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1.
A 30‐day feeding experiment was conducted to estimate the lysine requirement of large yellow croaker larvae (2.75 ± 0.11 mg). Six isonitrogenous (509.5–519.7 g kg?1 crude protein) and isoenergetic (22.3–22.5 kJ g?1 energy) microdiets containing graded levels of lysine·HCl ranging from 24.8 to 41.0 g kg?1 diet in placement of glycine and glutamic acid were formulated. Mixture of crystalline amino acids (MAA) was supplemented to simulate the amino acid (AA) profiles of whole body of this larva, except for lysine. The MAA and supplemented lysine for each diet were coated with tripalmitin. Triplicate groups of 3000 fish were fed to apparent satiation by hand eight times per day. The results showed that specific growth rate (SGR), survival, body composition and the specific activity of digestive enzymes were significantly affected by dietary lysine levels (P<0.05). The optimal dietary lysine requirements estimated by second‐order polynomial model based on SGR and survival were 33.7 (65.5 g kg?1 dietary protein) and 33.4 (64.9 g kg?1 dietary protein) g kg?1 dry diet respectively. The estimated requirements for the other essential AAs were calculated by A/E ratios of whole body AA profile of this larva based on lysine requirement.  相似文献   

2.
Toxicity of aflatoxin B1 (AFB1) was investigated in juvenile hybrid sturgeon Acipenser ruthenus ♂ × A. baeri♀, an important coldwater finfish farmed in China and other countries. Seven experimental diets (Diet A–G) containing different levels of AFB1 (0, 1, 5, 10, 20, 40 and 80 μg kg?1 diet) were fed to juvenile sturgeon weighing 10.53 ± 0.17 g kg?1 to determine its effect on survival, growth, feed consumption, hematocrit, liver histology as well as muscular and hepatic toxin accumulation. The experiment lasted for 35 days and was conducted in two periods of 25 and 10 days each. No external changes or unusual behaviour was observed in the fish fed diets with AFB1. Mortality was observed in fish fed with highest levels of AFB1 (80 μg kg?1– Diet G) from day 12 onwards. After 25 days, fish fed the diet of 80 μg AFB1 kg?1 showed significant lower survival (50 ± 5.77%) followed by those fed 40 μg AFB1 kg?1 diet (80 ± 5.77%) and 20 μg AFB1 kg?1 diet (86.66 ± 3.33%). No significant difference was observed in specific growth rate (SGR) or hepatosomatic index (HSI) between groups. Hematocrit was significantly higher in the fish fed the diet of highest AFB1. The fish were weighed at day 25 in some treatments (Diets F and G) because of high mortality. However, feeding was continued for another 10 days to observe mortality or behavioural changes if any in the other groups. After 35 days, survival in the fish fed Diet F (40 μg AFB1 kg?1) was 40% and those fed Diet E (20 μg AFB1 kg?1) was 36.2%. Significant histopathological changes including nuclear hypertrophy, hyperchromasia, extensive biliary hyperplasia, focal hepatocyte necrosis and presence of inflammatory cells were observed in the liver of fish fed high levels of aflatoxin (40 and 80 μg kg?1). AFB1 accumulation in fish muscle and liver increased with increased dietary AFB1 levels. It could be confirmed that 10 μg AFB1 kg?1 diet was the maximum allowable level in hybrid sturgeon diet.  相似文献   

3.
The effects of dietary calcium chloride (CaCl2) concentration on the growth, survival, moulting and body composition of Astacus leptodactylus were studied. Diets were prepared using supplementation of 0 (control), 30, 60 and 120 g kg?1 calcium chloride commercial trout larvae diet containing 50% protein and 12% lipid. Astacus leptodactylus larvae with an average total length of 22.0 ± 0.05 mm (TL) and weight of 0.53 ± 0.01 g obtained from eighteen ovigerous females collected from Seydisehir Sugla Dam lake in Konya, Turkey, were stocked in 0.2‐m2 aquariums at a rate of 50 crayfish m?2 and reared for 90 days. The experiments included four treatments (diets) with three replicates each. Calcium chloride exerted positive effects on growth, moulting frequency, feed efficiency and survival of narrow‐clawed crayfish. Crayfish fed with 60 g calcium kg?1 calcium chloride‐supplemented diet exhibited the highest weight gain and specific growth rate (SGR) but the lowest survival rate (63.3%) (P < 0.05). There were no significant differences (P > 0.05) in mean moisture (803.5 g kg?1) and protein content (177.0 g kg?1) in crayfish tail meat. However, lipid values were between 3.8 and 11.6 g kg?1 and significantly different among the diets (P < 0.05). Diet with 60 g kg?1 calcium chloride is recommended for the best growth of freshwater crayfish.  相似文献   

