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1.
An 8‐week feeding trial was conducted to evaluate the optimum dietary protein to lipid ratio (P/L) for Starry flounder Platichthys stellatus (30.7 ± 0.7 g initial weight). Nine fishmeal‐based diets with three protein levels (40%, 45% and 50%) and three lipid levels (8%, 11% and 14%) were fed to 30 fish in triplicate. Results showed that the growth performance was affected by dietary P/L ratio significantly, and the best weight gain rate, specific growth rate and feed conversion ratio were appeared at fish fed P45L14 and P50L11 diets. Apparent digestibility coefficient of protein was increased with increasing dietary lipid, but lipid digestibility was decreased by dietary lipid. Lipid deposition in tissues was increased with increasing dietary lipid at each protein level and was higher for the lower protein diets. In liver, the per cent of both eicosapentaenoic acid and docosahexaenoic acid were increased by dietary protein. High dietary protein level (50%) at high lipid level (14%) increased arachidonic acid significantly. Aspartate aminotransferase and alanine aminotransferase were affected significantly by dietary P/L ratios. High density lipoprotein cholesterol and total cholesterol of 45% protein groups were significantly higher than others. The study revealed that the optimum dietary protein to lipid ratio for starry flounder was P45L14 or P50L11, or P/E ratios were 25.49 and 27.70 mg protein kJ?1 gross energy respectively.  相似文献   

2.
In this study, two growth trials were conducted to evaluate the effect of dietary protein and lipid levels on growth and feed utilization of white sea bream (Diplodus sargus) juveniles. For the first trial, five diets were formulated to contain 120 g kg?1 lipid and increasing levels of protein, ranging from 400 to 600 g kg?1. Two additional diets were formulated with 400 and 600 g kg?1 protein and 180 g kg?1 lipids. The diets were fed to apparent visual satiety to duplicate groups of fish with a mean weight of 1.5 g for 10 weeks. For the second growth trial, four diets were formulated to contain 120 g kg?1 lipid and 380–520 g kg?1 protein. Two additional diets were formulated with 380 and 520 g kg?1 protein and 180 g kg?1 lipids. The diets were fed to apparent visual satiety to triplicate groups of fish with a mean weight of 41 g for 12 weeks. At the end of both trials, there were no growth differences among groups independent of the dietary protein content. In the first trial, growth was negatively correlated to dietary lipid levels. No significant differences of feed intake were detected among groups in both trials, but a direct correlation between feed efficiency and dietary protein level was observed. Protein efficiency ratio and nitrogen (N) retention (% N intake) significantly decreased with the increase of dietary protein levels. In both trials, energy retention (% energy intake) was highest in groups fed on diets with the highest protein‐to‐energy (P/E) ratio. At the end of both trials, no significant differences in whole‐body composition were observed among groups. Specific activity of enzymes involved in amino acid catabolism [aspartate aminotransferase (AST), alanine aminotransferase (ALT) and glutamate dehydrogenase (GDH)] showed no significant differences with dietary protein level in both trials. Nevertheless, in the first trial, a significantly lower GDH activity was observed in fish fed with higher dietary lipid levels. No differences were found for specific activity of the lipogenic enzymes, fatty aid synthetase and glucose‐6‐phosphate dehydrogenase, in the second trial. Results of this study indicate that a diet with a protein level of 380–420 g kg?1 and a P/E ratio of 20 g protein MJ?1 satisfies the growth requirements of D. sargus juveniles. Also, within the range tested, no evidence of protein sparing by dietary lipids seems to occur.  相似文献   

3.
An 84‐day feeding trial was conducted to study the effect of different levels of dietary protein, 250 (P25), 300 (P30), 350 (P35), 400 (P40) and 450 g (P45) kg?1 dry matter (DM) on growth, feed intake, feed utilization and carcass composition of bagrid catfish Horabagrus brachysoma fingerlings. Triplicate groups of fingerlings with mean initial body weight of 2.2 g were fed the experimental diets twice daily, till satiation, in 150‐L tanks supplied with flow‐through freshwater. Daily dry matter intake by the fingerlings decreased significantly (P < 0.05) when fed P25 diet, containing 250 g protein kg?1. The highest body weight gain, specific growth rate (SGR) and protein efficiency ratio (PER), and the lowest feed conversion ratio (FCR) were observed in fish fed 350 g protein kg?1 diet. The fish fed with P45 diet had the lowest (P < 0.05) carcass lipid content. The polynomial regression analysis indicates that H. brachysoma fingerlings require 391 g dietary crude protein kg?1 diet.  相似文献   

