestion with nitric acid and hydrogen peroxide was used for the sample preparation for total arsenic analysis by ICPMS.
Abstract: Samples of complete feedingstuffs for fish, and fishmeals from the Norwegian Fish Feed Monitoring Programme in 2003 were analysed for their total arsenic and inorganic arsenic contents. Microwave assisted wet digestion with nitric acid and hydrogen peroxide was used for the sample preparation for total arsenic analysis by ICPMS. Microwave assisted alkaline-alcoholic dissolution of the sample was used for liberation of inorganic arsenic prior to analysis by anion-exchange chromatography High Performance Liquid Chromatography Inductively Coupled Plasma Mass Spectrometry (HPLC–ICPMS). Concentrations in the ranges of 3.4–8.3 and 0.010–0.061 mg kg−1 for complete feedingstuffs were found for total arsenic and inorganic arsenic, respectively. The results are in accordance with typical arsenic levels for fish reported in the literature and indicate that no transformation of chemical arsenic species occurs during the processing of complete feedingstuffs.
Several of the complete feedingstuff samples had total arsenic concentrations above the EU maximum content of 6 mg kg−1 in complete feedingstuffs for fish and complete feedingstuffs for fur animals. However, the species of toxicological relevance, i.e. inorganic arsenic, constitutes less than 1.2% of the total arsenic concentration in these samples. The data illustrate that fish feed with high levels of arsenic, but low levels of inorganic arsenic are at risk of being unnecessarily rejected from the fish feed market. Additionally, the results suggest that the maximum level for total arsenic in fish feed should be re-evaluated and future maximum levels should be based on the chemical species of toxicological relevance, namely inorganic arsenic, rather than on total arsenic.
TL;DR: It is concluded that ZnSO4 in relation to ZnO or Zn-AA was the supplemental zinc source with higher zinc bioavailability to Nile tilapia.
Abstract: A 90-day feeding experiment was conducted with sex reversed Nile tilapia (Oreochromis niloticus) fingerlings fed purified or practical diets supplemented with different zinc sources to evaluate fish growth performance and zinc and iron retention in fish bones, fillets, liver, skin and eyes. The relative bioavailability value (RBV) of zinc in the supplemental sources tested was also calculated. Fish were fed with isonitrogenous and isoenergetic purified or practical diets supplemented with 150 mg Zn kg )1 , as zinc sulphate monohydrate (ZnSO4), zinc oxide (ZnO) or zinc amino acid complex (Zn-AA). The feeding trial was conducted in 30, 50 L aquaria where four 0.66 ± 0.01 g (mean ± SD) fingerlings were initially stocked. No significant differences were observed for any growth performance variables (P > 0.05). In practical diets, only ZnSO4 and ZnO presented bone zinc retention similar to that for the standard zinc source. Zinc concentration in the bone of fish fed practical diet supplemented with Zn-AA (171 ± 3.62 l gg )1 ) was significantly lower than that verified for the practical diets supplemented with the standard zinc source (200 ± 17.7 l gg )1 ) or with ZnSO4 (204 ± 19.9 l gg )1 ). Assuming the concentration of zinc in bones as the response criterion, the supplemental zinc RBV from ZnSO4 (105%) was higher than the RBV for Zn-AA (95.1%) or ZnO (94.9%). Iron concentration in the bones of animals fed the non-zinc-supplemented purified diet was significantly higher than that observed for purified diet supplemented with Zn-AA (P < 0,05). The results of the present work allowed us to conclude that ZnSO4 in relation to ZnO or Zn-AA was the supplemental zinc source with higher zinc bioavailability to Nile tilapia.
TL;DR: A 360-day feeding trial was conducted to observe the influence of varying levels of dietary protein on growth, reproductive performance, body and egg composition of rohu, Labeo rohita, and a dietary protein level of 250 g kg−1 was found optimum with regard to its reproductive performance and egg quality and composition.
Abstract: A 360-day feeding trial was conducted to observe the influence of varying levels of dietary protein on growth, reproductive performance, body and egg composition of rohu, Labeo rohita. Twenty fish (40.4 ± 0.24 cm; 852 ± 4.9 g), stocked in outdoor concrete tanks (200 m2), in duplicate, were fed diets with varying levels (200, 250, 300, 350 and 400 g kg−1) of crude protein exchanged with carbohydrate to apparent satiation, twice daily, at 09:00 and 17:00 h. Higher (P 0.05) among fish of different dietary groups except those fed 200 g kg−1 protein diet which produced least values. Egg diameter remained unaffected (P > 0.05) by variations in levels of dietary protein. Relative fecundity was maximum (P 0.05) by variations in dietary protein level. Hatchability (%) followed the trend of variations almost similar to that of fertilizability. Proximate composition of muscle and eggs varied significantly (P < 0.05) with dietary protein levels. For broodstock L. rohita, a dietary protein level of 250 g kg−1 was found optimum with regard to its reproductive performance, egg quality and composition.
TL;DR: The requirement for l-tryptophan is estimated by nonlinear regression analysis of several growth indicators by using four- and five-parameter saturation kinetics models to increase the precision of diets formulated for hybrid striped bass.
