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We replaced fish meal (FM) with porcine blood meal (BM) in red sea bream (Pagrus major) diets to examine the influence on growth performance. Four experimental diets were prepared to be isonitrogenous and isolipidic by replacing 0%, 10%, 20% and 30% FM protein with BM (BM0, BM10, BM20 and BM30, respectively). After the 8‐week feeding trial, the final mean body weight, weight gain, specific growth rate, daily feeding rate, condition factor and survival rate were not significantly different among the treatments (p > 0.05). However, feed efficiency tended to lower linearly as the dietary BM level increased, and no significant difference was observed between the BM20 and BM0 groups (p < 0.05). The protein digestibility in the BM20 and BM30 groups decreased significantly compared with that in the BM0 group (p < 0.05). Fat digestibility decreased significantly in the BM30 group than in other treatment groups (p < 0.05). The total serum protein and total cholesterol concentrations in the BM30 group were the highest among all treatment groups. In conclusion, BM can replace up to 20% of FM in the red sea bream diet without adversely affecting growth performance. [ABSTRACT FROM AUTHOR]

The stress physiology and welfare needs of red seabream, a fish species with high nutritional and economic value for aquaculture, have been poorly studied. The aim of the current study was to investigate physiological responses of red seabream to potential environmental and husbandry stress factors. We quantified the acute stress response of fish exposed to a standardized acute chasing stress protocol as well as to transportation stress, by analysing acute stress biomarkers such as plasma concentrations of cortisol, glucose, lactate and osmolality. Moreover, the physiological status of fish reared at different water temperatures (15, 20 and 25°C) was also studied by analysing plasma parameters and cortisol concentration in scales. Results showed that in most estimated parameters, red seabream showed a fast response and recovery to acute stress. On the contrary, recovery after an 18‐h transportation stress was prolonged and required more than one day. Finally, rearing of fish at different temperatures also affected stress indicators such as plasma cortisol and glucose, while lactate and osmolality were not significantly affected. Regarding cortisol concentration in fish scales, a chronic stress indicator, results showed that fish reared at 15°C had a significantly higher cortisol concertation of scales than those exposed to 25°C. The data provide a better insight into the effect of husbandry and environmental factors on red sea bream stress physiology and welfare. [ABSTRACT FROM AUTHOR]

Black soldier fly meal (BM) is an outstanding candidate as a fish meal (FM) substitute because it contains relatively high protein and essential amino acids. In this study, we replaced FM in red sea bream diets (Pagrus major) with BM to investigate its effect on growth and feed utilization. Six isonitrogenous and isolipidic experimental diets were prepared by substituting 0%, 20%, 40%, 60%, 80% and 100% FM protein with BM (Control, BM20, BM40, BM60, BM80 and BM100, respectively). After the 8‐week feeding trial, final body weight, weight gain, specific growth rate and feed efficiency decreased linearly with increasing dietary BM level (p < 0.05). Apparent digestibility of protein and fat and serum total cholesterol concentration decreased with increasing dietary BM levels (p < 0.05) Final body weight, WG, SGR and FE against dietary BM level had breaking points of 76.2%, 41.7%, 76.5% and 60.0%, respectively, in segmental regression analysis. In conclusion, the results suggest that BM can replace a maximum of 41.7% of FM in the diet of red sea bream without compromising growth performance or feed efficiency for 56 days. [ABSTRACT FROM AUTHOR]

A feeding experiment was conducted to survey proper microalgae species for nonfish meal and non-fish oil diet of red sea bream. Five iso-nitrogenous and iso-lipidic diets were formulated (CP 47%, CL 19%). Fish oil formulated non-fish meal diet was arranged as a control diet with soybean meal, soy protein concentrate and corn gluten meal (FO). Fish oil of FO was replaced by Nannochloropsis meal and Schizochytrium meal for each of two diets (NAN, SCH). Both microalgae meals were mixed in a diet (NS), and Chlorella meal was formulated in NS diet to replace plant protein source (NSC). Duplicated groups of juvenile red sea bream (5.9 g) were fed the experimental diets for 75 days to near satiation. The growth was the highest in NS and NSC diet group. The other algae meal formulated diets fed groups showed the similar growth performance to FO. In fatty acid profiles, NAN group showed the lowest n-3 LC-PUFA with low DHA content in fatty acid composition of total lipid in fish carcass and hepatic PL, but the other algae meal diet group showed no significant difference with FO group. The results might suggest blending microalgae and using them with high amount is a key strategy for development of non-fish meal and non-fish oil diet for red sea bream. [ABSTRACT FROM AUTHOR]