4.
Six test diets with protein levels varying from 250 to 500 g kg?1 were fed to six triplicate groups of summerling (initial weight: 1.56 g) and seven test diets with protein levels varying from 200 to 500 g kg?1 were fed to seven triplicate groups of winterling (initial weight: 9.49 g) for 8 weeks. Weight gain (WG) and feed efficiency (FE) of summerling significantly increased with increasing dietary protein levels from 250 to 350 g kg?1 and slightly declined, but without statistical significance at a dietary protein level of 400 g kg?1, then further significantly decreased with increasing protein levels to 450 and 500 g kg?1; WG of winterling increased significantly with increasing dietary protein levels from 200 to 300 g kg?1 (P < 0.05), and above this level, WG had a tendency to decrease with increasing dietary protein levels. Winterling fed diets with 300 and 400 g kg?1 of dietary protein had significantly higher FE than those fed other diets. WG data analysis by quadratic regressions showed that the optimum dietary protein levels required for the maximum growth of summerling and winterling were 374 and 355 g kg?1 of dry diet respectively. Protein efficiency ratio of both summerling and winterling negatively correlated with levels of dietary protein. The whole body moisture, protein, lipid and ash of summerling after being fed various test diets for 8 weeks were significantly different among treatments (P < 0.05). The whole body moisture and fat of winterling were also significantly affected by dietary protein levels (P < 0.05), while the whole body protein and ash of winterling were not (P > 0.05).  相似文献   

5.
Because of the high costs associated with feed inputs, as well as increased concern about waste production on fish farms, there is considerable interest in developing growout diets which are both cost effective and low polluting. In two 12‐week growth trials, the response of subadult red drum, Sciaenops ocellatus, fed either a diet of 440 or 360 g protein kg?1 diet (44% or 36%) with varying E:P ratios were tested. In the first experiment, five diets containing 440 g protein kg?1 diet and one diet containing 360 g protein kg?1 diet (reference) were offered to red drum (mean initial weight of 186 g). The five test diets contained 83, 103, 123, 143, and 163 g lipid kg?1 diet, resulting in E:P ratios ranging from 34.3 to 38.9 kJ g protein–1. In experiment 2, five diets providing 360 g protein kg?1 diet and one diet containing 440 g protein kg?1 diet (reference) were offered to red drum (mean initial weight of 145 g). Dietary lipid levels included 83, 123, and 163 g lipid kg?1 diet, and dietary carbohydrate was diluted with 10% and 20% non‐nutritive bulk filler in two of the diets to result in E:P ratios ranging from 34.5 to 46.7 kJ g protein–1. In experiment 1, no significant differences in mean final weight, mean weight gain, feed efficiency, protein conversion efficiency or hepatosomatic index were observed between the five test diets providing 440 g protein kg?1 diet. Intraperitoneal fat generally increased with increasing dietary lipid. The results of experiment 2 indicate that amongst the test diets with 360 g protein kg?1 diet, mean final weight, mean weight gain, feed efficiency, protein conversion efficiency and hepatosomatic index were not significantly different. Intraperitoneal fat significantly increased with increasing dietary lipid. In both experiments, fish offered diets with 440 g protein kg?1 diet produced significantly higher growth and FE values as compared to fish receiving diets containing 360 g protein kg?1 diet. This study indicated that subadult red drum are tolerant of shifts in E:P ratios and utilize a wide range of dietary lipid and carbohydrate without compromising growth.  相似文献   

