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1.
The present study aimed to determine the effect of feeding time on growth and nitrogen excretion in juvenile sole. An 84‐day growth trial was conducted, in which food was supplied to three triplicate groups of juvenile Senegalese sole (3 g wet weight) at different schedules – diurnal, nocturnal and mixed. At the end of the growth trial, ammonia and urea excretion was assessed during a 24 h cycle. Improved growth (1.3% vs. 0.9% day?1, specific growth rate), higher nitrogen retention (0.35 vs. 0.27 g N kg?1 day?1), lower ammonia excretion (209 vs. 272 mg N‐NH4 kg?1 day?1) and lower total nitrogen excretion (278 vs. 352 mg N kg?1 day?1) were found in daytime‐fed fish compared with night‐fed fish. Fish in the mixed feeding regime showed intermediate values of ammonia and total nitrogen excretion, but did not differ from day‐fed fish regarding the other parameters. Results indicate that juvenile sole at a period of their life cycle appear to use more efficiently dietary protein for somatic growth under a diurnal than under a nocturnal feeding regime. This suggest that at least during a time‐window in the juvenile rearing a diurnal feeding regime might be more effective in the production of this species.  相似文献   

2.
This study determined the digestibility of nitrogen and phosphorus, and the excretion rate of different‐sized groups of milkfish fed a commercial diet, a SEAFDEC formulated diet or lab‐lab (natural food‐based diet). Fish (31.2–263.0 g) were stocked in 12 units of 300‐L fibreglass tanks filled with aerated seawater. The postprandial total ammonia‐nitrogen (TAN) and phosphate (PO4‐P) excretion of fish were estimated from changes in TAN and PO4‐P concentrations in water for 24 h. Digestibility was determined from the nitrogen, phosphorus and Cr2O3 content of the diets, and pooled faeces after the fish had been fed diets marked with chromic oxide. TAN excretion rate (mg TAN kg?1 fish day?1) was significantly lowest (P < 0.05) in medium to very big fish fed the lab‐lab diet (60.8–124.4) and highest in small and medium fish fed the SEAFDEC diet (333.3–331.6) and small fish fed the commercial diet (280.1). Regardless of size, fish fed lab‐lab excreted (mg PO4‐P kg?1 fish day?1) significantly lower PO4‐P (36.2) but did not differ with fish fed the commercial diet (64.8). Excretion rates decreased exponentially as fish weight increased but positively increased with feed ration. Excretion pattern of milkfish revealed two peaks: the first peak occurred 6 h after feeding and the second peak at 18 h for TAN and 21 h for PO4‐P, coinciding with the start of the daylight hours. TAN and PO4‐P excretion accounted for 20.5–34.6% of total N consumed and 18.7–42.6% of P consumed respectively. Approximately 27.9–42.5% of N consumed and 47.2–58.5% of P consumed were lost as faeces. Total nutrient losses were lower using the lab‐lab diet (0.31 g N and 0.14 g P kg?1 fish) compared with the formulated diets (0.47–0.48 g N and 0.17–0.19 g P kg?1 fish); the losses decreased per kg of fish as fish size increased. Results suggest that the diet and size of fish influence wastage of N and P to the environment with greater losses in small fish and when artificial diets are used. Such measurements will provide valuable information for the preparation of N and P budgets for milkfish in grow‐out systems.  相似文献   

3.
The growth efficiency of juvenile Atlantic halibut, Hippoglossus hippoglossus (L.), was investigated by comparing wet weight specific growth rates (SGRs) over 28 days with protein synthesis rates measured using a non-invasive stable isotope (15N) tracer technique. A diet containing 15N-labelled protein was fed at a single meal and individual feed intake was measured by X-ray radiography to allow calculation of the amount of N consumed. Excreted ammonia and urea were collected from each fish and the ratio of 15N to 14N was used to calculate rates of protein synthesis. Peak rates of ammonia excretion occurred 12 h post-feeding. Rates of urea excretion did not change after feeding and remained relatively constant over the 48-h measurement period. Urea accounted for 17% of the measured nitrogen excretion and showed no enrichment with N. Mean protein growth rates were 1.31 ± 0.06% day?1, while whole animal fractional rates of protein synthesis were 2.02 ± 0.24% day?1. The mean protein synthesis retention efficiency was 77.41 ± 9.09%, which is higher than that recorded for most other teleosts. This suggests that halibut have a relatively low cost, high growth efficiency growth strategy.  相似文献   