4.
A 10‐week feeding experiment was conducted to evaluate the effect of different protein to energy ratios on growth and body composition of juvenile Litopenaeus vannamei (initial average weight of 0.09 ± 0.002 g, mean ± SE). Twelve practical test diets were formulated to contain four protein levels (300, 340, 380 and 420 g kg?1) and three lipid levels (50, 75 and 100 g kg?1). Each diet was randomly fed to triplicate groups of 30 shrimps per tank (260 L). The water temperature was 28.5 ± 2 °C and the salinity was 28 ± 1 g L?1 during the experimental period. The results showed that the growth was significantly (P < 0.05) affected by dietary treatments. Shrimps fed the diets containing 300 g kg?1 protein showed the poorest growth. However, shrimp fed the 75 g kg?1 lipid diets had only slightly higher growth than that fed 50 g kg?1 lipid diets at the same dietary protein level, and even a little decline in growth with the further increase of dietary lipid to 100 g kg?1. Shrimp fed the diet with 420 g kg?1protein and 75 g kg?1 lipid had the highest specific growth rate. However, shrimp fed the diet with 340 g kg?1 protein and 75 g kg?1 lipid showed comparable growth, and had the highest protein efficiency ratio, energy retention and feed efficiency ratio among dietary treatments. Triglycerides and total cholesterol in the serum of shrimp increased with increasing dietary lipid level at the same dietary protein level. Body lipid and energy increased with increasing dietary lipid level irrespective of dietary protein. Results of the present study showed that the diet containing 340 g kg?1 protein and 75 g kg?1 lipid with digestible protein/digestible energy of 21.1 mg kJ?1 is optimum for L. vannamei, and the increase of dietary lipid level has not efficient protein‐sparing effect.  相似文献   

5.
Protein requirement of silver barb, Puntius gonionotus fingerlings   总被引：2，自引：0，他引：2  
Five iso‐energetic (15.05 MJ kg?1) semi‐purified diets with graded levels of crude protein, i.e. 200 (D‐1), 250 (D‐2), 300 (D‐3), 350 (D‐4) and 400 (D‐5) g kg?1 diet were fed to Puntius gonionotus fingerlings (average weight 0.88 ± 0.03 g) in triplicate groups (15 healthy fish per replicate) for a period of 90 days to determine the optimum protein requirement of the fish. Fifteen flow‐through cement tanks of 100‐L capacity with a flow rate of 0.5 L min?1 were used for rearing the fish. Specific growth rate (SGR), food conversion (food gain) ratio (FCR), nutrient digestibility and retention, digestive enzyme activity, RNA : DNA ratio and tissue composition were used as response parameters with respect to dietary protein levels and feed intake. The mean weight gains of fish after 90 days were 10.84 ± 0.27, 11.07 ± 0.12, 14.09 ± 0.20, 11.27 ± 0.12 and 10.91 ± 0.25 g for D‐1, D‐2, D‐3, D‐4 and D‐5, respectively. Maximum SGR (3.13 ± 0.02% per day), RNA : DNA ratio (10.09 ± 0.09), tissue protein content (160 ± 0.1 g kg?1 wet weight), protease activity (25.27 ± 0.47 μg of leucine liberated mg tissue per protein h?1 at 37 °C) and minimum FCR (1.60 ± 0.02) was found in D‐3 group fed with 300 g kg?1 protein level. All these parameters were negatively affected with the further increase in protein level in the diet. Digestibility of protein, lipid and energy was not affected because of variation in dietary protein levels and nitrogen intake of fish. Maximum energy retention (27.68 ± 0.12%) was recorded at 300 g kg?1 dietary crude protein fed group. However, using broken line regression analysis, the maximum growth was found to be at 317.7 g kg?1 dietary protein. Hence, it may be concluded that the protein requirement of P. gonionotus fingerling is 317.7 g kg?1 diet with a resultant P/E ratio of 21.1 g protein MJ?1.  相似文献   