6.
A study was undertaken to determine the dietary protein level for optimal growth performance and body composition of juvenile Senegalese sole. Five experimental extruded diets were formulated to contain increasing levels of protein [430, 480, 530, 570 and 600 g kg?1 dry matter (DM)] and a constant lipid level, ranging from 100 to 130 g kg?1 DM. Triplicate groups of 35 sole (initial body weight: 11.9 ± 0.5 g) were grown over 84 days in 60‐L tanks supplied with recirculated seawater. Fish were fed by means of automatic feeders in eight meals per day. At the start and end of the trial, whole‐body samples were withdrawn for proximate composition analysis. At the end of 84 days of experimental feeding, daily weight gain and specific growth rate in fish fed diets P43 and P48 were significantly lower than those found in fish fed higher protein level diets (P53, P57 and P59). Similarly, feed efficiency was also significantly lower in fish fed diet P43 than in fish fed all other dietary treatments. Sole juveniles fed lower protein level diets (P43 and P48) showed a significantly lower protein content than fish fed the higher dietary protein level treatments (P53, P57 and P60). Changes within the tested dietary protein levels did not affect significantly protein productive value or total nitrogen (N) losses in fish. However, daily N gain was significantly higher (P < 0.05) in fish fed diets P53 and P60 than in fish fed the lowest protein level diet (P43). Data from the present study indicate that diets for juvenile Senegalese sole should include at least 53% crude protein to maintain a good overall growth performance. Based on a second‐order polynomial regression model, the daily crude protein requirement for maximum whole‐body N gain as estimated here for Senegalese sole juveniles was 6.43 g kg?1 body weight day?1 which corresponds to a value of 1.03 g N intake kg?1 body weight day?1. If the present data are expressed on a dietary crude protein concentration basis, the allowance for maximum protein accretion (N gain) would be met by a diet containing a crude protein level of 600 g kg?1.  相似文献   

7.
The approximate levels of dietary protein and energy that would sustain good growth and survival of the mangrove red snapper Lutjanus argentimaculatus (Forsskal) were determined in two feeding experiments. In the preliminary experiment, six fish meal‐based diets were formulated to contain three protein levels (35%, 42.5% and 50%) and two lipid levels (6% and 12%) for each protein, with dietary energy ranging from 14.6 MJ kg?1 to 20.5 MJ kg?1. The protein to energy (P/E) ratios of diets ranged from 20.6 mg protein kJ?1 to 27.5 mg protein kJ?1. Diets were fed for 100 days to triplicate groups of snappers with an average initial weight of 24.8 ± 0.4 g. No significant interaction between different levels of protein and lipid was observed. Survival rates (93.8% to 100%), feed conversion ratios (FCR) (2.61–3.06) and condition factors (K) were not affected by different dietary treatments. Regardless of lipid level, fish fed 50% protein diets had a significantly higher specific growth rate (SGR) than fish fed the 35% protein diets, but not compared with the 42.5% diets (P < 0.05). Increasing lipid to 12% in all protein levels resulted in no improvement in growth over the 6% level. Fish body moisture did not vary while lipid levels based on dry matter were high (27.9% to 33.7%). Snapper appear to require more than 40% dietary protein and a high dietary energy level for good growth. In the second experiment, fish (21.1 ± 0.1 g) in four replicate groups were fed for 94 days with three diets (39%, 44% and 49% protein with P/E ratios of 21.1, 23.3 and 25.5 mg protein kJ?1 respectively) containing similar dietary energy levels of about 19 MJ kg?1. Average final weight, SGR and FCR were significantly higher in diets containing 44% and 49% protein diets (P > 0.05). There were no differences in survival rates, protein efficiency ratio (PER) and nutrient composition of snapper flesh. All fish had fatty livers. Results indicated that the diet containing 44% protein with a P/E ratio of 23.3 mg protein kJ?1 was optimum for snapper growth under the experimental conditions used in the study.  相似文献   