4.
Four experiments were conducted to investigate the effects of feeding frequency on growth of juvenile Atlantic halibut, Hippoglossus hippoglossus L. Fish (22–75 g) fed three (3 ×) or five times per day (5 × day?1) under constant light and temperature (13±1°C) consumed significantly more feed than fish fed 1 × day?1 but by the end of the experiment only fish fed 5 × day?1 were heavier and had greater specific growth rates (SGR). Under simulated winter conditions (9L:15D, 5±1°C), halibut (～300 g) fed every other day consumed more feed, had a greater SGR and final weight compared with fish fed every third day. Feed conversion ratios were not different among treatment groups in any of the experiments. These results suggest that growth rates may be improved by feeding juvenile halibut more than 1 × day?1.  相似文献   

5.
Oxygen consumption, carbon dioxide excretion and nitrogen excretion from 2 kg Atlantic salmon Salmo salar L. were studied at land-based outdoor tanks, throughout a 10 day period. Fish were fed six feed rations (0 [fasting fish], 0.15, 0.30, 0.45, 0.60 and 0.75% BW day-1) of commercially extruded dry feed at two provision regimes: between 07.00-09.00 h and 19.00–21.00 h (periodic feeding); and between 07.00-21.00 h (continuous feeding). Fish were acclimatized to the feeding regime for 5 days prior to the start of the experiment. From days 5 to 10 of the study, oxygen consumption was measured automatically every 15 min. During day 10, carbon dioxide excretion, ammonia and urea excretion were measured hourly throughout a 24 h period. During the experiment, the water temperature and salinity were 8.5C and 33.5 ppt, respectively. Significant linear relationships between feed ration and metabolic rates were evident. Increased feed ration influenced oxygen consumption, carbon dioxide excretion, ammonia and urea excretion, ammonia quotient and the respiration quotient, proportionally. The two feed provision regimes caused the establishment of different daily rhythms in metabolic excretion. Only small differences in total daily excretion were however recorded for each feed ration. Ammonia and respiratory quotient results clearly showed that fish became more dependent on fat oxidation as an energy source, when feed was restricted.  相似文献   

6.
A 28‐week feeding trial was conducted in concrete tanks with Nile tilapia, Oreochromis niloticus (L.) with an average initial weight and length of 61.9±6.03 (g fish?1) and 17.6±0.45 (cm fish?1), respectively, to examine the effect of two protein levels and three feeding levels (% body weight (BW) day?1) on growth performance, production traits and body composition. Twelve 4‐m3 concrete tanks (2 × 2 × 1.25 m, long, width and height) were each stocked with 100 fish and fed diets containing either 25% or 30% crude protein at rates of 1%, 2% and 3% BW daily (2 × 3 factorial experiment). The results revealed that there was no significant increase in growth rate with increasing dietary protein levels, whereas there was significant increase in growth rate with increasing feeding levels (P≤0.05). The same trend was also observed for mean BW (g), mean body length (cm), production rate (kg m?3), specific growth rate (SGR % day?1), feed conversion ratio (FCR), condition factor (K) and survival rate (%). The best final mean BW (g), final mean body length (cm), SGR (% day?1), FCR, K, production rate (kg m?3) and survival rate (%) were recorded in groups of fish fed with 25% dietary protein at the 2% feeding level. Whole fish fat and energy contents were not significantly influenced (P>0.05) by protein levels and feeding levels. Protein and ash contents were significantly (P≤0.05) influenced by feeding level, but not by dietary protein level. Economic evaluation indicated that dietary protein 25% (diet A) at the 2% BW day?1 feeding level was the most cost‐effective and affordable feed strategy for farmers. We conclude that a 25% protein diet fed at 2% BW day?1 is recommended for adult Nile tilapia reared in concrete tanks.  相似文献   

