摄食促进物质对许氏平鲉摄食和生长的影响 不同地理群体星突江鲽养殖子一代群体遗传多样性分析

以初始体重为49．83±．17g的许氏平鲇Sebastesschlegeli为实验对象,进行为期30d的摄食生长实验。共配制6种等氮等能饲料,其中5种饲料以鱼粉和豆粕为蛋白源（豆粕蛋白替代30％的鱼粉蛋白）配制出基础饲料,分别在基础饲料中不添加摄食促进物质和添加0．3％的商品诱食剂、二甲基-β-丙酸噻亭（DMPT）、甜菜碱和柠檬酸配制成5种豆粕替代饲料,其余1种为鱼粉不替代饲料作为对照组,研究摄食促进物质对许氏平鲇摄食和生长的影响。结果表明,当豆粕取代饲料中添加甜菜碱和柠檬酸时,许氏平铀的特定生长率、饲料效率、蛋白质效率以及肝脏、肠胰蛋白酶活力都显著高于不添加摄食促进物质组（P〈0．05）;当不添加摄食促进物质时,摄食率显著低于鱼粉不替代组（P〈O．05）;而添加DMPT、甜菜碱和柠檬酸时,摄食率与鱼粉不替代组比较没有显著差异（P〉0．05）;肝体指数都明显地低于鱼粉不替代组。结果表明,豆粕替代30％的鱼粉蛋白时,添加0．3％的甜菜碱或柠檬酸能够显著提高许氏平鲇幼鱼对饲料的摄食率和生长率。     

Feed intake and growth performance of Senegalese sole (Solea senegalensis Kaup, 1858) fed diets with partial replacement of fish meal with plant proteins

To be able to study nutrient requirement and utilization in any species, a diet supporting normal feed intake and growth equally well as a traditional fish meal‐based diet is needed. Additionally the formulation of the diet should allow low levels of the nutrient under study. When studying the amino acid metabolism and requirements, one cannot rely on the fish meal‐based diets as fish meal are nicely balanced according to requirements. Therefore the current study aimed to develop a plant protein‐based diet (with low fish meal inclusion) to be used in the nutritional studies of Senegalese sole juveniles supporting feed intake and growth close to that obtained in a fish meal‐based control feed. Two experiments were conducted to evaluate whether Senegalese sole juveniles would accept and utilize diets containing high plant protein inclusion. For testing the acceptance of high plant protein inclusion, two diets were formulated: a reference diet that contained fish meal as the main protein source (450 g kg^?1 dry matter) whereas in the test diet, fish meal was substituted by a mixture of plant ingredients (soybean meal, corn and wheat gluten) with l ‐lysine supplementation. In order to improve the palatability, 50 g kg^?1 squid meal was added to both diets. The indispensable amino acids (IAA) profile of the test diet was made similar to the control diet by adding crystalline amino acids. Further, automatic feeders were used to improve the feed intake. Fish (24 g initial body weight) were fed the diets for a period of 4 weeks. As fish accepted both diets equally well, a second study was undertaken to test the growth performance. Fish (6 g initial BW) were fed the diets for a period of 12 weeks. The use of automatic feeders to deliver the feed and the addition of both squid and balancing the indispensable amino acids resulted in growth performance and accretion not differing from the fish meal fed control. It can be concluded that juvenile Senegalese sole are able to grow and utilize high plant‐protein diets when both diet composition and feeding regime are adequate for this species.     

Replacement of Fishmeal with a Blend of Poultry Byproduct Meal and Soybean Meal in Diets for Largemouth Bass,Micropterus salmoides

A feeding trial was conducted to evaluate the potential of replacing fishmeal with poultry byproduct meal (PBM) and soybean meal in diets for largemouth bass, Micropterus salmoides. A reference diet (C) contained 400 g/kg fishmeal, and 40 or 60% of the fishmeal was replaced with a blend of pet‐food‐grade PBM and soybean meal (diets PP1 and PP2) or a blend of feed‐grade PBM and soybean meal (diets PF1 and PF2). No significant differences were found in weight gain, nitrogen retention efficiency (NRE), condition factor, and body composition among fish fed diets PP1, PP2, PF1, and PF2. Feed intake and feed conversion ratio (FCR) were higher in fish fed diet PF1 than in fish fed diet PP1. No significant differences were found in weight gain, NRE, condition factor, and body composition between fish fed diet C and diets PP1, PP2, PF1, and PF2. The feed intake and FCR were lower in fish fed diet C than in fish fed diets PP2, PF1, and PF2. This study reveals that dietary fishmeal level for largemouth bass could be reduced to 160 g/kg by inclusion of PBM and soybean meal in combination.     