8.
A 74‐day trial was undertaken to evaluate the effects of temperature (16 and 22 °C) and dietary protein/lipid ratio on the performance of juvenile Senegalese sole (mean body weight: 6.4 g). Four experimental diets were formulated to contain two protein levels (550 g kg?1 and 450 g kg?1) combined with two lipid levels (80 g kg?1 and 160 g kg?1). Growth was higher at 22 °C and within each temperature in fish fed diets 55P8L and 45P16L. Feed efficiency, N retention (% NI) and energy retention (% EI) were higher at 22 and at both temperatures in fish fed diet 55P8L. Temperature affected whole‐body composition, with dry matter, protein, lipid and energy being higher and ash lower in fish kept at higher temperature. Independently of temperature, whole‐body lipid, energy and ash were higher and protein was lower in fish fed the high‐lipid diets. Visceral and hepatosomatic indices were not affected by diet composition but were higher in fish kept at 16 °C. Liver glycogen and lipid contents and activities of glutamate dehydrogenase, alanine and aspartate aminotransferases were not affected by diet or water temperature. Malic enzyme (ME) and glucose 6‐phosphate dehydrogenase activities were higher in fish fed the low‐lipid diets. ME activity was higher at lower temperature. In conclusion, increasing water temperature from 16 to 22 °C improves growth and feed efficiency of Senegalese sole juveniles; regardless of water temperature, the diet with 550 g kg?1 protein and 80 g kg?1 lipid promoted the best growth and feed efficiency.  相似文献   

9.
A study was undertaken to determine the effect of dietary lipid level on growth, feed efficiency and body chemical composition of juvenile grass carp. Seven isonitrogenous diets (400 g kg?1 crude protein) containing seven dietary lipid level (0, 20, 40, 60, 80, 100 and 120 g kg?1 dry matter) were fed to triplicate groups of 40 fish with initial weight 6.52 g, for 70 days. No obvious and assured essential fatty acid deficiency symptom appeared in fish fed the lipid‐free diet. Excess dietary lipid level (100 and 120 g kg?1) resulted in decreased feed intake. The best growth performance and feed utilization was observed in fish fed 20–40 g kg?1 dietary lipid. The fish fed a lipid‐free diet had the lowest protein efficiency and protein retention. Growth performance and feed utilization increased with the increasing dietary lipid levels up to 40 g kg?1 dietary lipid. Higher dietary level (above 40 g kg?1) made growth performance and feed utilization decrease and no protein sparing effect was observed. Lipid retention decreased as dietary lipid level increased. Mesenteric fat index (MFI) increased, hepatosomatic index (HSI) decreased with dietary lipid level. The increased MFI and simultaneous decrease lipid retention can be explained by differences in growth. The effect of dietary lipid levels on the chemical composition of tissues was significant only for whole body and muscle. The excess lipid content of liver in all groups was regarded as a slight symptom of fatty liver, which was partly identified by microscopic structural study and lower plasma lipid indexes, comparing to the initial plasma data. In conclusion, grass carp is a fish with low energy requirement and excess dietary lipid level should be avoided.  相似文献   

10.
Six isonitrogenous (390 g kg?1) and isoenergetic (16.2 kJ g?1) diets with varying carbohydrate : lipid (CHO : L) ratios (202.5–1.74), were fed to triplicate groups of 25 fish in indoor recirculation system. Over 8‐week‐growth trial, best weight gain (WG), specific growth rate, feed conversion ratio, protein efficiency ratio and protein production value (P < 0.05) were observed in fish‐fed diets with CHO : L ratio of 7.5. Fish fed either the lowest (1.7) or highest (202.5) CHO : L ratio tended to produce lower (P < 0.05) growth and feed conversion efficiencies. The values of viscerosomatic index, hepatosomatic index and intraperitoneal fat ratio increased as dietary CHO : L ratios decreased. There were no significant differences in whole body and liver crude protein among dietary treatments. Whole body and liver lipid increased as CHO : L ratios decreased. Plasma cholesterol and triacylglyceride levels increased linearly as dietary CHO : L ratios decreased. Activities of glucokinase and pyruvate kinase were stimulated by elevated levels of dietary carbohydrate; however, activities of lipase (LPS) and alkaline phosphatase were stimulated by elevated levels of dietary lipid. Based on a second‐order polynomial regression analysis of WG against dietary carbohydrate and lipid levels, 275 g kg?1 of carbohydrate and 59 g kg?1 of lipid, corresponding to a CHO : L ratio of 4.7, in a diet holding 390 g kg?1 of crude protein and 16.3 kJ g?1 of gross energy, proved to be optimal for grass carp. These results indicated that utilization of dietary lipid and carbohydrate was moderate in grass carp, but the fish were a little more capable of utilizing lipid compared with carbohydrate.  相似文献   