6.
A total of 630 juvenile Chinese sucker, with an average initial weight of 1.72 ± 0.05 g, were fed seven diets for 56 days to study the effect of dietary methionine levels on growth, feed utilization, body composition and haematological parameters on juvenile Chinese sucker. Diet 1 using fish meal as the sole protein source and diets 2–7 using fish meal and fermented soybean meal as intact protein sources supplemented with crystalline amino acids contained six levels of l ‐methionine ranging from 6.4 to 18.9 g kg?1 of dry diet at a constant dietary cystine level of 3.7 g kg?1. Each diet was randomly assigned to three aquaria. Results indicated that the highest weight gain, specific growth rate (SGR), feed efficiency ratio, protein efficiency ratio and protein productive value occurred at 13.9 g methionine kg?1 diet among the methionine supplemented dietary groups, beyond which they showed declining tendency. The whole body and muscle protein contents of juvenile Chinese sucker were positively correlated with dietary methionine level, while muscle lipid content was negatively correlated with it. The total essential amino acids content of muscle was increased significantly with increasing dietary methionine level from 6.4 to 13.9 g kg?1 (P < 0.05). Apparent digestibility coefficients of dietary protein were significantly affected by dietary treatments. Serum protein, cholesterol and triacylglycerol increased with increasing dietary methionine levels, but showed a relatively lower value for fish fed the 18.9 g methionine kg?1 diet. Quadratic regression analysis of SGR against dietary methionine level indicated that optimal dietary methionine requirement for juvenile Chinese sucker was 14.1 g kg?1 of the diet in the presence of 3.7 g kg?1 cystine (corresponding to 32.0 g kg?1 of dietary protein on a dry‐weight basis).  相似文献   

7.
Two feeding experiments were conducted to investigate the effects of dietary inclusion of different plant ingredients on growth and body composition of juvenile sea cucumber. In the first experiment, three replicate groups of the sea cucumber (average weight of 1.5 ± 0.05 g) were fed one of the seven experimental diets containing Sargassum thunbergii (CON), Undaria (UND), Laminaria (LAM), Brassica oleracea L. var. capitata (BRA), fermented soybean (FSB), distillers dried grain (DDG) and rice straw powder (RIC) for 10 weeks. After the feeding trial, survival was not significantly different among the dietary treatments. Specific growth rate (SGR) of sea cucumber fed the FSB diet (0.73) was significantly higher than that of sea cucumber fed the other diets (P < 0.05), except for the DDG diet (0.64). The lowest SGR was observed in sea cucumber fed the CON diet (0.14). Based on the result of the first experiment, the second experiment was conducted to determine the proper level of dietary DDG for growth of juvenile sea cucumber. Three replicate groups of sea cucumber (average weight of 1.6 ± 0.02 g) were fed one of the five experimental diets containing different levels (g kg?1) of DDG (DDG0, DDG10, DDG20, DDG30 and DDG40) for 12 weeks. Survival was not significantly different among the treatments (P > 0.05). The best SGR was obtained in sea cucumber fed the DDG10 diet (10.1) and the value of sea cucumber fed the DDG40 diet (5.6) was the lowest (P < 0.05). The SGR of sea cucumber fed the DDG10 diet did not differ from that of sea cucumber fed the DDG20 diet (P > 0.05). Moisture, crude protein, crude lipid and ash contents of whole body in sea cucumber among the dietary treatments (P > 0.05) did not differ significantly at both experiments. Results of two feeding trial suggest that dietary inclusion with 100 g kg?1 FSB or 100–200 g kg?1 DDG may improve growth of juvenile sea cucumber, and especially DDG could be used as a good ingredient for the low‐cost feed formulation.  相似文献   