Effects of dietary taurine levels on epidermal thickness and scale loss in red sea bream,Pagrus major

Taurine is often added to artificial fish diets to compensate for a reduction in fish meal (FM). However, the taurine content of FM‐based diets is typically lower than in diets consisting of raw fish, even in diets where FM is the only protein source. We evaluated the effects of dietary taurine in FM‐based diets on epidermal thickness and scale detachability in red sea bream Pagrus major. We compared the effect of diets containing 0% (control), 0.3% (Tau‐0.3%), 0.6% (Tau‐0.6%) and 1.0% (Tau‐1.0%) taurine. Red sea bream (average body weight, 39 g) were fed these diets for 7 weeks. Taurine supplementation had no effect on growth, feed intake, feeding efficiency, or survival. However, the epidermal thickness was higher in fish in the Tau‐0.6% and Tau‐1.0% groups than in the control and Tau‐0.3% groups. Similarly, scale loss was significantly higher in the control group than in the Tau‐0.6% and Tau‐1.0% groups. Our results suggest that supplementation with >0.6% taurine (1.0% in diet) improves skin condition.     

Periodic changes in the growth performance and biochemical composition of juvenile red sea bream <Emphasis Type="Italic">Pagrus major</Emphasis> fed non-heated and heated squid and krill meal-based diets

In finfish aquaculture, fish meal is heated during the manufacturing process, which affects the digestibility and protein absorption by fish. However, manufactured fishmeal that is not heated does not undergo thermal denaturation. Few studies have investigated the effects of non-heated animal protein sources on the growth performance of fish. We investigated the effects of heated and non-heated squid and krill meal as diets for red sea bream. Five test diets were formulated to contain heated squid meal, non-heated squid meal, heated krill meal, non-heated krill meal, and fish meal as a control. Fifty fish (initial mean weight?=?3.5 g) were distributed in ten 100-l experimental tanks. Fish were fed one of the five diets 3 times daily until satiation for 5 weeks. Regarding growth performance, fish fed the krill meal diet exhibited better growth than those fed squid meal during the first week of the rearing period. However, the squid meal diet group showed better performance than the krill meal diet group during the third week. Moreover, differences in body weight among treatments were greater during the fifth week. Better weight gain and thermal growth coefficient were recorded in the non-heated diet groups than in the heated diet groups. Higher feed intake was observed in the non-heated diet groups than in the heated diet groups. These results suggest higher performance of non-heated squid and krill meal as the protein source of the red sea bream diet. Further, the suitability of the diet type (e.g., squid and krill) might depend on the feeding period and/or developmental stage of fish.     

Effects of different feed stimulants on freshwater crayfish (Procambarus clarkii), fed diets with or without partial replacement of fish meal by biofeed

The feeding trials were carried out with freshwater crayfish (Procambarus clarkii) to evaluate the three feed stimulants betaine (Bet), squid extract (SE) and squid meal (SM) upon fish meal (FM) diets or biofeed (BF) diets in which FM were partially replaced by BF. Results showed the three feed stimulants had no significant effect on growth. By the relative concentration of markers in the faeces and diets, the preference for each diet was estimated, and the best stimulant was the mixture of Bet, SE and SM. As FM replaced by BF increased, added with the mixture, the relative weight gain showed an increasing trend, but decreased significantly by 30% replacement. With the substitution increasing, trypsin activities increased, whereas decreased too upon 30% substitution. Less than 30% replacement, there was no significant effect on muscle proximate composition, intestine amylase activities and serum haemocyanin contents, except the drop of lipid. The results indicated that the mixture of Bet, SE and SM could perform well as a feed stimulant. And with the addition of the mixture, FM in the diet could make about no more than 20% saving without any adverse effects.     

Feeding of juvenile cobia,Rachycentron canadum: Evaluation of practical feeds,comparison of commercial fishmeal replacers,and estimation of essential amino acid requirements

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.     