Considering the high nutritional value of fish as food, in combination with the worldwide problem of overfishing, aquaculture constitutes a major sector of economic activity. Consumers of marine products are affected by the appearance and particularly of the fish colour. In this context, the coloration of the final product represents an important criterion for its final selection. The European Food Safety Authority has enacted a legislation regarding coloration in food. Although colour on the skin of fish is principally genetically determined, fish are unable to produce colour pigments. Therefore, diet is directly related to colour and the most common pigment is carotenoids. One of the most successful examples of aquaculture, in terms of skin coloration, is the red porgy Pagrus pagrus. Concerning the achievement of its colour, concatenated data from different studies show that the most effective method is the combination of two factors: diet with astaxanthin and maintenance of fish in short‐term periods in white background before sale. Moreover, alternative and effective ways for achievement of the desired colour are the submerged cages and the in sea cages with canopies. However, knowledge about carotenoids regarding fish coloration is scarce. Thus, future research is needed in order to elucidate the underlying mechanisms concerning the chromatic plasticity in the skin of fish. [ABSTRACT FROM AUTHOR]

Abstract: A 70‐day experiment was conducted to examine the effects of different macroalgal meals and lipid sources on growth, body wall composition and fatty acid (FA) profile of sea cucumber Apostichopus japonicus. Two macroalgal meals including Sargassum muticum (SM) and Gracilaria lemaneiformis (GL) and two lipid sources including fish oil (FO) and vegetable oil (VO) were formulated into four diets, i.e., S. muticum and fish oil (SF), S. muticum and vegetable oil (SV), G. lemaneiformis and fish oil (GF) and G. lemaneiformis and vegetable oil (GV). The results showed that the specific growth rates (SGR) of A. japonicus fed diets containing SM were significantly higher than those fed diets containing GL. No significant differences in SGR between the FO‐based and VO‐based groups were observed. Similar results were observed in the body wall lipid content. Most body wall FAs changed to resemble the dietary FA proportions because of the dietary effect. Concentrations of 20:4n‐6 of the SF and GF groups were significantly lower than the SV and GV groups, while levels of 20:5n‐3 and 22:6n‐3 were significantly higher than the SV and GV groups. The n‐3/n‐6 polyunsaturated fatty acids (PUFA) ratios of the SF and GF groups were significantly higher than the SV and GV groups. Moreover, the SF group had significantly higher 20:5n‐3 and 22:6n‐3 contents and n‐3/n‐6 PUFAs ratio than the GF group. These findings reveal that the SF diet can show beneficial effects on both growth performance and body wall n‐3 PUFAs content of A. japonicus. [ABSTRACT FROM AUTHOR]

Abstract: Hybrid seabream (Pagrus major♀ × Acanthopagrus schlegelii♂) grow quickly, with retarded gonadal growth and enhanced muscle nutritional composition. This F1 hybrid seabream is a new marine aquaculture fish in China. However, the response of hybrid seabream to transport is severe, which seriously restricts its promotion and development. Water quality and the physiological response of hybrid sea bream were studied at three fish transport densities (5, 10 and 20 g/L) during 8 hr of transport in a light van (60 km hr−1 and 25°C water temperature). We found that total ammonia–nitrogen and nitrite–nitrogen levels in the water of the highest density group increased sharply after 4 and 8 hr of transport. Cumulative survival of the fish in the 10 and 20 g/L groups (86.7% and 75% respectively) was significantly lower than in the 5 g/L group (100%) after 8 hr of transport (p < .05). Serum cortisol and lactate levels were significantly higher after transport than pre‐stress levels, whereas the glucose level decreased significantly (p < .05). Hepatic triglyceride and glycogen levels and superoxide dismutase and catalase activities were significantly lower in the 20 g/L group than in the 5 g/L group (p < .05). The results show that high‐density transport increased ammonia–nitrogen and nitrite–nitrogen levels in the water as well as cortisol secretion and anaerobic metabolism in the F1 hybrid seabream, suggesting that total cholesterol and glycogen may be used to supply the energy demand and increased oxidative stress. These results will help to optimize the transport conditions for cultured hybrid seabream. [ABSTRACT FROM AUTHOR]