8.
A 10‐week feeding trial was conducted in a flow‐through system to determine dietary choline requirement for juvenile gibel carp (Carassius auratus gibelio) (5.5 ± 0.1 g). Purified basal diet was formulated using vitamin‐free casein as protein source. Choline chloride was supplemented to the basal diet to formulate seven diets containing 76.1, 163, 356, 969, 1457, 2024 and 4400 mg kg?1 choline. Dietary methionine was 0.58%, less than the requirement (0.69%). The results indicated that specific growth rate (SGR) was higher in the fish fed 2024 mg kg?1 diet than the control group. Feeding rate and feed efficiency were not significantly affected. Protein productive value increased as dietary choline increased from 76.1 to 2024 mg kg?1 diet and was lower in the fish fed the diet containing 4400 mg choline kg?1 diet. Serum high‐density lipoprotein cholesterol (HDL‐C) and total cholesterol significantly increased with increasing dietary choline up to 1457 mg kg?1, and no differences were found with further increase. Fish carcass fat contents decreased significantly with increased dietary choline. Hepatic lipid contents increased with dietary choline up to 1457 mg kg?1 and then decreased. Quadric regression of SGR and plasma HDL‐C indicted dietary choline requirement was 2500 and 2667 mg kg?1 diet, respectively.  相似文献   

9.
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   

10.
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   

11.
A grow‐out experiment was designed to determine the effect of different dietary protein, lipid levels and protein–energy (P:E) ratio on growth performance and feed utilization of the freshwater prawn, Macrobrachium rosenbergii post larvae (PL) culture in pond net enclosures (hapa, 3.75 m?3 each) for 12 weeks (84 days). The experimental treatments were assigned in triplicate. Six test diets were formulated to contain three different protein levels (300, 350 and 400 g kg?1 diet) and two lipid levels (100 and 140 g kg?1 diet) in a factorial manner (3 × 2) to provided six different dietary P:E ratio: 16, 17, 18, 19, 20 and 21 mg CP kJ?1 g?1). The result showed that the highest significant (P≤0.05) survival rate, growth indices and feed utilization were observed for M. rosenbergii PL fed a diet with a P:E ratio of 17 mg CP kJ?1 g1, whereas, the lowest value was recorded for prawns fed a diet with a P:E ratio of 20 mg CP kJ?1 g?1. Whole body contents of protein and lipid were highest (P≤0.05) when fed diets with 21 and 17 mg CP kJ?1 g?1 respectively. Concerning dietary protein levels, the highest (P≤0.05) values for survival and growth indices were observed for PL fed a diet containing 300 g kg?1 diet protein. The same trend was observed for PL fed a diet with 100 g kg?1 diet lipid level, irrespective of dietary protein levels. A diet containing 300 g kg?1 protein and 100 g kg?1 lipid with a dietary P:E ratio of 17 mg CP kJ g?1 is recommended to stimulate growth performance and nutrients utilization efficiency of M. rosenbergii PL.  相似文献   

12.
Ethoxyquin (EQ) is the most common synthetic antioxidant used for preventing rancidity in fish foodstuffs. However, literature related to the effects of dietary EQ on performance of fish was limited. The present study was conducted to investigate the effects of EQ on performance and EQ residue in muscle of juvenile Japanese seabass Lateolabrax japonicus and to estimate the optimal EQ concentration in the diet. Graded levels [0 (control), 50, 150, 450 and 1350 mg EQ kg?1 diet] of EQ were added to the basal diet, resulting in five dietary treatments in the experiment. Each diet was fed to triplicate groups of seabass (initial body weight 8.01 ± 0.76 g) for 12 weeks in floating sea cages (1.5 × 1.5 × 2.0 m, 30 fish per cage). Survival ranged from 78.9 to 86.7%, and was irrespective of dietary EQ levels. The specific growth rate (SGR) of fish fed diets supplemented with ≤50 mg kg?1 EQ had significantly (P < 0.05) higher SGR than fish fed diets supplemented with ≥150 mg kg?1 EQ, the highest SGR was observed in fish fed diet with 50 mg kg?1 EQ supplementation. Feed intake (FI) and feed efficiency (FE) were not significantly (P > 0.05) different among dietary treatments. Fish fed diets with 50 and 1350 mg kg?1 EQ had a significant (P < 0.05) lower body lipid content than fish in the control group. Muscle EQ level significantly increased when dietary EQ increased. Optimal EQ concentration estimated by polynomial regression based on maximum growth of juvenile Japanese seabass was 13.78 mg kg?1 diet.  相似文献   