11.
A 3 × 3 factorial experiment was conducted to determine proper levels of dietary protein, lipid and dextrin for juvenile flounder. Nine experimental diets were formulated to contain three protein levels (410, 460 and 510 g kg?1) and three lipid levels (60, 130 and 190 g kg?1) with corresponding dextrin levels (250, 150 and 50 g kg?1). Triplicate groups of fish (8.9 ± 0.4 g) were hand‐fed the diets to apparent satiation for 7 weeks in flow‐through system. Specific growth rate was the highest in fish fed the 510 g kg?1 protein diet with 60 g kg?1 lipid, and was not significantly different from that of fish fed 460 g kg?1 protein diet with 60 g kg?1 lipid. Feed efficiency ratio tended to increase as dietary protein level increased. The feed efficiency ratio of fish fed the 510 g kg?1 protein diets with 60–190 g kg?1 lipid levels was not significantly different from that of fish fed 460 g kg?1 protein diet with 60 g kg?1 lipid. Daily feed intake tended to decrease with increasing dietary lipid level at each protein level. Daily protein intake increased with increasing dietary protein level at 60 g kg?1 lipid level. Hepatosomatic index and visceralsomatic index increased with increasing dietary lipid level at each protein level. The lipid contents of liver, viscera and whole body, and concentrations of plasma total cholesterol and triglyceride increased with increasing dietary lipid levels; however, no significant difference was observed in the contents of dorsal muscle lipid. The results of this study suggest that the diet containing 460–510 g kg?1 protein with low lipid level (60 g kg?1) is optimal for growth and efficient feed utilization of juvenile flounder.  相似文献   

12.
An 8‐week feeding trial was conducted to investigate the optimum dietary protein and lipid levels for growth, feed utilization and body composition of Pseudobagrus ussuriensis fingerlings (initial weight: 3.40 ± 0.01 g). Twelve diets containing four protein levels (350, 400, 450 and 500 g kg?1 crude protein) and three lipid levels (50, 100 and 150 g kg?1 crude lipid) were formulated. Fish were randomly allotted to 36 aquaria (1.0 × 0.5 × 0.8 m) with 25 fish to each glass aquarium. Fish were fed twice daily (08:00 and 16:00) to apparent satiation. The results showed that weight gain and specific growth rate (SGR) decreased with increasing dietary lipid level from 50 to 150 g kg?1 at the same dietary protein level. Fish fed the diets containing 150 g kg?1 lipid exhibited higher feed conversion ratio (P < 0.05), lower protein efficiency ratio (PER) and nitrogen retention efficiency (NRE) relative to fish fed the diet containing 50 and 100 g kg?1 lipid. Weight gain and SGR significantly increased with increasing dietary protein from 350 to 450 g kg?1 at the same dietary lipid level, and even a little decline in growth with the further increase in dietary protein to 500 g kg?1. Daily feed intake, NRE and PER were significantly affected by both dietary protein and lipid levels (P < 0.05) and tended to decrease with increasing dietary protein and lipid levels. Whole‐body protein content increased as protein levels increased and lipid levels decreased. Whole‐body lipid and muscle lipid content increased with increasing dietary lipid level, and decreased with increasing dietary protein at each lipid level. There was no significant difference in condition factor and viscerosomatic index among fish fed the diets. Hepatosomatic index was affected by dietary lipid level (P < 0.05), and increased with increasing dietary lipid level at the same protein level. These results suggest that the diet containing 450 g kg?1 protein and 50 g kg?1 lipid with a P/E ratio of 29.1 mg protein kJ?1 is optimal for growth and feed utilization of P. ussuriensis fingerlings under the experimental conditions used in the study.  相似文献   

