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1.
The effect of a gradual substitution of dietary fish meal protein by soya meal protein on growth, feed uptake and protein utilization of 1 g Colossoma macropomum (Cuvier) was studied at two different dietary protein levels. Growth rates of fish fed ad libitum 20 and 45% protein diets fluctuated between 41 and 49, and between 60 and 68 g kg-0 8 day-1, respectively. Fish incorporated between 31 and 47% of the dietary protein in their body. Increased amounts of soya meal in the diet led to decreased feed uptake, higher body protein levels, lower ash levels and increased NPU values. If the low ash contents in the fish fed 100% soya diets are not prejudicial for health and growth of the fish in the long term, soya meal must be considered a superior protein source for C. macropomum. The high growth and the efficient use of the dietary protein indicate the C. macropomum is able to utilize soya protein more efficiently than other fish species.  相似文献   

2.
Juvenile Colossoma macropomum were fed ad libitum diets containing either 30% or 40% protein, while the dietary lipid level varied between 5% and 20%. Growth and protein utilization efficiency increased with the dietary lipid level. However, the economic feasibility of the addition of extra dietary lipid to C. macropomum diets is questionable, as for every extra gram of protein deposition it was necessary to replace 20–25 g of dietary carbohydrates by lipids. Moreover, increased dietary lipid levels resulted in increased lipid deposition. In C. macropomum, feed uptake was regulated by the dietary protein level and unaffected by the dietary lipid level. Dissection of the body into head, viscera and trunk revealed that 45–48% of the body lipids were stored in the trunk, independent of diet composition. A positive relation between dietary and body protein level was confirmed in this experiment. However, the dissection of the body revealed that the body protein concentrations in head + viscera and trunk are not changed significantly by the dietary protein level. The higher protein contents offish fed higher-protein diets are due to an increase in the relative weight of the trunk (muscle) to the total body weight.  相似文献   

3.
A feeding trial was conducted to study the effect of six iso‐energetic diets containing 25, 30, 35, 40, 45 and 50% crude protein (CP) on growth, survival and feed conversion ratio (FCR) as well as the protein requirement of an endangered cyprinid, Tor putitora. Triplicate groups of fingerlings with initial total length of 10.0–11.0 cm and weight of 12.0–12.5 g were reared in earthen ponds and fed diets at 5% of body weight for 120 days. Performance was evaluated on the basis of total length gain, body weight gain, survival rate, feed efficiency, FCR, protein efficiency ratio, specific growth rate, energy retention, gross and net yield in kg ha?1. Whole‐body carcass composition of fish was analysed at the start and the end of the experiment. Growth and FCR were influenced significantly (P<0.05) by dietary CP contents; higher growth and lower FCRs were obtained with increasing dietary protein. Dietary protein also influenced the whole‐body carcass composition of the fish. Higher protein and ash, and lower moisture and lipid in the whole body were observed with increasing dietary protein. Broken‐line regression analysis indicated that the optimum dietary protein level for maximal growth of mahseer lies between 45% and 50% (45.3%). Overall feed utilization and growth performance of the fish is comparable to that of other aquaculture species and the fish offers high potential for commercial aquaculture.  相似文献   

4.
This study was conducted to determine the effect of dietary CLA (Conjugated linoleic acid) levels on growth performance, fatty acid profiles and lipid metabolism of liver in Synechogobius hasta. Fish were fed six diets with fish oil replaced by 0 (control), 5, 10, 15, 20 and 25 g kg?1 CLA for 8 weeks. Weight gain, WG, and SGR (specific growth rate) tended to increase when dietary CLA levels increased from 0 to 10 g kg?1 and then decline with further increasing dietary CLA levels to 25 g kg?1. FCR (feed conversion ratio) showed contrary trend with WG and SGR. The reduced VSI (vicero somatic index) and increased HSI (hepatosomatic index) were observed in fish fed increasing dietary CLA levels. Whole‐body lipid content declined, but hepatic lipid content increased with increasing dietary CLA levels. Dietary CLA modified total percentages of the main groups of fatty acids in liver. Hepatic 6PGD, ME and ICDH activities increased with increasing dietary CLA levels. FAS and G6PD were very variable and not related to dietary treatments. CPT I activities showed no significant differences among the treatments. Based on second‐order polynomial regression analysis of WG and FCR against dietary CLA level, 8.7–10.1 g kg?1 was indicated to be the optimal dietary CLA range for maximum growth and feed utilization for S. hasta.  相似文献   