The effects of the dietary medicinal herbs Massa medicata, Crataegi fructus (Cf), Artemisia capillaries, Cnidium officinale and their mixture (HM), on growth and resistance against Vibrio anguillarum were examined using larval red sea bream, Pagrus major. The methanol extracts of Cf and HM inhibited the proliferation of seven infectious bacterial strains including the genera Aeromonas, Edwasiella, Photobavterium, Pseudomonas and Vibrio. Rotifers enriched with emulsified bonito oil containing extracts of Cf and HM lowered the bacterial counts in their body on TCBS medium for the genus Vibrio in comparison with rotifers enriched by emulsified bonito oil alone. Although statistically not significant, larvae fed rotifer fortified with Cf from 3 to 20 days after hatching showed the best growth and final body weight followed by those given rotifer with HM and control enrichment. However, final body length of larvae fed rotifer with Cf was significantly larger than larvae fed on rotifers enriched with other herb extracts. After a challenge test with V. anguillarum, survival of larvae fed rotifer with Cf and HM was significantly higher than for the control treatment. These results revealed that Cf and HM in rotifer is useful to promote growth and resistance against V. anguillarum in red sea bream larvae, providing a new technology for mass production of disease-resistant fry and fingerlings. [ABSTRACT FROM AUTHOR]

Adult red sea bream, Pagrus major (body weight, 1.0–2.0 kg) was exposed to three photoperiods [12 h light:12 h dark (12L:12D), 16 h light:8 h dark (16L:8D) and 24 h light:0 h dark (24L:0D)] from 2 months before spawning till the end of the spawning season to investigate growth, spawning and stress response. During the spawning season, tanks were checked every morning for spawned eggs. The growth performance in fish under 24L:0D was stimulated with significantly higher feed intake than those under other photoperiods ( P<0.05). The number of eggs and gonadal histology confirmed that three and five females out of six in each of duplicate tanks of the 16L:8D treatment spawned. In contrast, only two out of six females in one tank of the 24L:0D treatment spawned, and no spawns were observed in the 12L:12D treatment. At the end of the spawning period, both 17β-estradiol and testosterone levels were significantly higher in fish exposed to 16L:8D followed by 12L:12D and 24L:0D photoperiods ( P<0.05). Photoperiod manipulation did not cause significant stress response in fish ( P>0.05). The results suggest that stimulating the growth performance of red sea bream at reproductive stage with a 24L:0D photoperiod is possible if the fish are subjected to this photoperiod long before the onset of the spawning season. [ABSTRACT FROM AUTHOR]

The present study was designed to determine the positive effects of artificial illumination on the juvenile black seabream, Acanthopagrus schlegeli, by comparing stomach contents and growth between juveniles exposed to light and those maintained in the absence of light. The major prey items for juvenile black seabream reared in illuminated cages were amphipods (IRI%=50.5), copepods (IRI%=44.7) and polychaetes (IRI%=3.0), whereas those for the juveniles maintained in unilluminated cages were copepods (IRI%=96.0), amphipods (IRI%=3.4) and polychaetes (IRI%=0.6). The specific growth rates (SGR) of the juveniles reared in illuminated cages (0.99%) were significantly higher than those of the juveniles maintained in unilluminated cages (0.78%). [ABSTRACT FROM AUTHOR]