13.
Two feeding trials were conducted to determine the minimum dietary protein level producing maximum growth, and the optimum protein to energy ratio in diets for red porgy (Pagrus pagrus) fingerlings, respectively. In the first trial, six isoenergetic diets were formulated with protein levels ranging from 400 to 650 g kg?1 in increments of 50 g kg?1, and fed for 11 weeks to 2.8 g average initial weight fish. Weight gain, specific growth rate and feed efficiency were significantly higher with diets containing higher protein levels, when compared with dietary levels below 500 g kg?1. The highest protein efficiency ratios were obtained in fish fed 500 g kg?1 dietary protein. The minimum dietary protein level producing maximum fish growth was found to be 500 g kg?1. In the second trial, 15 g average initial weight fish were fed for 12 weeks, six diets containing three different lipid levels (100, 150 and 200 g kg?1) combined with two protein levels (450 and 500 g kg?1). Weight gain values increased when dietary lipids increased from 100 to 150 g kg?1, with a further decrease for 200 g kg?1 lipids in diets; the lowest fish growth being supported by 200 g kg?1 dietary lipids. Fish growth was significantly higher when dietary protein increased from 450 to 500 g kg?1. There was no evidence of a protein‐sparing effect of dietary lipids. Liver protein and lipid contents were low when compared with other fish species. All diet assayed produced high liver glycogen accumulation. The recommended protein and lipid levels in diets for red porgy fingerlings were 500 and 150 g kg?1, respectively.  相似文献   

14.
In order to evaluate the effects of dietary protein and lipid levels on the growth, feed utilization and body composition of Heterotis niloticus fingerlings, a factorial experiment with three replicates was conducted. Six experimental diets containing three crude protein levels (28%, 32% and 36%) and two crude lipid levels (6% and 13%) were tested. Heterotis niloticus (2.34 g) were fed with the diets to apparent satiation, twice a day. For 56 days, weight gain (WG), specific growth rate (SGR), feed efficiency (FE) and protein retention (PR) were significantly affected by dietary protein and dietary lipid levels respectively (P<0.01). The highest WG, SGR and FE were observed for fingerlings fed the diet containing 36% protein and 6% lipid, but no significance difference was found between groups fed with the following diets: P28L13 (28% protein and 13% lipid), P32L6, P32L13 and P36L13. A significant interaction between dietary protein and lipid was observed for WG, SGR, FE and PR. The whole‐body protein, lipid, moisture and ash content were not significantly affected by dietary lipid levels, but body protein and lipid content were significantly affected by dietary protein. The dietary protein‐sparing effect was clearly demonstrated when the dietary energy of lipid increased from 17 to 19.6 kJ g?1 at 28% crude protein on H. niloticus.  相似文献   

15.
A growth experiment was conducted to investigate effect of dietary protein to energy ratios on growth and body composition of juvenile Myxocyprinus asiaticus (initial mean weight: 10.04 ± 0.53 g, mean ± SD). Nine practical diets were formulated to contain three protein levels (340, 390 and 440 g kg?1), each with three lipid levels (60, 100 and 140 g kg?1), in order to produce a range of P/E ratios (from 22.4 to 32.8 mg protein kJ?1). Each diet was randomly assigned to triplicate groups of 20 fish in 400‐L indoors flow‐through circular fibre glass tanks provided with sand‐filtered aerated freshwater. The results showed that the growth was significantly affected by dietary P/E ratio (P < 0.05). Fish fed the diets with 440 g kg?1 protein (100 and 140 g kg?1 lipid, P/E ratio of 31.43 and 29.22 mg protein kJ?1) had the highest specific growth rates (SGR) (2.16 and 2.27% day?1, respectively). However, fish fed the diet with 390 g kg?1 protein and 140 g kg?1 lipid showed comparable growth (2.01% day?1), and had higher protein efficiency ratio (PER), protein productive value (PPV) and energy retention (ER) than other groups (P < 0.05). No significant differences in survival were found among dietary treatments. Carcass lipid content was positively correlated with dietary lipid level, but irrespective of protein level and inversely correlated with carcass moisture content. Carcass protein contents increased with increasing dietary lipid at each protein level. The white muscle and liver composition showed that lipid increased with increasing dietary lipid level (P < 0.05). Dietary protein concentrations had significant effect on condition factor (CF), hepatosomatic index (HSI) and viscerosomatic index (VSI) (P < 0.05). However, dietary lipid concentrations had no significant effect on CF, HSI (P > 0.05). Based on these observations, 440 g kg?1 protein with lipid from 100 to 140 g kg?1 (P/E ratio of 29.22 to 31.43 mg protein kJ?1) seemed to meet minimum requirement for optimal growth and feed utilization, and lipid could cause protein‐sparing effect in diets for juvenile Chinese sucker.  相似文献   