Feed intake and growth of Arctic charr, Salvelinus alpinus (L.), fed diets supplemented with oxytetracycline and squid extract

This study examined the long-term effects of a potential feeding deterrent, oxytetracycline (OTC), and a putative feeding stimulant, squid extract, on feed intake, growth and dry matter (DM) digestibility in Arctic charr, Salvelinus alpinus (L.). Fish were fed one of four diets for 9 weeks: 1. commercial feed formulation (basic); 2. BM (basic plus 20 g kg⁻¹ OTC); 3. BMS (BM plus 10 g kg⁻¹ squid extract); 4. BS (basic plus 10 g kg⁻¹ squid extract). The feed intake of Arctic charr was not reduced by the addition of OTC to the basic feed, and addition of squid extract to the medicated feed did not enhance feed consumption. DM digestibility and growth tended to be reduced in groups of fish fed diets supplemented with the antibiotic (BM and BMS). This suggests that OTC may have interfered with nutrient digestion and absorption. OTC does not seem to be a feeding deterrent for Arctic charr, possibly indicating that the charr is a rather unselective feeder. Because the medicated feeds were readily accepted, there may be little to be gained by addition of feeding stimulants to these types of feeds for charr.     

Chlorella additive increased growth performance,improved appetite and immune response of juvenile crucian carp Carassius auratus

This study was designed to investigate effects of dietary Chlorella meal (CM) additive on growth performance, immune responses and appetite regulation of juvenile crucian carp Carassius auratus (initial body weight: 1.27 ± 0.03 g). Four experimental diets were formulated to contain 0% (CM0), 1% (CM1), 2% (CM2) and 4% Chlorella meal (CM4), respectively. Each diet was randomly assigned to triplicate groups with 40 juvenile fish per fibreglass tank for 8 weeks. Weight gain rate, specific growth rate and feed intake increased with increasing dietary CM levels. In contrast, FCR (feed conversion rate) declined with dietary CM levels. No significant differences were observed in moisture, crude protein, crude lipid and ash contents of muscle and liver tissues. Dietary CM addition increased activities of acid and alkaline phosphatase in liver and kidney. Dietary CM up‐regulated the mRNA expression levels of NKEF‐B, MCHII and IgM in kidney, and increased the mRNA levels of NPY and agouti gene‐related protein in the brain, but down‐regulated mRNA levels of MC4R, LEP, LEPR, CART1, CART2 and CCK8 genes. Based on these observations above, this study indicated that dietary CM additive increased growth performance, immune responses and appetite of crucian carp. The results, for the first time, demonstrate a role for the central nervous system in the control of food intake in fish fed dietary Chlorella meal.     

Effects of dietary phospholipid level and fraction on the feed intake of non‐fish meal diet in yellowtail,Seriola quinqueradiata Temminck & Schlegel, 1845

Three feeding studies were conducted to investigate whether dietary soybean lecithin (SBL) enhanced feed intake of non‐fish meal, SPC‐based diet, in yellowtail, and also to clarify which fraction of phospholipid (PL) was effective to enhance feed intake. In experiments 1 and 2, fish were fed SBL level at 0%–5%, and it was revealed that the daily feeding rate (DFR) of fish was significantly higher for SBL 2% than for SBL 0%, while a further increase of SBL in the diet did not additionally increase the DFR. Moreover, the DFR of fish fed a diet without feeding stimulants (FS) was the lowest among the dietary treatments, indicating that the SBL does not have an effect of enhancing feed intake in yellowtail. In experiment 3, fish were fed a diet with several products containing PL at 2%. Phosphatidylcholine and phosphatidylinositol concentrations in these products positively correlated to the DFR of fish. This result revealed that these two fractions in the SBL are effective for enhancing feed intake of yellowtail when FS is present in the diet.     

Effect of guava Psidium guajava (L.) aqueous extract diet on growth performance,intestinal morphology,immune response and survival of Oreochromis niloticus challenged with Aeromonas hydrophila