7.
A study was conducted to examine the use of corn distillers’ by‐products in diets and the effects of additional dietary fat on channel catfish, Ictalurus punctatus, performance. Juvenile channel catfish (initial weight: 12.6 g per fish) were stocked in flow‐through aquaria and fed one of six practical diets for 9 weeks. Fish fed the control + fat diet consumed more diet and had higher feed efficiency ratio (FER) than fish fed the control diet, but weight gain was not significantly different between fish fed these two diets. Fish fed the diet containing 300 g kg?1 distillers dried grains with solubles (DDGS) consumed more diet and gained more weight, but had similar FER compared with fish fed the control + fat diet. The diet containing 200 g kg?1 high‐protein distillers grains (HPDDG) resulted in similar diet consumption, weight gain and FER as the control + fat diet. Fish fed the diet containing 100 g kg?1 distillers solubles (DS) consumed more diet, but had similar weight gain and FER compared with fish fed the 300 g kg?1 DDGS diet. The presence of distillers solubles in the diet (300 g kg?1 DDGS, 100 g kg?1 DS, 100 g kg?1 EDS diets) appears to increase diet consumption, weight gain, and FER over the control diets with or without additional fat.  相似文献   

8.
Two feeding trials were carried out to determine the optimum feeding rates in juvenile olive flounder, Paralichthys olivaceus, at the optimum rearing temperature. Fish averaging 5.0 ± 0.11 g (mean ± SD) in experiment 1 and 20.2 ± 0.54 g (mean ± SD) in experiment 2 were fed a commercial diet at the feeding rates of 0%, 3.0%, 4.0%, 4.25%, 4.5% and 4.75% body weight (BW) day?1 and satiation (5.52% BW day?1) in experiment 1 and 0%, 1.0%, 2.0%, 3.0% and 3.5% BW day?1 and satiation (4.12% BW day?1) in experiment 2 at 20 ± 1 °C. Both feeding trials lasted for 2 weeks. Results from experiment 1 indicated that weight gain (WG) and specific growth rate (SGR) of fish fed to satiation were significantly higher than those of fish fed at other feeding rates while feed efficiency (FE) and protein efficiency ratio (PER) of fish fed at 4.25% BW day?1 were significantly higher than those of fish fed to satiation and fish fed at 3.0% BW day?1 (P < 0.05). In experiment 2 WG, SGR and PER leveled out after the feeding rate of 3.5% BW day?1 whereas FE reached a plateau at 3.0% BW day?1. anova of FE indicated that the optimum feeding rates in 5.0 and 20 g juvenile olive flounder could be 4.25% and 3.0% BW day?1, respectively. Broken line analysis of WG suggested the optimum feeding rates of 5.17% and 3.47% BW day?1 in 5.0 and 20 g fish, respectively. Therefore, these results indicated that the optimum feeding rates could be >4.25 but <5.17% BW day?1 for 5.0 g, and it could be >3.0 but <3.47% BW day?1 for 20 g size of juvenile olive flounder at the optimum rearing temperature.  相似文献   

9.
Empirical data on ammonia excretion rates were compiled from several published and unpublished growth studies on post-smolt Atlantic salmon, Salmo salar L. Fish in all studies were fed to satiation with commercially produced high-energy diets (ME = 18–19 MJ kg-1) with a protein content of 40–45%. About 35 ± 3% (mean SE) of the nitrogen supplied to fish was excreted as total ammonia (TAN = NH3-N + NH4+-N). The results of a linear regression analysis of N intake to N excretion demonstrated, however, that TAN excretion rates could be divided into two components: TANexcretion [g N kg fish-1 day-1] = 0.036 + 0.26 Nintake [g N kg fish-1 day-1]. The intercept of the regression equation indicates that the endogenous TAN excretion rates in post-smolts could be estimated as 36 mg TAN kg fish-1 day-1, and about 26% of the nitrogen supplied to the fish was excreted postprandially. This postprandial TAN excretion was lower than that from other salmonid species fed low-energy diets. The daily maximum TAN excretion rate was about 43% higher than daily mean values, which agree with several studies. The ammonia quotient (A.Q.) measured was independent of the nitrogen supplied, and was calculated as 0.112. The outputs from the present model were compared to those from other ammonia excretion models.  相似文献   