5.
Three size groups of Colossoma macropomum were submitted to a 4-week growth trial. Five nearly isocaloric (18.8-21.0 kJ g?1) diets with protein concentrations ranging between 17 and 64% were administrated at a fixed, near satiation level. Maximum growth was 6.6, 3.6 and 1.9 g protein kg?0.8 day?1 for 5, 50 and 125 g fish, respectively. The protein requirement to achieve maximum growth decreased from 28.9 g protein kg?0.8 day?1 for 5 g fish to 11.7 g kg?0.8 day?1 for 125 g fish. Possibly because of its high growth rate. C. macropomum needs a slightly higher dietary P/E ration (25.4-27.9 mg protein kJ?1) to obtain maximal growth than most other fishes. The relation between protein ration and protein gain was studied by a quadratic regression model. In fish receiving protein rations equal or below rations resulting in maximal growth, protein ration and protein gain were almost linearly related. The model showed that the portion of the dietary protein which is digested decreases with increasing protein ration. Body protein content increased and body lipid content decreased with feed protein level. Fish fed a 17% protein diet deposited as much as 18% lipid.  相似文献   

6.
The present study was designed to determine the optimal dietary lysine requirement for jundiá, Rhamdia quelen, fingerlings. Groups of 17 fish (1.4 ± 0.1 g) were stocked in 120‐L tanks and were fed semipurified diets (33% crude protein [CP] and 3500 kcal metabolizable energy) containing increasing concentrations of lysine (3.0, 4.0, 4.5, 5.0, 5.5, 6.0, and 6.5% CP). After 119 d, fish weight gain (WG), specific growth rate (SGR), feed intake and feed conversion (FC), apparent net protein utilization (ANPU), body composition (CP, fat, and ash), and vertebral collagen were determined. WG and SGR increased as dietary lysine concentration in protein increased up to 4.5%, reducing at 6.0 and 6.5% lysine. Fish that were fed the lowest lysine concentration presented the worst feed conversion (FC), which improved for fish fed with 4.5% or more lysine. Feed consumption followed the same trend as FC. The highest ANPU was observed in fish fed with 4.5% lysine. Fish fed diets containing 4.5, 5.0, and 5.5% lysine accumulated more body protein (P < 0.05). Collagen vertebral concentration was significantly higher in fish fed with the 4.5% lysine diet. Dietary requirement for lysine was 4.5 or 5.1% depending on the statistical model used for estimation: broken line or polynomial regression, respectively. The requirements for the other essential amino acids were estimated on the basis of the ideal protein concept and were similar to the requirements for other fish species, except for isoleucine, leucine, treonine, and valine, which were higher for jundiá.  相似文献   

7.
A growth trial was conducted to estimate the optimum concentration of dietary calcium (Ca) for grass carp (Ctenopharyngodon idella). Triplicate groups of grass carp (4.52 ± 0.02 g) were fed diets containing graded levels (2.75, 4.51, 6.24, 7.99, 9.66 and 11.5 g kg?1) of Ca for 8 weeks. Weight gain, feed efficiency and protein efficiency ratio were linearly increased up to the 7.99 g kg?1 dietary Ca and then maintained stable beyond this level (P < 0.05). Dietary Ca levels higher than 7.99 g kg?1 significantly increased the ash contents of whole body, vertebrae and scales. Ca contents in whole body, vertebrae and scales were linearly increased up to the 7.99 g kg?1 dietary Ca and then maintained stable beyond this level (P < 0.05). In contrast, dietary Ca levels higher than 9.66 g kg?1 significantly decreased Mg contents in whole body, vertebrae and scales. Dietary Ca levels higher than 7.99 g kg?1 significantly increased plasma alkaline phosphatase activity. However, plasma Ca, P and Mg contents were not significantly affected by dietary Ca supplements (P > 0.05). Polynomial regression analysis indicated that 10.4 g kg?1 dietary Ca was required for maximal tissue storage and mineralization as well as optimal growth.  相似文献   

8.
Dietary phosphorus requirement of fingerling Labeo rohita (6.1 ± 0.13 cm; 1.88 ± 0.05 g) was quantified by feeding seven isonitrogenous (350 g/kg crude protein) and isocaloric (16.72 kJ/g gross energy) purified diets with different levels of phosphorus as 3.5 (basal diet), 4.6, 5.7, 6.5, 7.8, 8.9, and 10.1 g/kg. Triplicate groups of fish were fed at 0800, 1200, and 1600 h to apparent satiation for 8 wk. Live weight gain (LWG; 494.68%), specific growth rate (3.18%/d), feed conversion ratio (1.54), feed efficiency (0.65), protein gain (PG; 1.26 g/fish), protein efficiency ratio (1.86), and phosphorus utilization efficiency (98.78%) improved significantly (P < 0.05), with increasing dietary phosphorus level up to 6.5 g/kg. However, phosphorus contents of vertebrae and scale increased significantly up to 7.8 g/kg. Dietary phosphorus levels significantly affected serum phosphorus concentration and alkaline phosphatase activity. Broken‐line analysis based on LWG; PG; and whole‐body, vertebrae, and scale phosphorus against dietary phosphorus indicated the optimal phosphorus requirement of fingerling L. rohita at 6.56, 6.58, 6.56, 8.02, and 8.44 g/kg diet, respectively. In order to restrict superfluous phosphorus in the diet, inclusion of 6.56 g/kg phosphorus is recommended for optimal growth of fingerling L. rohita.  相似文献   