An 84‐day feeding trial was carried out to evaluate the effects of aqueous Psidium guajava leaf extract (PGE) on growth, intestinal morphology, physiology, immune response and susceptibility of Oreochromis niloticus to Aeromonas hydrophila. Diets containing 0% (P0), 0.25% (P1), 0.50% (P2), 0.75% (P3) and 1.00% (P4) PGE were fed to triplicate groups of fish (mean weight; 1.32 ± 0.04 g) for 84 days. After the 84‐day feeding trial, test fish were injected with pathogenic A. hydrophila and then fed for 14 days. More feed were consumed in groups of fish fed PGE‐treated diets and resulted in significantly higher weight gain and feed intake. Incidentally, there was an increase in the calculated area of absorption of fish fed PGE diets, as accounted for by marginally higher villi length and width. Antioxidant and immune response were improved with PGE inclusion in diets as total protein, superoxide dismutase, glutathione peroxidase and glutathione S‐transferase significantly increased (p < 0.05) in fish fed PGE diets. Results of the challenge test with A. hydrophila revealed that the highest mortality (100%) was recorded in P0. This study revealed that inclusion of P. guajava extract in the diet of O. niloticus improved growth, nutrient utilization, immune system and survival of O. niloticus fingerlings.     

Interactive effects of salinity and complete fishmeal replacement on growth,food consumption,and gene expression of hepatic IGF‐I,IGF‐II and growth hormone receptors in Nile tilapia,Oreochromis niloticus (L.)

A 12‐week feeding trial was conducted using Nile tilapia, Oreochromis niloticus (L.) to evaluate the interactive effects of fishmeal replacement and salinity on growth, feed utilization efficiencies and relative expression of growth related genes. Two iso‐nitrogenous and iso‐energetic diets were prepared (32% protein). The control diet included 15% fishmeal (FM diet) and fishmeal component in non‐fishmeal diet (NFM) was eliminated by a mixture of poultry by‐product meal, high protein distillers dried grains and distillers dried grains with soluble. The NFM diet was supplemented with DL‐methionine and L‐lysine. Duplicated group of fish with initial mean weight of 6 g, reared in four salinity levels (0, 4, 8 and 12 g/L) were fed one of the two diets twice a day to near satiety. At the end of the experiment, growth, feed utilization efficiency and expression of growth related genes were compared. The specific growth rate (SGR), mean feed intake (MFI) and feed conversion ratio (FCR) were not affected by the diets while salinity effects were significant. The fish in the 4 g/L salinity showed the highest SGR and MFI while fish in the 0 g/L treatment showed the lowest FCR. Relative expression of hepatic IGF‐I and IGF‐II was regulated by salinity but not by the diet. Expression of growth hormone receptor gene was not affected by either diet or salinity. The present findings provide evidence for the possibility of total fishmeal replacement in saline waters (0–12 g/L) without compromising growth, feed utilization and body composition of Nile tilapia.     

Effects of five compound attractants in high plant‐based diets on feed intake and growth performance of juvenile turbot (Scophthalmus maximus L.)

An experiment was conducted to evaluate the effects of five attractants on feed intake, growth performance and appetite‐regulating genes expression for juvenile turbot (Scophthalmus maximus L.). Fish were fed with seven diets: fish‐meal‐based diet (FM), fermented soybean meal replacing 45% fish meal (FSBM) and other diets with 1% compound attractant A (CA‐A) consisting of amino acids, compound attractant B (CA‐B) consisting of quaternary ammonium bases, compound attractant C (CA‐C) consisting of nucleotides, compound attractant G (CA‐G) consisting of the combination of CA‐A, CA‐B and CA‐C and blue mussel protein hydrolysate (BMH) on the basis of FSBM diet respectively. Daily feed intake in CA‐A group was significantly higher, but that in CA‐B group was significantly lower than FSBM group. Similarly, specific growth rate was significantly enhanced in CA‐A and CA‐G groups and were significantly decreased in CA‐B group. Protein efficiency ratio and protein retention in CA‐B group were significantly lower than FSBM group. Furthermore, BMH supplement increased the mRNA expression of Ghrelin in the intestine of fish. These results showed that CA‐A and CA‐G supplement could enhance growth in plant‐based diets, but CA‐B supplement had the opposite effect, which might be associated with lower feed intake and lower feed utilization.     

Total fish meal replacement with canola protein isolate in diets fed to rainbow trout (Oncorhynchus mykiss W.)