13.
Young Arctic charr, Salvelinus alpinus (L.), mean weight 2.56 ± 0.02 g, were fed nine isoenergetic (?16.6 MJ digestible energy (DE) kg?1) practical diets formulated to supply digestible crude protein (DCP) at 40g kg?1 increments from 230 to 550g kg?1, for 84 days. Mean weight gain (MWG) and specific growth rate (SGR) were determined every 14 days while carcass composition was determined at the start and end of the experiment. Growth responses attained the highest values in the fish fed the diet with 350 g kg?1 DCP. Carcass moisture gain, protein gain and apparent net lipid accumulation increased as DCP levels increased to a maximum at 350 g kg?1 after which there were no differences among treatments. Total carcass lipid and lipid gain decreased as dietary DCP increased up to 470 g kg?1 with no differences thereafter. Apparent net protein accretion decreased with increasing DCP levels up to 350 g kg?1 after which there were few differences among treaments. Protein requirements were estimated by fitting MWG and SGR data to broken line regression, quadratic and saturation kinetics models. Results from these analyses suggest that dietary DCP should be provided at between 340 and 392 g kg?1 (equivalent to ?370 and 420g kg?1 crude protein) for optimal growth of young Arctic charr reared in similar conditions.  相似文献   

14.
Two experiments were conducted to quantify the dietary thiamin (experiment I) and pyridoxine (experiment II) requirements of fingerling Cirrhinus mrigala for 16 weeks. In experiment I, dietary thiamin requirement was determined by feeding seven casein–gelatin‐based diets (400 g kg?1 CP; 18.69 kJ g?1 GE) with graded levels of thiamin (0, 0.5, 1, 2, 4, 8 and 16 mg kg?1 diet) to triplicate groups of fish (6.15 ± 0.37 cm; 1.89 ± 0.12 g). Fish fed diet with 2 mg kg?1 thiamin had highest specific growth rate (SGR), protein retention (PR), RNA/DNA ratio, haemoglobin (Hb), haematocrit (Hct), RBCs and best feed conversion ratio (FCR). However, highest liver thiamin concentration was recorded in fish fed 4 mg thiamin kg?1 diet. Broken‐line analysis of SGR, PR and liver thiamin concentrations exhibited the thiamin requirement in the range of 1.79–3.34 mg kg?1 diet (0.096–0.179 μg thiamin kJ?1 gross energy). In experiment II, six casein–gelatin‐based diets (400 g kg?1 CP; 18.69 kJ g?1 GE) containing graded levels of pyridoxine (0, 2, 4, 6, 8 and 10 mg kg?1 diet) were fed to triplicate groups of fish (6.35 ± 0.37 cm; 1.97 ± 0.12 g). Fish fed diet containing 6 mg kg?1 pyridoxine showed best SGR, FCR, PR, RNA/DNA ratio, Hb, Hct and RBCs, whereas maximum liver pyridoxine concentration was recorded in fish fed 8 mg kg?1 dietary pyridoxine. Broken‐line analysis of SGR, PR and liver pyridoxine concentrations reflected the pyridoxine requirement from 5.63 to 8.61 mg kg?1 diet. Data generated during this study would be useful in formulating thiamin‐ and pyridoxine‐balanced feeds for the intensive culture of this fish.  相似文献   