10.
An experiment was conducted to determine effects of feeding levels on growth performance, feed utilization, nutrient deposition, body composition and apparent digestibility coefficients (ADCs) of nutrients for juvenile Chinese sucker (initial weight, 11.77±0.22 g). Chinese sucker were fed a practical diet from 0% (starvation) to 4.0% (at 0.5% increments) body weight (bw) day?1 for 8 weeks. The results showed that growth performance, feed utilization, nutrient deposition, body composition and ADCs of dry matter, protein and energy were significantly (P<0.05) affected by feeding levels. Survival was the lowest for the starvation group. Final mean body weight, growth rate, thermal‐unit growth coefficient (TGC) increased with feeding rate from 0% to 3.0% bw day?1 (P<0.05) and showed no significant differences above the level (P>0.05). Feed conversion rate was significantly lower at a feeding level of 2.5% bw day?1 than above and below the level (P<0.05). Protein efficiency ratio was markedly highest at the 2.5% bw day?1 ration level (P<0.05). Fish fed at the feeding level (1.0% bw day?1), which represented a maintenance ration (energy gain was less than 2.27 kJ fish?1 day?1), showed positive protein deposition but negative lipid deposition. This indicates that fish fed a maintenance ration mobilize body lipid reserve to support protein deposition. Lipid contents of whole body, muscle and liver increased with increasing feeding rates from 0.5% to 3.0% bw day?1 and showed no significant differences above the level (P>0.05). Protein contents of whole‐body composition increased with feeding rate from 0.5 to 3.0% bw day?1 (P<0.05) and showed no significant differences above the level (P>0.05), whereas muscle and liver remained relatively stable with the different ration amount with the exception of fish fed a ration of 0.5% bw day?1, at which Chinese sucker possessed significantly lower body protein concentration (P<0.05). The ADCs of dry matter, protein and energy decreased with increasing feeding levels from 0.5% to 3.0% bw day?1 and then remained relatively constant over the level. Based on the broken‐line regression analysis using WG data, the optimum and maintenance feeding levels for Chinese sucker were 3.10% bw day?1 and 0.45% bw day?1 respectively.  相似文献   

11.
The effect of diet on the growth and survival in captivity of the octopus Enteroctopus megalocyathus Gould, 1852 was researched to establish culture potential. This is one of two commercially important octopus species that inhabit the Chilean coast. A positive energy budget, averaging 678 J day?1 g of dry weight (dw), was recorded in specimens maintained in tanks and fed ad libitum on a diet of three species of crustacean decapods. On the other hand, the energy budget of octopus specimens fed on the mussel Mytilus chilensis (Hupé) was negative, averaging ?250.90 J day?1 g dw?1. Ingestion rates varied between diets (t=46.45; d.f.=18; P<0.001), but no variations were recorded in energy loss resulting from metabolism (t=0.67; d.f.=16; P>0.05) or ammonia excretion (t=1.39; d.f.=16; P>0.05). An average instantaneous growth rate (IGR) of between 1.96% and 0.49% was recorded in specimens fed on crustaceans, depending on the size of the octopus and the period of time. The IGR in specimens fed on mussels was ?0.32±0.05. The IGR of specimens fed on crustaceans and maintained in suspended systems was 1.36±0.9%. The mean mortality with crustacean and mussel diets was 11.07±5.5% and 74±1% respectively. The results indicate that E. megalocyathus can survive and grow in captivity, both in tanks and in suspended systems, when fed on a diet of crustaceans.  相似文献   

12.
The study was conducted to determine the optimum stocking density for rearing tilapia. Oreochromis spilurus (Günther), fingerlings in tanks during winter using warm (21-26°C) underground sea water (37%o). Seawater-acclimated fingerlings with mean weight of 2 g were stocked in eighteen 400-1 fibreglass tanks at 750 and 1000 fish m?3. Fish were fed at the rates of 2.5, 3.0 and 3.5% day?1 of the fish biomass. After 83 days, the mean individual daily weight gain was significantly higher (P < 0.028) at stocking of 750 fish m?3 than at 1000 fish m?3. Feed conversion ratio was significantly higher at stocking of 1000 fish m?3 than at 750 fish m?3 and at feeding rate of 3.5% day1 than at 2.5% day?1. However, because no significant differences were observed on survival rates between the two stocking densities and among feeding rates, it is recommended that the stocking density of 1000 fish m?3 and a feeding rate of 2.5% day?1 be used for optimum production of tilapia fingerlings in tanks during winter using warm underground sea water.  相似文献   