The potential of canola protein isolate (CPI) as fish meal alternative in diets for rainbow trout was evaluated. Apparent digestibility coefficients (ADCs) for protein from a fish meal‐based reference diet (89.2 ± 1.1%) and CPI (84.6 ± 1.8%) were determined by indirect marker method in a digestibility experiment. ADC of dietary dry matter was slightly lower for the reference diet (62.5 ± 4.7%), but not significantly different to the CPI test diet (65.9 ± 3.1%). In a subsequent growth trial, 20 fish (initial weight 31.5 ± 0.5 g) were stocked into each of 15 experimental tanks of a freshwater flow‐through system. Fish were organized in triplicate groups and received experimental diets with 0%, 25%, 50%, 75% and 100% of fish meal replaced with CPI on the basis of digestible protein (designated as Control, I25, I50, I75, I100 respectively). At the end of a 70‐day feeding period, growth performance, feed intake and feed conversion ratio of treatment groups receiving diets I25, I50 or I100 were similar to the control group, while fish fed diet I75 showed significantly higher weight gain caused by improved feed conversion. The tested CPI was therefore identified to be a highly valuable fish meal alternative, not negatively affecting diet palatability, feed intake and feed efficiencies.     

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

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

Replacement of fishmeal by soy protein concentrate with taurine supplementation in diets for golden pompano (Trachinotus ovatus)

Two 7‐week feeding trials were conducted to evaluate the capacity of golden pompano (Trachinotus ovatus) to use soy protein concentrate (SPC) as a dietary fish meal substitute. In trial I, fish were fed with a control diet (C) containing 400 g kg^?1 fish meal and other four diets in which the fish meal in diet C was replaced by SPC at 20 (R20), 40 (R40), 60 (R60) and 80% (R80). In trial II, a 3 × 2 design was used, and 40 and 80% of the fish meal in diet C were replaced by SPC, with or without 5 g kg^?1 taurine supplementation (six diets, C + T, R40 + T, R80 + T, C, R40 and R80, were formulated). In trial I, no significant difference was found in the feed intake between feeding treatments. The weight gain and nitrogen retention efficiency (NRE) decreased, whereas the feed conversion ratio (FCR) and phosphorus retention efficiency (PRE) increased, with decreasing dietary levels of fish meal. No significant differences were found in the weight gain, FCR and NRE between fish fed diets C and R20, whereas fish fed diets C and R20 had higher weight gain than those fed diets R40, R60 and R80. In trial II, no significant differences were found in the feed intake, weight gain, FCR, NRE and PRE between fish fed diets C + T and C. No significant differences were found in the feed intake, weight gain and NRE between fish fed diets R40 and R40 + T or between fish fed diets R80 and R80 + T. At the end of trial II, no significant differences were found in the condition factor, hepatosomatic index and body composition between fish fed diets C and C + T, or between fish diets R40 and R40 + T, or between fish fed diets R80 and R80 + T, except that fish fed diet R40 had lower body protein content than that of fish fed diet R40 + T. The present study reveals that taurine supplementation can elevate fish meal replacement level by SPC in the golden pompano diets. Fish meal can be reduced from 400 to 320 g kg^?1, if fish meal is substituted by SPC without taurine supplementation, and can be further reduced to 240 g kg^?1, if fish meal is substituted by SPC with 5 g kg^?1 taurine supplementation.     

Effect of replacing fish meal with soybean meal on growth,feed utilization and nitrogen and phosphorus excretion of juvenile Pseudobagrus ussuriensis

An 8‐week feeding trial was conducted to evaluate the effects of replacing fish meal with soybean meal (SBM) on growth, feed utilization, and nitrogen (N) and phosphorus (P) excretion of juvenile Pseudobagrus ussuriensis (initial average weight 0.50 ± 0.00 g). Seven isonitrogenous and isolipidic diets were formulated to contain SBM to replace fish meal protein at 0% (S0), 10% (S10), 20% (S20), 30% (S30), 40% (S40), 50% (S50) and 60% (S60) respectively. To investigate the effects of supplementation with crystalline amino acid to balance diet S60, one diet was formulated to add 0.30% methionine (SM60). The results showed that there was no significant difference in weight gain among fish fed S0, S10, S20, S30 and S40 diets, however, a significant reduction in this variable occurred when 50% and 60% of fish meal protein was replaced by SBM (P < 0.05). Apparent digestibility coefficients of dry matter, crude protein and phosphorus of diets were affected by dietary SBM levels. N and P excretion indicate that fish meal replacement by SBM led to an increase in N excretion, but led to a reduction in P excretion. No differences were detected in growth, feed utilization and N and P excretion between fish feed diets S60 and SM60. The results of this study show that 40% of fish meal protein could be replaced by SBM in diets of juvenile P. ussuriensis without having a significant negative effect on growth or feed efficiency, but that higher dietary SBM levels reduce fish performance.     