The unnaturally dark pigmentation of cultured Australian snapper Pagrus auratus can be improved through dietary astaxanthin supplementation and by holding fish in tanks with a white background. The practical application of these laboratory-based findings was examined with two experiments to establish if the advantages of transferring fish to light coloured tanks before harvest could be achieved on-farm using white cages and to determine the effects of fish density on skin colour. For the first experiment, snapper (mean TL=29.7 cm) were transferred from a commercial snapper sea cage to black or white netted cages and fed diets supplemented with unesterified astaxanthin (supplied as Lucantin® Pink, BASF) at 0 or 39 mg kg−1 for 42 days. Skin colour was measured using the CIE (black–white), (green–red), (blue–yellow) colour scale. Snapper held in white netting cages became significantly lighter (higher ) than snapper held in black cages; however, values were not as high as previous laboratory-based studies in which snapper were held in white plastic-lined cages. Snapper fed astaxanthin displayed significantly greater and values, and total carotenoid concentrations after 42 days. In addition, total carotenoids were higher in fish from black than white cages. The second experiment was designed to investigate whether density reduced the improvements in skin colour achieved by holding fish in white coloured cages and whether cage colour affected stress. Snapper (mean weight=435 g) were acclimated to black cages and fed 39 mg kg−1 astaxanthin for 44 days before transferring to black or white plastic-lined cages at 14 (low), 29 (mid) or 45 (high) kg m−3 for 7 days after which time skin colour, plasma cortisol and plasma glucose concentrations were measured. Skin lightness ( ) was greater in snapper transferred to white plastic-lined cages with the lightest coloured fish obtained from the lowest density after 7 days. Density had no effect on plasma cortisol or glucose levels after 7 days, although plasma cortisol was elevated in snapper from black cages. For improved skin colouration we recommend feeding unesterified astaxanthin at 39 mg kg−1 for approximately 6 weeks and transferring snapper to white plastic-lined cages or similar at low densities for short periods before harvest rather than producing fish in white netting sea cages subject to biofouling. [ABSTRACT FROM AUTHOR]

Three 2-factor experiments were conducted to determine the effects of background colour and synthetic carotenoids on the skin colour of Australian snapper Pagrus auratus. Initially, we evaluated the effects on skin colour of supplementing diets for 50 days with 60 mg kg−1 of either astaxanthin (LP; Lucantin® Pink), canthaxanthin (LR; Lucantin® Red), apocarotenoic acid ethyl ester (LY; Lucantin® Yellow), selected combinations of the above or no carotenoids and holding snapper (mean weight=88 g) in either white or black cages. In a second experiment, all snapper (mean weight=142 g) from Experiment 1 were transferred from black to white, or white to white cages to measure the short-term effects of cage colour on skin L*, a* and b* colour values. Skin colour was measured after 7 and 14 days, and total carotenoid concentrations were determined after 14 days. Cage colour was the dominant factor affecting the skin lightness of snapper with fish from white cages much lighter than fish from black cages. Diets containing astaxanthin conferred greatest skin pigmentation and there were no differences in redness ( a*) and yellowness ( b*) values between snapper fed 30 or 60 mg astaxanthin kg−1. Snapper fed astaxanthin in white cages displayed greater skin yellowness than those in black cages. Transferring snapper from black to white cages increased skin lightness but was not as effective as growing snapper in white cages for the entire duration. Snapper fed astaxanthin diets and transferred from black to white cages were less yellow than those transferred from white to white cages despite the improvement in skin lightness ( L*), and the total carotenoid concentration of the skin of fish fed astaxanthin diets was lower in white cages. Diets containing canthaxanthin led to a low level of deposition in the skin while apocarotenoic acid ethyl ester did not alter total skin carotenoid content or skin colour values in snapper. In a third experiment, we examined the effects of dietary astaxanthin (diets had 60 mg astaxanthin kg−1 or no added carotenoids) and cage colour (black, white, red or blue) on skin colour of snapper (mean weight=88 g) after 50 days. Snapper fed the astaxanthin diet were more yellow when held in red or white cages compared with fish held in black or blue cages despite similar feed intake and growth. The skin lightness ( L* values) was correlated with cage L* values, with the lightest fish obtained from white cages. The results of this study suggest that snapper should be fed 30 mg astaxanthin kg−1 in white cages for 50 days to increase lightness and the red colouration prized in Australian markets. [ABSTRACT FROM AUTHOR]