13.
To develop a feeding strategy for the Australian freshwater fish silver perch (Bidyanus bidyanus Mitchell), a series of eight experiments was done in 1 m3 cages in an aerated, earthen pond to determine the effects of feeding rate (% body weight) and feeding frequency (no. of feeds day?1) on the growth and feed conversion ratio (FCR) of fingerlings and larger fish under ambient water temperatures over the range 13.8–30.6°C. Fish were fed extruded pellets of a silver perch diet containing 34% digestible protein and 14 MJ kg?1 digestible energy. Commercial silver perch farmers were consulted about feeding practices for large fish (>500 g) and at water temperatures below 12°C, and winter feeding practices for other warmwater species were used to complete the strategy. In the feeding experiments, growth and FCR increased with increasing feeding rates to a level above which only FCR increased. Optimal feeding rates and frequencies were those which resulted in maximal growth, while minimizing effort (feeding frequency) and FCR. The highest feeding frequency required for maximal growth, including that of small fingerlings was twice (2 ×) daily, and the optimal feeding rates varied with water temperature and size of fish. The optimal daily regimes were: small fingerlings (initial mean weight, 2.0 g) 7.5% 2 × at a mean temperature of 23.3°C; fingerlings (14.9–27.7 g) 7.5% 2 × at 27.1°C, 5.0% 2 × at 23.7°C and 2.0% 1 × at 16.8°C; and large silver perch (162.5–510.6 g) 0.5% 1 × daily or 1.0% on alternate days at 15.6°C, 1.0% 1 × at 17.3°C, 3.0% 2 × at 24.1°C and 2.0% 2 × at 27.9°C. It is suggested that regimes of 0.5% 1 × daily for fingerlings (<50 g) and 0.5% 1 × on alternate days for larger fish are used at temperatures of 9–12°C, and 0.5% 3 days week?1 and 0.5% 1 day week?1 for fingerlings and larger fish, respectively, at 6–9°C. Feed inputs should not exceed 150 kg ha?1 day?1 in ponds less than 0.3 ha and 100 kg ha?1 day?1 in larger ponds. Our research has established a feeding strategy for silver perch based on restricted rations.  相似文献   

14.
Year-1 channel catfish, Ictalurus punctatus (Rafinesque) (average initial weight, 48 g) were fed diets containing 240 g kg?1, 300 g kg?1, or 360 g kg?1 dietary protein with 0 or 20 mg kg?1 ractopamine to satiation and diets containing 240 g kg?1 and 360 g kg?1 protein with 0 or 20 mg kg?1 ractopamine at a restricted rate (60% of satiation) in aquaria at 29 ± 2°C for 8 weeks. Fish fed ractopamine at the 360 g kg?1 protein level gained significantly more weight than controls when fed to satiation but not when the ration was restricted. Fish fed ractopamine at the 240 g kg?1 protein level did not gain more weight than the controls at satiation or restricted feeding. Fish fed ractopamine in the diet containing 300 g kg?1 protein gained significantly more weight than controls when fed to satiation. Ractopamine caused no significant differences in feed conversion at the 240 g kg?1 or 360 g kg?1 protein levels with restricted or satiation feeding. Muscle fat decreased when ractopamine was fed at all dietary protein levels and at both feeding rates. Muscle protein increased with ractopamine feeding in all treatments except the high-protein, satiation treatment. Weight gain response of year-1 channel catfish to ractopamine is dependent upon nutrient concentration of the diet and ration size; however, the effect of ractopamine on muscle composition of channel catfish is less dependent on nutrient concentration or amount of diet fed.  相似文献   

15.
Dietary protein requirement of white sea bream (Diplodus sargus) juveniles   总被引：1，自引：0，他引：1  
A trial was undertaken to estimate the protein requirement of white sea bream (Diplodus sargus). Five fish meal‐based diets were formulated to contain graded levels of protein (from 60 to 490 g kg?1). Each diet was assigned to triplicate groups of 25 fish with a mean individual body weight of 22 g. Fish fed the 60 g kg?1 protein diet lost weight during the trial, while growth improved in the other groups as dietary protein level increased up to 270–370 g kg?1. Feed efficiency improved as dietary protein level increased. Maximum protein efficiency ratio (PER) was observed with the 17% protein diet. N retention (NR) (% N intake) was not different among groups fed diets with 17% protein and above. Ammonia excretion (g kg?1ABW day?1) increased as dietary protein level increased, while no differences in urea excretion were noted. An exponential model was used to adjust specific growth rate and NR (g kg?1 day?1) to dietary protein level. Based on that model, dietary protein required for maximum retention was 330 g kg?1, while for maximum growth it was 270 g kg?1. On a wet weight basis, there were no differences in whole body composition of fish‐fed diets with 170 g kg?1 protein and above, except for the protein content, which was lower in group fed the 170 g kg?1 protein diet than the 490 g kg?1 protein diet. Specific activities of hepatic amino acid catabolism enzymes (glutamate dehydrogenase, alanine aminotransferase and aspartate aminotransferase) increased as dietary protein levels increased. There were no differences among groups in fatty acid synthetase and malyc enzyme but 6‐phosphate dehydrogenase (G6PDH) was significantly lower in fish fed the 60 g kg?1 protein diet than the 170 and 490 g kg?1 protein diets.  相似文献   