15.
A 70‐day feeding experiment was conducted to assess the dietary vitamin A (VA) requirements of juvenile Japanese flounder (Paralichthys olivaceus). Six semi‐purified diets with VA supplementations of 0, 5000, 10 000, 15 000, 20 000 and 25 000 IU kg?1 were fed twice a day to triplicate groups of 20 juveniles per tank with an initial weight of 1.59 ± 0.01 g (mean ± SE). Weight gain (WG) and specific growth rate (SGR) increased as dietary VA increased up to 10 000 IU kg?1. Significantly lower WG and SGR were observed for the 0 IU kg?1 treatment than for treatments of 5000, 10 000 and 15 000 IU kg?1. Highest WG and SGR were observed in fish fed 10 000 IU kg?1; slightly lower values were recorded in fish fed 15 000, 20 000 or 25 000 IU kg1. No significant difference was observed in survival rate among treatments. Whole body total lipid was significantly higher in fish fed 0 and 5000 IU kg?1 than for other levels. Reduced growth and small livers were observed as signs of VA deficiency in fish fed 0 IU kg?1. Slightly reduced growth and pale fragile livers were observed as effects of VA excess in fish fed 25 000 IU kg?1. Total retinol contents in liver and eyes increased with increasing levels of dietary VA. No retinol was detected in livers, and significantly lower total retinol content was observed in eyes, of fish fed 0 IU kg?1. WG analysed by the broken line method indicated that an optimum dietary VA requirement of 9000 IU kg?1.  相似文献   

16.
The number of 360 individuals with an average initial weight of 87.8 ± 0.04 g was fed six diets containing graded levels of choline at 8.1 (control group), 602.5, 1119.0, 1511.5, 1970.0 and 4029.0 mg choline kg?1 diet, respectively, to investigate the effects of dietary choline on growth performance, lipid deposition and hepatic lipid transport for grouper, Epinephelus coioides. Dietary methionine was estimated to be 10.02 g kg?1, less than the requirement (13.10 g kg?1). The results of 10‐week study period indicated that the best values of specific growth rate (SGR), feed conversion rate (FCR) and protein efficiency rate (PER) all occurred in 1119.0 mg choline kg?1 diet (P < 0.05). The survival range increased from 8.1 to 1511.5 mg choline kg?1 diet and then plateaued. Dietary choline supplementation significantly decreased the liver lipid content of grouper (P < 0.05), but the lipid content of the muscle tended to be increased firstly and then decreased (P < 0.05). Liver choline concentration reached a plateau in 1511.5 mg choline kg?1 diet and then levelled off (P < 0.05). Serum high density lipoprotein‐cholesterol (HDL‐C) and total cholesterol (TCHO) levels were firstly decreased and then increased with dietary choline supplementation. A reversed tendency, however, was found in triglyceride. Broken‐line regression analysis of SGR and liver choline content indicated that choline requirement of grouper was 1093.7 and 1579.7 mg kg?1 diet, respectively.  相似文献   

17.
Nine isoenergetic (18.5 kJ g?1) diets were formulated in a 3 × 3 factorial design to contain three protein levels (350, 400 and 450 g kg?1) for each of three lipid levels (65, 90 and 115 g kg?1), respectively, and fed twice daily for 8 weeks to fish of mean initial weight 3.34 ± 0.02 g reared in a re‐circulatory water system. Temperature, pH and dissolved oxygen (DO) were maintained within the range 28–30 °C, 5.6–6.8 and 4.82–6.65 mg L?1 respectively throughout. Results show that fish survival was better in the groups fed 65 g kg?1 lipid while growth performance (% weight gain, WG; specific growth rate, SGR) and nutrient utilization (feed conversion ratio, FCR; protein efficiency ratio, PER; protein intake, PI) in the 65/450 and 90/450 g kg?1 treatments were similar and significantly (P < 0.05) higher than in fish fed the other lipid/protein ratio combinations. The body indices monitored (Hepatosomatic index, HSI and viscerosomatic index, VSI) were similar among the treatments whereas intestinal lipase activity was not significantly (P < 0.05) affected by increase in dietary lipid and protein levels. Carcass composition showed that dietary protein level affected body protein content positively in the 65 and 90 g kg?1 lipid treatments, but dietary lipid level did not affect body lipid content. A lipid/protein ratio of 65/450 g kg?1 is considered adequate for good growth performance and survival of Channa striatus fry.  相似文献   