Ozone (O3) dissolved in seawater (ODS) was evaluated, as an egg disinfectant, on the spawn of captive gilthead sea bream, Sparus aurata, brood stock. Four contact times (CT) were tested (0.6, 1.2, 2.4 and 4.8 mg min L−1) where CT was calculated by multiplying the dissolved O3 concentration (0.3 mg L−1) by different exposure periods (2, 4, 8, 16 min). There was also a disinfected seawater treatment that contained no O3 or derived compounds (CT 0) and an untreated seawater control. All ODS treatments reduced egg surface bacterial counts to zero, which was significantly ( P<0.05) lower than the CT 0 and the control groups (194 and 1320 plate−1 respectively). Nevertheless, the hatching rate was high in the control and the CT treatments 0, 0.6 and 1.2 (88.7%, 87.3%, 89.5% and 83.7% respectively) while eggs exposed to a CT 2.4 and 4.8 hatched poorly (36.5% and 20.4% respectively), which was likely due, at least in part, to larvae unable to break the egg chorion successfully. Swim-bladder inflation was significantly higher in the ODS groups (>97%) compared with the control and CT 0 treatments (ca. 70%). The results suggest that a 2-min exposure of eggs to 0.3 mg O3 L−1 of ODS (CT 0.6) would improve current protocols in marine larviculture. [ABSTRACT FROM AUTHOR]

Ontogenic development of some digestive enzymes (proteases, amylase and lipase) in common pandora Pagellus erythrinus larva was assayed during larval development. The green-water technique was employed for larval rearing, and whole-body homogenates were used for enzymatic assays in triplicate. Important alterations in specific activities of all digestive enzymes measured during the period of this study were mostly related to metamorphosis and weaning. Mouth opening was observed on day 3 at 2.23±0.01 mm total length synchronously with the first determination of trypsin and chymotrypsin activities. After this date, the specific activities of these slightly increased until 25 days after hatching (DAH), respectively, and then slightly decreased and changed. The pattern determined for pepsin was strongly related to stomach formation on day 25 at 9.72±2.3 mm total length and a sharp increase was found until 30 DAH and then a slight decrease was measured from this date until the end of the experiment. Both amylase and lipase were measured for the first time on days 2 and 4, respectively, and also the specific activities of these showed similar patterns during the first week of the study. Then, slight variations were observed until 30 DAH and while lipase-specific activity had declined, an increase in the specific activity of amylase was found until the end of the experiment. Finally, it is thought that the variations observed in the specific activity in the profile of digestive enzymes were related to either metamorphosis such as formation of stomach (25 DAH) or to changes in characteristics of food (30 DAH). The pattern of development of the main digestive enzymes found in P. erythrinus is similar to that described in other Sparid species. [ABSTRACT FROM AUTHOR]

An experiment was conducted to evaluate the effects of dietary composition on apparent digestibility coefficients of protein, fat and carbohydrate of gilthead sea bream. In addition α-amylase and proteolytic activities were measured in the digestive tract of fish, held at 20±1°C. Six experimental diets were formulated containing approximately 40%, 45% and 50% protein, 11% and 21% fat and a starch level which fluctuated from 14% to 36%. Fish having an average weight of 100–130 g were used, fed at 1.5% of their body weight daily, and digestibility was measured using an indirect method. Enzyme activities were measured in the digestive tract of fish, fed diets containing a combination of 40%, 50% protein with 11%, 21% fat at 0.5, 5, 10, 24 h after a single meal. Starch digestibility was reduced with its level in the diet. It also negatively affected fat digestibility as well as protein digestibility, the last only at the high fat level. Dietary fat level had a negative effect on starch and protein digestibility. Fat affected also strongly α-amylase levels in the digestive tract, while its effect on protease activity was of smaller magnitude. These results indicate that digestive enzyme activities and nutrient digestibility values are affected by dietary composition, carbohydrates and fat indicating the strongest effect. [ABSTRACT FROM AUTHOR]