16.
The effects of feeding frequency (1, 2, 3, or 15 times daily) on oxygen consumption (OC, mg O2 kg−1 h−1) and ammonia excretion, (AE, mg TAN kg−1 h−1) of walleye (Stizostedion vitreum) are described. Walleye were reared at a practical culture density of 35·4 kg m−3 in a single-pass system at 23·2°C. Diurnal variation in metabolic rates were related to feeding, not to photoperiod. Minimum OC rates occurred 30 min before the first feeding of the day, which was the longest average time since the last feeding. Metabolic rates increased immediately after feeding. The maximum rates for OC were 36–49% higher than the minimum rates, and 14–22% higher than the 24-h mean rate. Maximum rates for AE were 137–409% higher than the minimum rates, and 39–87% higher than the mean rates. There was a highly significant difference in the mean metabolic rates related to feeding frequency. The mean OC rate for 1 feeding day−1 (222·0 mg O2 kg−1 h−1) was greater than the mean rates for 2, 3 and 15 feedings day−1. The OC rate for 1 feeding day−1 was 50·6% greater than the rate for 15 feedings day−1 (147·4 mg O2 kg−1 h−1), the lowest mean rate. Mean and maximum oxygen/feed ratio (OFR, kg O2 kg−1 feed fed day−1), varied inversely with feeding frequency. The mean ammonia/feed ratio (AFR) was similar for all but the 3 feedings day−1 treatment, but the maximum AFRs for 2 and 15 feedings day−1 were lower than the AFRs for 1 and 3 feedings day−1. AE was directly proportional to OC; the regression equations were highly significant, but specific for feeding frequency.  相似文献   

17.
The effects of stocking density and feeding levels on larval survival, growth rates, feed utilization efficiency and body composition of Nile tilapia (Oreochromis niloticus L.) fry were investigated in two consecutive experiments. In experiment 1, swimup fry (0.016 g average body weight) were stocked in 20‐L fibreglass tanks, in a closed, recirculating indoor system, at five stocking densities (3, 5, 10, 15 and 20 fry L?1) and fed a larval test diet (40% crude protein) to apparent satiation, three times a day, for 40 days. Fish survival, percentage weight gain and specific growth rate (% SGR) were negatively correlated with stocking density. The best performance was achieved at 3 fry L?1. However, no significant differences in growth parameters were found between 3 and 5 fry L?1. Body composition was not significantly affected by stocking density. In experiment 2, fry (0.016 g average body weight) were stocked at 5 fry L?1, and fed a larval test diet (40% crude protein) at six feeding levels (10%, 20%, 25%, 30% and 35% BW day?1) and to satiation, three times a day for 40 days. Fish growth rates and survival were extremely poor at 10% feeding level, and improved significantly with increasing feeding levels up to 30%, and levelled off with further increase in feeding levels. On the contrary, feed conversion ratio (FCR) and protein production value (PPV) were negatively correlated with feeding level. The lowest feeding level (10%) produced significantly lower body lipid and higher protein and ash than other feeding levels. The present results suggest that the optimum stocking density and feeding level of Nile tilapia fry are 5 fry L?1 and 30% per day respectively.  相似文献   