16.
Dietary protein requirement for young turbot (Scophthalmus maximus L.)   总被引：2，自引：0，他引：2  
This study was conducted to determine the optimum dietary protein level for young (an initial weight of 89 g) turbot, Scophthalmus maximus L. Duplicate groups of the fish were fed the five isoenergetic diets containing the various protein levels ranging from 290 to 570 g kg?1 diet for 45 days. Survival was not affected by dietary protein level. Weight gain and feed efficiency were improved with dietary protein level up to 490 g kg?1 diet. Dietary protein requirement of young turbot using the broken‐line model was estimated to be 494 g kg?1 diet based on weight gain response. Protein efficiency ratio was not influenced by dietary protein level. The highest protein retention was obtained from the fish fed the 490 g protein kg?1 diet. Proximate composition of the fish was not significantly affected by dietary protein level. In considering these results, it was concluded that the 494 g protein kg?1 diet with 100 g lipid kg?1 diet (15 MJ kg?1 diet) provided optimal growth of young turbot under these experimental conditions.  相似文献   

17.
The present study investigated the effect of varying dietary protein‐to‐lipid ratios (P/L) on growth performance and body composition of pike perch (Sander lucioperca) fingerlings with an initial body weight of 1.35–1.40 g. Triplicate groups were reared during 56 days in recirculation systems and fed six experimental diets containing three dietary levels of lipid (90, 130, 170 g kg?1 of dry matter, d.m.) combined with two levels of dietary protein (470, 540 g kg?1 d.m.). During the experimental period the fixed feeding rates decreased from 10% to 5% of the total fish biomass per day. In contrast to previous results obtained with this species, the present study clearly demonstrated the occurrence of protein sparing effect. The best results for feed conversation ratio and specific growth rates were obtained in the treatments containing highest lipid level: diet 3 (P/L 47/17) and diet 6 (P/L 53/17). The d.m. and crude lipid contents of pike perch whole body increased in direct proportion of the dietary lipid levels. No difference was observed on crude protein and ash content among the treatments. Increasing hepatosomatic index at highest dietary lipid level suggested a limited lipid utilization of percids.  相似文献   

18.
An 8‐week feeding trial was conducted to estimate the optimum dietary protein to energy (P/E) ratio in juvenile olive flounder Paralichthys olivaceus. Eight experimental diets were formulated with two energy levels and four protein levels at each energy level. Two energy levels of 12.5 and 16.7 kJ g?1 diets were included at crude protein (CP) levels of 25%, 30%, 35% and 45% with 12.5 kJ g?1, and CP levels of 35%, 45%, 50% and 60% with 16.7 kJ g?1. After 1 week of the conditioning period, fish initially averaging 8.1±0.08 g (mean±SD) were randomly distributed into the aquarium as groups of 15 fish. Each diet was fed on a dry‐matter basis to fish in three randomly selected aquariums at a rate of 3–5% of total wet body weight per day for 8 weeks. After 8 weeks of the feeding trial, weight gain (WG), feed efficiency ratio and specific growth rate of fish fed 45% CP with 16.7 kJ g?1 energy diet were significantly higher than those from the other dietary treatments (P<0.05). WG of fish fed 12.5 kJ g?1 energy diets increased with the increase of dietary protein levels. However, WG of fish fed 16.7 kJ g?1 energy diets increased with the increase of dietary protein levels up to 45% CP and then decreased when fish fed 50% and 60% CP diets. Both dietary protein and energy affected protein retention efficiency and energy retention efficiency. Haemoglobin (Hb) of fish fed 35% and 45% CP diets with 12.5 kJ g?1 energy were significantly high and not different from Hb of fish fed 45% and 50% CP diets with 16.7 kJ g?1 energy. Haematocrit of fish fed 45% CP diet with 16.7 kJ g?1 energy was significantly higher than those from fish fed 25% and 30% CP diets with 12.5 kJ g?1 energy (P< 0.05). Based on the results of this experiment, we concluded that the optimum dietary P/E ratio was 27.5 mg protein kJ?1 with diet containing 45% CP and 16.7 kJ g?1 energy in juvenile olive flounder.  相似文献   