Two experiments were carried out to determine the apparent crude protein (CP), organic matter (OM), fat and gross energy (GE) digestibility coefficients (ADCs) of several protein and energy sources (ingredients) for Australian snapper using the indirect method of determination and collection of faeces by passive settlement. The first experiment determined ADCs for one level of fishmeal (500 g kg−1 diet), three levels of extruded wheat (200, 300 or 400 g kg−1 diet) and two levels of fish oil (150 or 250 g kg−1 diet). The second experiment determined ADCs for two levels each of meat meal or poultry meal (300 or 500 g kg−1 diet), one level each of haemoglobin powder or blood meal (150 g kg−1 diet) and one level each of solvent extracted soybean meal or a low-allergenic, cold-pressed soybean meal (300 g kg−1 diet). Similar ingredients and where appropriate, different inclusion levels were compared using one- or two-way analysis of variance (anova). Fishmeal was almost completely digested and ADC values ranged between 94.3% and 99.2%. Fish oil was also well digested, with ADC values ranging between 97.6% and 106.0% and was not significantly affected by inclusion level. Linear regression analysis indicated that there was no relationship between the inclusion level of extruded wheat and either CP (ADCs ranged from 100.1% to 105.4%) or fat digestibility (ADCs ranged from 89.1% to 104.4%). However, there was a significant negative linear relationship between the inclusion level of extruded wheat and GE digestibility (GEADC=86.51−0.031× inclusion level;R2=0.49). Two-wayanovaindicated that CP, OM and GE ADCs of poultry meal (i.e. 85.9%, 89.7% and 91.3% respectively) were significantly higher than those determined for meat meal (i.e. 63.8%, 63.4% and 71.3% respectively), but ADCs were not affected by inclusion level or the interaction between inclusion level and ingredient type. The fat digestibility coefficients of meat and poultry meal were not significantly different (ADCs ranged from 92.3% to 95.0%). The CP digestibility of haemoglobin powder (95.1%) was significantly higher than that of ring-dried blood meal (81.6%), but there was no difference between the digestibility of OM (77.0%) or GE (80.4%) from these products. There was no difference between the CP (88.9%), OM (56.9%) and GE (65.6%) digestibility of the solvent extracted soybean meal and the low-allergenic, cold-pressed soybean meal. These coefficients will be useful in formulating both practical and research-based diets for this species. [ABSTRACT FROM AUTHOR]

Vertebral deformities in red sea bream, Pagrus major, remain serious obstacles to the improvement of seedling quality for its aquaculture. However, the causalities of the deformities remain unclear and prevention methods have not yet been established. In this paper, oxygen deficiency during somitogenesis was demonstrated to cause centrum defects (formerly called fused vertebrae in many cases), which are the major vertebral deformity in cultured red sea bream. An induction experiment of centrum defects was conducted by placing fertilized red sea bream eggs under low dissolved oxygen conditions (10.3–16.6%). The low oxygen treatment was carried out for five different developmental stages of embryo: two-cell stage to blastula stage; gastrula stage; three to 10 somites stage; 11–17 somites stage and 18–24 somites stage. Oxygen deficiency during somitogenesis induced a high incidence of centrum defects. In contrast, it hardly induced centrum defects during the other stages. The dissolved oxygen concentration in the rearing water should be carefully regulated for fertilized eggs, especially during somitogenesis to reduce the incidence of vertebral deformities in the red sea bream. [ABSTRACT FROM AUTHOR]