9.
Black soldier fly meal (BM) is an outstanding candidate as a fish meal (FM) substitute because it contains relatively high protein and essential amino acids. In this study, we replaced FM in red sea bream diets (Pagrus major) with BM to investigate its effect on growth and feed utilization. Six isonitrogenous and isolipidic experimental diets were prepared by substituting 0%, 20%, 40%, 60%, 80% and 100% FM protein with BM (Control, BM20, BM40, BM60, BM80 and BM100, respectively). After the 8-week feeding trial, final body weight, weight gain, specific growth rate and feed efficiency decreased linearly with increasing dietary BM level (p < 0.05). Apparent digestibility of protein and fat and serum total cholesterol concentration decreased with increasing dietary BM levels (p < 0.05) Final body weight, WG, SGR and FE against dietary BM level had breaking points of 76.2%, 41.7%, 76.5% and 60.0%, respectively, in segmental regression analysis. In conclusion, the results suggest that BM can replace a maximum of 41.7% of FM in the diet of red sea bream without compromising growth performance or feed efficiency for 56 days.  相似文献   

10.
This study evaluated the effect of dietary thiamin on growth performance, feed utilization and non‐specific immune response for juvenile Pacific white shrimp, Litopenaeus vannamei. Six isonitrogenous and isolipidic practical diets were formulated with graded thiamin levels of 6.9, 32.7, 54.2, 78.1, 145.1 and 301.5 mg kg?1 of dry diet, respectively. Each diet was randomly assigned to triplicate groups of 30 juvenile shrimp and provided four times each day to apparent satiation. Weight gain (WG) and specific growth rate (SGR) of the shrimp were significantly influenced by the dietary thiamin levels, the maximal WG and SGR occurred at 54.2 mg kg?1 dietary thiamin level. However, with further increase in dietary thiamin level from 54.2 to 301.5 mg kg?1, the WG and SGR significantly decreased. Shrimp fed the 54.2 mg kg?1 thiamin diet exhibited higher feed efficiency, protein efficiency ratio and protein productive value than those fed the other diets. Dry matter and protein content in whole body were significantly affected by the dietary thiamin levels. Thiamin concentration in hepatopancreas significantly increased when the dietary thiamin level increased from 6.9 to 145.1 mg kg?1. The total protein, glucose, triacylglycerol and cholesterol contents in hemolymph were not significantly affected by the dietary thiamin levels. Dietary thiamin had significantly influenced superoxide dismutase, catalase and lysozyme activities in hemolymph. Results of this study indicated that the optimal dietary thiamin requirements estimated using a two‐slope broken‐line model based on WG and thiamin concentration in hepatopancreas were 44.66 and 152.83 mg kg?1, respectively.  相似文献   

11.
Effects of dietary phytase, amino acid (AA), and inorganic phosphorus (P) in soybean meal (SBM) diets on the growth, feed utilization, and P waste of Australian catfish, Tandanus tandanus, were evaluated. In Experiment 1, SBM replaced 30% of fishmeal (FM) protein in the four test diets, supplemented with phytase (1000–3000 FTU/kg). In Experiment 2, SBM replaced 45% of FM protein in the four test diets, supplemented with phytase, AAs, inorganic P, or their combinations. Inclusion of 3000 FTU/kg significantly improved growth performance and feed utilization of catfish. Ortho‐P waste was significantly lower in fish fed with SBM diets. At 30% FM protein replacement, dietary SBM did not reduce the total P waste of catfish while dietary phytase significantly did. At 45% FM protein replacement, phytase alone did not significantly improve the growth and feed utilization of catfish fed with SBM diets while significantly better results were obtained when both phytase and AAs were supplemented. Dietary inclusion of inorganic P significantly decreased P utilization and increased P waste of the fish. Dietary phytase significantly improved P utilization of catfish in both experiments.  相似文献   