19.
An 8‐week growth trial was conducted using a 2 × 3 factorial design to evaluate the effect of substitution of fishmeal (FM) by rendered animal protein blend [APB, comprised of 400 g kg?1 poultry by‐product meal, 350 g kg?1 meat and bone meal, 200 g kg?1 hydrolysed feather meal (HFM) and 50 g kg?1 spray‐dried blood meal] in diets of Siberian sturgeon, Acipenser baerii Brandt. Two isoenergetic control diets were formulated to contain two different protein levels [high‐protein control (400 g kg?1), with 483 g kg?1 of FM] and [low‐protein control (360 g kg?1), with 400 g kg?1 of FM]. At each protein level, dietary FM protein was replaced by APB at 75% and 100% levels and supplemented with crystallized essential amino acid under ideal protein concept. The six diets were named as HC, HAPB75, HAPB100, LC, LAPB75 and LAPB100, respectively. No significant differences were found in weight gain rate (WGR) and specific growth rate (SGR), but fish fed with the low‐protein diets showed higher feed intake and feed conversion ratio. Plasma growth hormone and insulin‐like growth factors I of each group were not significantly different (P > 0.05). The whole‐body composition and liver composition were not affected by dietary protein levels, replacement or their interaction. Muscle protein and lipid contents of fish fed with diet LAPB100 were significantly lower than those of HC group. Digestibility of nitrogen (N) and phosphorus (P) were reduced with higher APB inclusion levels, but productive N and P values of all groups were not different. Lower N and P intake induced lower nutrients losses (P < 0.05). The results suggested that dietary protein level could be reduced to 360 g kg?1 from 400 g kg?1 without affecting WGR or SGR and significantly reduced nutrients lose. Furthermore, dietary FM protein can be totally replaced by APB in feed formulation either at 400 g kg?1 or at 360 g kg?1 protein level.  相似文献   

20.
An 11‐week feeding trial was conducted to evaluate the effects of dietary protein and/or energy levels on growth, feed efficiency and proximate composition of juvenile (average weight: 21.5 g) common carp (Cyprinus carpio L.) fed various diets based on constant daily protein input. Five experimental diets were prepared. One group of diets (diets 1, 2 and 3) contained three crude protein (P) levels (35%, 40% and 45%) with a constant gross energy (GE) of 3.8 kcal g?1 diet. The second group of diets (diets 4 and 5) were formulated to contain a GE of 4.3 or 4.9 kcal g?1 diet and 40% or 45% protein levels, respectively, where GE/P was constant at 10.8 kcal g?1 protein. Fish receiving diet 1 served as the control; they were hand‐fed to visual satiety. Feed allowance for diets 2 and 4 was 87.5% of the control. Feed allowance for fish receiving diets 3 and 5 was 77.8% of the control. Thus, all tanks received the same daily protein input. When gross energy in the diets was constant, 3.8 kcal g?1 diet, weight gain of fish fed diet 2 at 87.5% satiation was significantly higher than that of fish fed diet 3 at 77.8% of satiation. When the GE/P in the diets was constant, 10.8 kcal g?1 protein, weight gain of fish fed diet 1 was significantly higher than that of fish fed diet 5 at 77.8% satiation. The feed efficiency ratio (FER) for diets 2–5 was significantly higher than for diet 1 at constant GE and GE/P, and this improved linearly as dietary protein levels increased. The protein efficiency ratio (PER) for diet 2 was significantly higher than for diet 3 at constant GE. However, PER was not significantly different at constant GE/P. Protein retention of fish fed diet 2 was significantly higher than that of fish fed diet 3 at constant GE. Protein retention of fish linearly decreased at constant GE/P. The energy efficiency ratios (EER) for diets 2 and 3 were significantly higher than for diet 1 at constant GE. Moisture and protein contents of the whole body of fish were not significantly different at constant GE, but they decreased linearly at constant GE/P. The lipid content of fish fed diet 1 was significantly lower than that of fish fed diet 2 at constant GE, and body lipid content linearly increased at constant GE/P. These results indicate that growth and feed efficiency for common carp fed a 40% protein diet with 3.8 kcal g?1 diet GE at 87.5% satiation rate was superior to those for the fish fed either a 35% protein diet with 3.8 kcal g?1 diet GE at 100% satiation rate or a 45% protein diet with either a 3.8 or 4.9 kcal g?1 diet GE at 77.8% satiation rate.  相似文献   

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