18.
A feeding experiment was conducted to investigate the effects of high dietary intake of vitamin E (supplied as dl ‐α‐tocopheryl acetate) and n‐3 highly unsaturated fatty acid (n‐3 HUFA) on the non‐specific immune response and disease resistance in Japanese flounder Paralichthys olivaceus. Nine practical diets were formulated to contain one of three levels of vitamin E namely, 0, 80 or 200 mg kg?1 (the total α‐tocopherol contents in the diets were 21, 97 and 213 mg kg?1 based on analysis), and at each vitamin E level with one of three n‐3 HUFA levels i.e. 0.5%, 1.5% or 2.0%. Each diet was randomly assigned to triplicate groups of Japanese flounder (initial body weight: 40.5±1.0 g, mean±SD) in a re‐circulation rearing system. Fish were fed twice daily to apparent satiation at 07:00 and 18:00 hours for 12 weeks. During the experimental period, water temperature was maintained at 18±1°C, salinity 31–35 g L?1, and pH 7.8–8.2. Dissolved oxygen was not less than 6 mg L?1, and there were negligible levels of free ammonia and nitrite. The results showed that the increase in dietary n‐3 HUFA from 0.5% to 1.0% significantly decreased muscle α‐tocopherol contents in fish‐fed diets with 21 and 97 mg α‐tocopherol kg?1 diet (P<0.05). In 1.0% HUFA groups, alternative complement pathway activity (ACH50) of fish fed the diet containing the 213 mg α‐tocopherol kg?1 diet was significantly higher than noted for fish fed the diet containing 97 mg α‐tocopherol kg?1 diet (P<0.05). Fish fed the diet with 213 mg α‐tocopherol kg?1 and 2.0% n‐3 HUFA had the highest lysozyme activity (131.7 U mL?1) among all the dietary treatments. Fish fed the diets containing 97 and 213 mg α‐tocopherol kg?1 with 1.0% n‐3 HUFA had significantly higher respiratory burst activity than those fed the diets containing 21 mg α‐tocopherol kg?1 with 0.5 and 1.0% n‐3 HUFA (P<0.05). In the disease resistance experiment, high intake of dietary vitamin E with 213 mg α‐tocopherol kg?1 significantly decreased cumulative mortality and delayed the days to first mortality after a 7‐day Edwardsiella tarda challenge (P<0.05). In addition, under the experimental conditions, dietary vitamin E and n‐3 HUFA had a synergistic effect on the non‐specific immune responses and disease resistance in Japanese flounder (P<0.05).  相似文献   

19.
A ten-week feeding trial was carried out to evaluate animal proteins, either alone or in combination (1:1:1), on the growth performances and economic benefit of climbing perch, Anabas testudineus. Four iso-proteinous (40%) diets were prepared, using fishmeal, protein concentrate, and meat and bone meal as major protein source in diets 1, 2 and 3, respectively, while diet 4 consisted of an equal proportion (1:1:1) of the above protein sources. Triplicate groups of fish (0.53 ± 0.02 g) were randomly stocked in 12 earthen ponds at a stocking density of 40,000 ha?1. Fish fed diet 4 had significantly (P < 0.05) higher percent weight gain and SGR % per day?1 compared to the fish fed diets 1, 2, or 3. Significantly higher apparent protein efficiency ratio (1.25) and lower apparent feed conversion ratio (2.00) were also observed in fish fed diet 4. Total yield (1,123 kg ha?1) and net profit (Tk. 116,569 ha?1) were also higher in fish fed diet 4. It can be concluded that the combination of fishmeal, protein concentrate, and meat and bone meal is more effective for climbing perch than any of the three protein sources alone.  相似文献   

20.
Four semi‐moist formulated feeds were supplied to Octopus vulgaris subadults (664 ± 70 g; 18.4 ± 0.7°C) in two different experiments. In the experiment #1, two diets were prepared with a new mixture of binders (gelatine 150 g kg?1, starch 100 g kg?1 and gum 50 g kg?1). The GEL15‐Squid and GEL15‐Hake feeds included 100 g kg?1 freeze‐dried squid (Todarodes sagittatus) or hake (Merluccius sp.) respectively. Both feeds showed low water disintegration rates at 24 h (13.6–15.0% dry weight). The specific feeding rate was higher in animals fed GEL15‐Hake (2.7%BW day?1), but the growth and feed efficiency were significantly better in animals fed GEL15‐Squid (1.4%BW day?1 and 61.2% respectively; P < 0.05). The proximate composition of the digestive gland, carcass and whole animals was similar. In the experiment #2, the GEL15‐Squid amino acid profile was improved by replacing 50 g kg?1 gelatine by 50 g kg?1 freeze‐dried squid (GEL10‐Squid) or freeze‐dried fish (GEL10‐Fish). These feeds showed higher water disintegration rates (31.7–36.3% dry weight). The feeding rates (2.2–2.3%BW day?1), growth (1.5%BW day?1) and feed efficiency were similar for both diets. Total lipids were higher in the digestive gland and whole animals fed GEL10‐Fish diet (P < 0.05). Future effort could be directed towards alternative binders that allow improve amino acid balance with a minimum gelatine content or even supplementation trials including essential amino acids.  相似文献   

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