12.
An 83‐day feeding trial was carried out to determine the effect of different dietary protein and lipid levels on the growth performances and carcass composition of white seabream. Juveniles (10.7±0.2 g) were fed to satiation on four diets, varying in protein (15% and 28%) and lipid (12% and 16%) levels. The best growth performance was observed in fish fed on diets with higher protein level. Dietary lipids did not affect growth performance. Voluntary feed intake decreased with a increasing dietary protein level at both dietary lipid levels. Feed conversion ratio improved with the increase in dietary protein and lipid levels. Carcass composition remained unaltered by dietary protein levels (P>0.05). Carcass protein content tended to decrease, while lipid content tended to increase in groups fed on 16% lipid, compared with the 12% lipid groups. Additionally, protein retention was higher in fish fed on low‐protein and low‐lipid levels, compared with the high‐protein and high‐lipid group (29% vs. 19%). Lipid retention increased significantly with dietary protein level (P<0.001). Energy retention improved with dietary protein, but was not affected by dietary lipid levels. On the basis of our results, feeding white seabream on 15% dietary protein had a negative effect on growth and feed utilization. Dietary lipid did not induce a protein‐sparing action in Diplodus sargus juveniles.  相似文献   

13.
This study was conducted to investigate the effects of varying carbohydrate (CHO) fractions on growth, body composition, metabolic, and hormonal indices in juvenile black carp, Mylopharyngodon piceus. Juvenile black carp, M. piceus (average weight: 1.5 ± 0.05 g) were fed with graded levels of dietary available CHO (0.06, 10.65, 19.43, 28.84, 37.91, and 47.38%) for 9 wk, respectively. Results showed that the highest weight gain could be obtained at 24.98% dietary CHO using second‐order polynomial regression model; and optimal dietary available CHO content (28.84%) could significantly increase the final body weight and the protein efficiency ratio (PER) while reducing the feed conversion ratio (FCR) (P < 0.05). Dietary available CHO could gradually increase the hepatosomatic index, the crude lipid contents in the whole body and the glucose and triglyceride content in the plasma. The activities of glycolysis enzymes and glucose‐6‐phosphate dehydrogenase could be increased with increasing dietary available CHO. The activities of glucose‐6‐phosphatase and fructose‐1,6‐bisphosphatase were firstly decreased at 10.65% dietary available CHO and increased to stable level at 19.43% dietary available CHO. In addition, both 19.43 and 28.84% dietary available CHO could increase the adiponectin contents in the plasma of black carp, M. piceus. Meanwhile, both 19.43 and 28.84% dietary available CHO could significantly increase the mRNA expression levels of growth hormone, insulin, ghrelin, neuropeptide Y, somatostatin I, and somatostatin II in juvenile black carp, M. piceus, compared with the CHO‐deficient diet (0.06%). These results suggest that optimal inclusion of dietary CHO fractions (19.43–28.84%) could improve metabolic homeostasis and promote growth and feed efficiency in juvenile black carp, M. piceus.  相似文献   

14.
Abstract

A 3 × 3 factorial experiment was designed to determine the effects of protein levels and feeding rate on growth and body composition of hybrid clariid catfish, Clarias gariepinusX Heterobranchus bidorsalis, over 12 weeks experimental period. Hybrid catfish (initial mean weight 12.53±0.35 g) were stocked in three feeding rates (3%, 5%, or 7% body weight/day (bw/day) and three crude protein levels (30%, 35%, or 40%). Each treatment was assigned randomly to three tanks. Final weight was higher for fish fed at 40% than those fed at 30% and 35% CP. There was no significant difference (P >0.05) in fish fed at 3%, 5%, and 7% bw/day. Also, there was no significant interaction between feeding rate and dietary protein level for weight gain, specific growth rate or feed conversion ratio. Weight gain and feed efficiency under feeding rates increased linearly as protein level increased. Dietary protein levels and feeding rate had significant effect on fish survival. Protein levels had a positive linear effect on fish body protein in all the feeding rates. Based on the above results, 40% CP level and 5% bw/day feeding rate are suggested to be optimal for achieving optimum growth rate and body composition.  相似文献   