This study assessed the nutrient and energy digestibility of a variety of canola protein products that were produced by processing canola meal under different conditions, using the red seabream, Pagrus auratus. The test canola protein products included solvent-extracted canola meal, expeller-extracted canola meal alone or subjected to one of two different heat treatments (120 or 150°C for 30 min), and expeller meal further processed to produce a canola protein concentrate (CPC). Solvent-extracted soybean meal was also included in the study as a reference ingredient. Daily feed intake and blood thyroid hormone levels over the experimental period were also examined. The total digestible protein content of the expeller- and solvent-extracted canola meals was 356 and 358 g per kg dry matter (g kg DM−1) respectively. The total digestible energy content of the expeller- and solvent-extracted canola meals was 14.23 and 8.60 MJ kg−1 respectively. The organic matter digestibilities of the solvent-extracted canola meal were poorer than noted for the expeller- and solvent-extracted soybean meal. Notably, the two sources of canola meals used in this study (solvent and expeller meals) did not cause problems with declining feed intakes or changes to blood levels of thyroid hormones when included in the diets of the fish at a 30% level, and the diets were fed over a 3-week period. The preparation of a CPC resulted in gains in total digestible energy, but a reduction in the amount of total digestible protein, relative to the expeller canola meal from which it was produced. However, the protein concentrating process marginally reduced the relative digestible value of the protein content. Heating expeller meal at 120 or 150°C for 30 min resulted in progressive reductions of all nutrient and energy digestibilities. [ABSTRACT FROM AUTHOR]

This study examined the biological value of expeller- and solvent-extracted canola meals when included in the diets of juvenile red seabream. Notably, the test and reference diets in this study were prepared to be protein (300 g kg−1 DM) and energy (16.5 MJ kg−1 DM) limiting. Test diets were prepared, in which canola meal provided either 20%, 40% or 60% of the total dietary digestible protein. To minimize the influence of compensatory feed intake, all diets were pair-fed to the fish on restricted basis. Positive and negative controls were also included as treatments in the study to demonstrate that the diets were protein limiting and also to demonstrate the relative value of the highest inclusion levels of each test ingredient. The canola meals, either expeller- or solvent-extracted, were found to be nutritionally useful in diets for red seabream. Both ingredients were of similar value to that of the soybean meal when included on an equivalent digestible protein basis. No significant differences in weight gain, survival, FCR, N retention, energy retention or the apparent biological value of the N content were observed among any of the groups receiving the test or reference diets. A few significant differences were observed among some of the test and reference diets with regard to the apparent biological value of their energy content, although no consistent pattern was evident. The positive control treatment supported significantly superior growth and food utilization by the fish relative to all other treatments. The negative control treatment resulted in significantly poorer growth and food utilization by the fish relative to all other treatments. On a relative basis, there were no declines in fish performance between the highest inclusion levels of the expeller- and solvent-extracted canola meals or the soybean meal. Hence, the fish in this study obtained equivalent nutritional value from these ingredients, on a digestible basis, to that of the fishmeal in the reference diet. [ABSTRACT FROM AUTHOR]

Vertebral deformities were investigated in cultured red sea bream, Pagrus major. In the field, deformities in seedlings were categorized and their incidence was calculated. In the laboratory, the symptoms of major vertebral deformities were examined morphologically using radiographs and by making transparent skeletal specimens. The internal structure of deformed vertebrae was examined histologically. The shortened body condition had the highest incidence (0.9–8.3%) of all deformities in the seedlings. In individuals with the shortened body condition, the ratio of trunk and caudal part length to body height was smaller. These fish had skeletal anomalies in the vertebrae, mainly centrum defects (64.3%) or undersized centrums (25.2%). The specimens with centrum defects had a characteristic anomaly in the vertebrae, with plural pairs of neural and haemal spines on a single centrum. This anomaly was frequently observed in the posterior abdominal vertebrae. The internal skeletal structure of such abnormal centrums was basically the same as that of normal centrums. In all the specimens with undersized centrums, both the centrum length and diameter were shorter than normal except for the first and second centrum, and urostyle. [ABSTRACT FROM AUTHOR]