Abstract: Requirements for six of the 10 indispensable amino acids (IAA) have not been quantified for hybrid striped bass. In this study, we estimate the requirement for l-tryptophan by nonlinear regression analysis of several growth indicators. Fifteen isocaloric, isonitrogenous diets were formulated to contain 1.0, 1.3, 1.6, 1.9, 2.2, 2.5, 2.8, 3.1, 3.4, 3.7, 4.0, 5.0, 6.0, 10.0 or 14 g L-tryptophan kg-1 diet and fed to reciprocal cross hybrid striped bass for 7 weeks. After 5 weeks, survival of fish receiving the basal diet was 40% while surviving fish fed this diet were in poor health. Survival of fish receiving 1.3 g Trp kg-1 diet declined to 70% by termination of the trial. Survival in other treatments was 100%. Fish weight gain was 100% or greater for fish receiving 1.6 g Trp kg-1 diet or more. Hepatosomatic index, muscle ratio and intraperitoneal fat (IPF) ratio also responded to dietary tryptophan concentration. IPF was inversely related to dietary tryptophan concentration. The dietary tryptophan requirement was estimated to be between 2.1 and 2.5 g kg-1 diet (6-7 g kg-1 protein), depending on response variable, using four- and five-parameter saturation kinetics models. These findings will increase the precision of diets formulated for hybrid striped bass.
TL;DR: It is indicated that dipeptides can provide IAA to pacu, and that arginine supplemented in this form is utilized as efficiently as in free form.
Abstract: Arginine was hypothesized to be a model compound in the present study on molecular forms of indispensable amino acid (IAA) dietary supplementation. Juvenile South American pacu (Piaractus mesopotamicus) were fed diets containing arginine in a protein base (casein-wheat gluten or casein-gelatin), or the casein-wheat gluten base supplemented with dipeptide or free arginine at two levels (5 and 10 g kg-1). Growth and protein efficiency ratios were significantly affected by diets, but not by arginine molecular form. Three free dispensable amino acids (DAA) and four IAA in plasma were affected by diet, but plasma arginine concentrations did not differ. Plasma urea concentrations, being very low in the pacu, and hepatic arginase activities, were not affected by diet (P = 0.10-0.11), but together with plasma ornithine, mirrored the growth data. Molecular form of arginine supplementation, free or dipeptide, significantly changed several free IAA (Phe, Leu, Ile, His) and urea, with a higher mean plasma concentration in dipeptide fed fish. The dietary treatments, or molecular form of the arginine supplementation, did not change proximate composition, except that calcium levels decreased with higher dietary arginine supplementation level. The present study indicates that dipeptides can provide IAA to pacu, and that arginine supplemented in this form is utilized as efficiently as in free form.
TL;DR: Developing a more stable, single-cell, protein-based diet has a potential to promote gonad production of H. erythrogramma, which was suggested to be the most stable in seawater while the yeast protein diet had the poorest water stability.
Abstract: The nutritive values of three pelleted prepared diets, based on animal (AP), vegetable (VP) and yeast protein (YP) were studied for the sea urchin Heliocidaris erythrogramma (Val.). Fresh macroalga Ulva australis was used as a natural control diet. Triplicate groups of five animals were fed one of the four diets ad libitum every second day for 85 days. Sea urchins fed pelleted feeds had significantly higher food consumption rates (dry basis) and significantly lower total and protein absorption efficiencies compared with the algal diet. The gonad yield and gonad production efficiency in sea urchins fed the natural diet were significantly higher compared with initial group (gonad yield only) and urchins fed animal and vegetable diets, but did not differ significantly from those of the animals fed the yeast diet. Percent protein and lipid in the gonads were not affected by the dietary source. The taste and smell of gonads were generally better in sea urchins collected from the wild or fed yeast and natural diets than in sea urchins fed animal and vegetable diets. The animal protein diet was the most stable in seawater while the yeast protein diet had the poorest water stability. The results of this study suggest that development of a more stable, single-cell, protein-based diet has a potential to promote gonad production of H. erythrogramma.
TL;DR: The weight gain and mineral content of different tissues were significantly affected by dietary Mg levels, while there were no significant differences in ash and zinc content in tissues.
Abstract: An 8-week feeding experiment was conducted to determine the dietary magnesium (Mg) requirement and physiological responses of Litopenaeus vannamei in low salinity water of 2 g L-1. Casein-gelatin-based diets supplemented with seven levels of Mg (0, 0.4, 0.8, 1.6, 3.2, 6.4 and 8.0 g kg-1) were fed to juvenile shrimp. Prior to the experiment, the postlarvae were gradually acclimated to the low salinity media and fed with a basal diet (0.5 g Mg kg-1) for 2 weeks. After 8 weeks of feeding, survival ranged from 80.11% to 85.65% with no significant difference among the treatments. Hepatopancreas Mg2+-ATPase and Na+/K+-ATPase activities and muscle content of lipid and protein were not significantly affected by graded levels of Mg. The weight gain and mineral (calcium, potassium, sodium and total phosphorus) content of different tissues were significantly affected by dietary Mg levels, while there were no significant differences in ash and zinc content in tissues. The Mg content in tissues except hepatopancreas was maintained relatively constant regardless of dietary treatments. The dietary Mg requirement for optimal growth was 2.60-3.46 g Mg kg-1 by using the polynomial regression analysis based on growth.
TL;DR: The analysis revealed that the rate of dry matter loss decreased with time, and that carrageenan and CMC binders were significantly better than agar and gelatine in terms of water stability.
Abstract: Two experiments were conducted to assess the water stability of a practical research diet manufactured with various binders and differing levels of moisture. In the first experiment the binders – agar, gelatine, carrageenan, and carboxymethylcellulose (CMC) were included at both 3 and 5% of total ingredient weight. All binders were tested with equal ingredient weight to water volume, and additionally carrageenan was tested in a diet with double the water volume. The dry matter remaining following immersion for up to 180 min was calculated and the rate of pellet decay was modelled using the Weibull distribution. The analysis revealed that the rate of dry matter loss decreased with time, and that carrageenan and CMC binders were significantly better (P