Evaluation of corn gluten meal as a protein source in diets for gilthead sea bream (Sparus aurata L.) juveniles

A 12‐week growth trial was conducted to evaluate corn gluten meal as an alternative protein source to fish meal in diets for gilthead sea bream juveniles. The experimental diets were formulated to be isonitrogenous and isoenergetic and to have 20%, 40%, 60% and 80% of fish meal protein, the only protein source in the control diet, replaced by corn gluten meal. At the end of the growth trial only the group fed the diet with 80% corn gluten protein exhibited significantly reduced growth and feed efficiency compared with the fish meal‐based diet. This was most likely due to a dietary amino acid deficiency in that diet. A trend was noticed for feed efficiency to improve with the replacement of fish meal protein in the diets up to 60%. There were no significant differences among groups in protein and energy retention (as percentage of intake). At the end of the trial whole body water content of the experimental groups was significantly lower and the lipid content of groups including 60% and 80% corn gluten protein was significantly higher than that in the control. No other differences were observed in whole body composition among groups. Apparent digestibility coefficients (ADC) of the diets were evaluated in a separate trial. The ADC of dry matter of the experimental diets was significantly higher than in the control diet; there were no significant differences among diets in the ADC of energy and protein, except for the ADC of protein of diet with 80% corn gluten protein, which was significantly lower than the control. The results of this study indicate that corn gluten meal can replace up to 60% fish meal protein in diets for gilthead sea bream juveniles with no negative effects on fish performance.     

Replacement of dietary fish meal by soybean meal supplemented with crystalline methionine for Japanese seabass (Lateolabrax japonicus)

Two 8‐week feeding trials were conducted to evaluate soybean meal (SBM) as a fish meal substitute in diets for Japanese seabass, Lateolabrax japonicas. In trial I, a control diet (C) contained 400 g kg^?1 fish meal, and 20%, 40%, 60% and 80% of the fish meal were replaced with SBM, supplied with 3 g kg^?1 DL‐methionine and 2 g kg^?1 L‐lysine (S20, S40, S60 and S80). In trial II, 60% and 80% of the fish meal in diet C were replaced with SBM, supplied with DL‐methionine at 3 g kg^?1 (S60, S80) or 6 to 7 g kg^?1 (RS60, RS80). The feed intake was lower in fish fed diet C than in fish fed diets S20, S40, S60 and S80 (trial I). No significant differences were found in the weight gain, nitrogen retention efficiency and body composition between fish fed diets C, S20, S40 and S60 (trial I), between fish fed diets S60 and RS60 or between fish fed diets S80 and RS80 (trial II). This study indicates that dietary fish meal level for Japanese seabass can be reduced to 160 g kg^?1 by using SBM as a fish meal substitute.     

Tributyrin‐supplemented high‐soya bean meal diets of juvenile black sea bream,Acanthopagrus schlegelii: Study on growth performance and intestinal morphology and structure

An 8‐week growth trial was conducted to evaluate the effects of different levels of tributyrin supplementation in a high‐soya bean meal diet on juvenile black sea bream (11.30 ± 0.16 g). The positive control (PC) diet contained 45% fishmeal and 20% soya bean meal, while the negative control (NC) contained 12% fishmeal and 45% soya bean meal. Graded levels of tributyrin were added to the NC diet at 0.05% (TB 0.05), 0.1% (TB 0.1), 0.2% (TB 0.2), 0.4% (TB 0.4) and 0.8% (TB 0.8). Ultimately, the fish fed the PC diet had a higher weight gain and specific growth rate than the fish fed other diets. The fish fed the NC diet had the lowest growth, and TB 0.05–TB 0.2 diets increased growth performance while TB 0.4–TB 0.8 diets caused reduction in growth. Dietary tributyrin supplementation improved protease activity and enhanced antioxidant capacity. Compared with the fish fed the NC diet, the fish fed the tributyrin‐supplemented diets had improved gut morphology and structure, and the results were similar to those of the fish fed the PC diet. Furthermore, the analysis of the dose response with second‐order polynomial regression indicated that the optimum tributyrin supplementation for juvenile black sea bream is 2.24 g/kg in the 45% soya bean meal diet.