Cultured red porgy Pagrus pagrus (L.) males ( n=6) were sampled every 2 weeks for milt, in order to monitor changes in sperm quality parameters during a whole spawning period. On 11 January 2001, 60% of the fish were spermiating, increasing to 100% in mid-February and dropping to 30% by mid-April. Sperm density showed a slight increasing trend, with mean values ranging between 8.6 and 23.7×109 spermatozoa mL−1. Sperm motility percentage exhibited a significant improvement during the spawning season (analysis of variance ( anova) P=0.0001). The duration of forward motility for the major part of the monitoring period ranged between 2 and 4 min. Red porgy spermatozoa maintained their viability for many days after whole storage of milt at 4°C. During the monitoring period there were significant changes in the mean duration of sperm survival after cold storage, ranging from 5 to 12 days. The total volume of expressible milt was maximal on 28 March, increasing from a mean value of 1.7 mL to 5.3 mL kg−1. Milt production of captive-reared red porgy does not appear to be limiting, when compared with the volume of expressible milt produced by other cultured marine fishes. [ABSTRACT FROM AUTHOR]

In order to clarify whether taurine is an essential element for larval and juvenile marine finfish, the taurine and cystathionine contents of Japanese flounder, Paralichthys olivaceus, and red sea bream, Pagrus major, in the early life stages were measured. Initially, Japanese flounder larvae just after hatching, and larvae and juveniles having a total length (TL) of 11, 16, 26 and 75 mm were collected from a seedling production pond. The taurine content in the body decreased rapidly after 11 mm TL and remained low until the fish reached a TL of 75 mm. By contrast, the variations in cystathionine content were opposite to that of taurine. Mysids, which are fed to Japanese flounder until 100 mm TL, under natural condition have 7-8 times higher taurine contents than commercial diets. Fish fed mysid also have about 10 times higher taurine content in the body compared with fish fed a commercial diet. Larval red sea bream were fed a microparticle diet with or without added taurine during a 20-day feeding experiment (until 23 days after hatching). The taurine content in larval red sea bream decreased immediately after hatching. However, when the fish were fed a microparticle diet containing a high taurine content, together with rotifers, the fish had a high amount of taurine in the whole body. These results indicate that cystathionine is converted from methionine, but it cannot be synthesized to taurine. This experiment suggested that taurine might be an essential nutrient for larval and juvenile marine finfish. [ABSTRACT FROM AUTHOR]

Abstract The influence of stocking density and feeding regime on the growth of red porgy was studied during winter and spring 1997. Fish were held in 500-L tanks at densities of either 50 or 100 fish per tank, and were fed by means of self-feeders under 6 h restricted (day or night) or free-access feeding regimes. Fish were tagged individually, and weight gain was recorded by individual weighing every second week over an 8-week period during each season. In winter, growth was influenced by feeding time. Fish tended to grow best when fed without restriction and worst when fed at night, although differences were not significant when tank means were compared. Stocking density was influential in the spring trial. Fish stocked at low density and feeding freely grew better than high-density fish that fed either freely or at night. The division of fish into three size classes revealed that, within each treatment, no differences occurred among classes, but growth of fish belonging to the same class was influenced by rearing conditions. No significant differences were found among feeding regimes in terms of the coefficients of weight variation ratio (CV[sub f]:CV[sub i]) and feed efficiency. [ABSTRACT FROM AUTHOR]

Studies the effect of fasting and refeeding on growth and body composition of red porgy, Pagrus pagrus. Biological responses during fasting and refeeding; Compensatory growth in fishes deprived of food; Changes caused by fasting in proportion to body chemical components.

Two growth trials were conducted to evaluate the nutritional quality of several soybean products as constituents in diets for the gilthead sea bream, Sparus aurata (L.). In a preliminary experiment, the fish were fed six diets containing different levels of solvent extracted soybean meal as a replacement for white fishmeal at four substitution levels; 10, 20, 30 and 40% of the fishmeal protein component. The diets supported less growth as the inclusion of soybean meal increased. However, significant reductions in growth were apparent at the 30% substitution level. All growth parameters followed the same trend. In the second experiment, six diets with 35% of the total protein contributed from differently processed soybean meals were tested. The products included three industrial full-fat meals heat processed for different periods, a solvent extracted meal and a soya protein concentrate. Protein digestibility coefficients were measured for all the experimental diets. All growth parameters of the fish fed the underheated full-fat meal, solvent extracted meal and soya concentrate were significantly lower than the control group. Protein digestibility coefficients were similar with no statistical differences (P < 0.05). [ABSTRACT FROM AUTHOR]