18.
Two feeding trials of 8 and 10 weeks each were conducted to quantify the dietary lysine requirement of juvenile striped bass, Morone saxatilis. Diets in both experiments contained approximately 420 g crude protein kg–1 and 13.4 MJ digestible energy (DE) kg?1. L ‐Lysine‐HCl was added to the basal diet to yield five and six treatments in the two experiments. Diets in the first experiment were determined to contain 9.2, 14.1, 14.6, 19.9 and 21.0 g available lysine kg?1 on a dry‐matter basis. Diets in the second experiment were determined to contain 14.8, 18.1, 21.3, 24.5, 27.6 and 30.9 g available lysine kg?1 on a dry‐matter basis. Weight gain, specific growth rate (SGR), feed conversion ratio (FCR), and apparent nitrogen utilization (ANU) were significantly (P < 0.05) improved by increasing dietary lysine concentrations to approximately 20 g kg?1 of diet. Least‐squares regression analysis of weight gain and SGR in the first experiment indicated a minimum dietary lysine requirement of 20.1 ± 2 g kg?1 dry diet. Least‐squares regression analysis of the same criteria measured in the second experiment yielded the following estimates of dietary lysine requirements (g kg?1 dry diet): 19.8 ± 2.3 for weight gain, 21.7 ± 1.5 for SGR, 23.7 ± 3.5 for FCR and 18.6 ± 1.3 for ANU. From these results the minimum recommended dietary lysine requirement for optimal growth of juvenile striped bass is approximately 21 g kg?1 dry diet which equates to 49 g kg?1 dietary protein or 1.57 mg kJ?1 DE. Although higher than that reported for hybrid striped bass, this requirement level is similar to those reported for many other fish species.  相似文献   

19.
A growth trial was conducted to examine the effect of dietary digestible energy (DE) content on methionine (Met) utilization and requirement in juvenile Nile tilapia (Oreochromis niloticus). Ten iso‐nitrogenous (288 g kg?1 protein) practical diets, with two DE levels (10.9 MJ kg?1; 12.4 MJ kg?1) and five methionine supplementation levels (0, 1, 2, 4 and 6 g kg?1), were hand‐fed twice daily to triplicate groups of Nile tilapia (initial body weight 8.95 ± 0.06 g) for 8 weeks. Weight gain (WG) and specific growth rate (SGR) increased significantly with increasing dietary methionine concentration at the same DE content (P < 0.001). At the same dietary methionine level, WG and SGR of fish fed high‐DE diets were significantly higher than that of fish fed low‐DE diets (P = 0.0001), although no interaction was found between dietary DE and methionine supplementation. Based on quadratic regression analysis between dietary methionine concentration and weight gain, optimal methionine requirement for maximum growth, expressed as g Met required kg?1 diet (low‐ versus high‐DE diets), increased as diet DE concentration increased (7.34 versus 9.90 g kg?1 diet, respectively; with cysteine 4.70 g kg?1 diet). The results indicated that diet DE content affects methionine utilization and requirement in juvenile Nile tilapia, fish fed high‐DE diets required more methionine for maximum growth.  相似文献   

20.
A study was conducted to estimate the optimum requirement of dietary available phosphorus for GIFT strain of Nile tilapia Oreochromis niloticus. Six purified diets were formulated to contain graded levels (0 (control diet), 2.9, 4.8, 7.6, 9.1 and 10.9 g kg?1 diet) of available phosphorus. Each diet was fed to triplicate groups of 12 fish with initial average weight (46.03 ± 2.14) g for 8 weeks. The results showed that fish fed the three lowest phosphorus diets (0, 2.9 and 4.8 g kg?1) had significantly lower weight gain rate, specific growth rate (SGR) and feed efficiency than those fed the other diets (P < 0.05). The survival rate of fish fed the control diet was significantly lower than that of the fish fed the other diets (P < 0.05). Whole body viscerosomatic index and crude lipid content decreased significantly with increasing dietary available phosphorus levels (P < 0.05), while the contents of crude ash, calcium, phosphorus in the whole body and vertebrae showed the opposite trend (P < 0.05). The blood chemistry analysis showed that dietary available phosphorus had significant effects on serum phosphorus concentration, enzyme activities of alkaline phosphatase and parathyroid hormone level. Quadratic curve analysis based on SGR indicated that the minimum dietary requirement of available phosphorus for maintaining optimal growth of tilapia was 8.6 g kg?1.  相似文献   

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