15.
Juvenile, 1-g Colossoma macropomum (Cuvier) were fed two different diets: one with fish meal and another with soya meal as the main dietary protein source. Both diets were provided at ad libitum feeding level, and at two restricted feeding levels of ～ 80% and 60% of the ad libitum level. The experiment was performed in 30 aquaria, each stocked with 12 fish. For each treatment (two diets X three feeding levels), there were five replicates. Fish were fed three times daily at 0900, 1300 and 1700 h. At sampling days (days 14, 29, 44) in each aquarium in one of these feedings, chromic-oxide-marked feed was used. Shortly after the last meal, fish were weighed and four fish were taken from each aquarium for determination of the chromic oxide content in their digestive tract. Fish fed the fish meal diet attained a higher weight but had a lower body protein content. At the ad libitum feeding level, feed intake of the fish meal diet was higher, but feed and protein utilization efficiency were lower than with the soya diet. However, statistical analysis of the data of both the ad libitum and the two restricted feeding levels revealed that the reduced voluntary feed intake of the soya diet was the cause of its better utilization with ad libitum feeding. There is no evidence that soya protein is more freely available than fish meal protein. The chromic oxide data showed that 15 min after feeding, all of the feed (99.8%) could be traced back in fish fed the lowest feeding level, while at the ad libitum feeding level the recovery was only 72%. These data confirmed the hypothesis that at high feeding levels, considerable amounts of feed remain uneaten. Feed losses were not significantly different between the two diets. The chromic oxide recovery data of the 0900 h and 1300 h feedings showed that the feed passage rate in the digestive tract was similar for the three different feeding levels. Due to the high feed losses at high feeding levels, the relation between feed ration and feed utilization is determined mainly by the percentage of feed losses at the different feed rations.  相似文献   

16.
A growth trial was conducted to estimate the optimum concentration of dietary magnesium (Mg) for grass carp (Ctenopharyngodon idella). Triplicate groups of grass carp (5.56 ± 0.02 g) were fed diets containing graded levels (187, 331, 473, 637, 779 and 937 mg kg?1) of Mg for 8 weeks. Weight gain, specific growth rate and feed efficiency were linearly increased up to 637 mg kg?1 dietary Mg and then levelled off beyond this level. For body composition, dietary Mg levels higher than 473 mg kg?1 significantly decreased the moisture content but increased the lipid content of whole body, muscle and liver. Dietary Mg levels higher than 473 mg kg?1 significantly decreased the ash contents of vertebrae, scales and muscle. Mg contents in whole body, vertebrae, scales and plasma were increased up to 637 mg kg?1 dietary Mg and then levelled off beyond this level. However, Ca and P contents seem to be inversely related to dietary Mg. Dietary Mg levels higher than 473 mg kg?1 significantly decreased Zn and Fe contents in whole body and vertebrae. Broken‐line analysis indicated that 687 mg kg?1 dietary Mg was required for maximal tissue Mg storage, as well as satisfied for the optimal growth.  相似文献   

17.
A growth experiment was conducted to determine the optimal dietary protein requirement for juvenile ivory shell reared in indoor aerated aquaria. Six isoenergetic experimental diets using fish meal, casein and gelatin as protein sources were formulated to contain graded levels of protein (27, 33, 38, 43, 49 and 54% of dry diet, respectively). Triplicate groups of 40 shells (average weight 93.50 ± 1.70 mg) were stocked in 120-l tanks and fed to apparent satiation twice daily for 8 weeks. The results showed that the growth performance and feed utilization were significantly affected by dietary protein level (P < 0.05). Maximum weight gain, mean protein gain, specific growth rate and soft body to shell ratio occurred at 43% dietary protein level (P < 0.05). There were significant differences in protein, lipid, moisture and ash content in soft body; except that ash content in shell was not significantly affected by dietary protein level. Pepsin activity in soft body tissue significantly increased with dietary protein level up to 43%, and trypsin-like enzyme activity increased with dietary protein level up to 49%. However, lipase activity in soft body decreased with increasing dietary protein level. However, no significant differences (P < 0.05) in survival, calcium, phosphorus concentration in the shell and soft body were found among dietary treatments. Quadratic regression analysis of weight gain against dietary protein level indicated that the optimal dietary protein requirement for maximum growth and feed utilization of juvenile ivory shell is 45% of dry diet.  相似文献   

18.
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   

19.
An 8‐week feeding trial was conducted to investigate the effects of dietary carbohydrate to lipid ratio (CHO: L) on growth, feed utilization, body composition and digestive enzyme activities of golden pompano, Trachinotus ovatus. Five iso‐nitrogenous (450 g/kg protein) and iso‐energetic (19 MJ/kg gross energy) diets with varying CHO: L ratios of 0.68, 1.02, 1.62, 2.61 and 4.35, respectively, were fed to triplicate groups of 30 fish (average 13.8 ± 0.1 g). Results showed that dietary CHO: L ratios did not show any significant influence on survival of golden pompano (p > .05) but significantly affected its growth performance and feed utilization (p < .05). Fish fed diets with CHO: L ratios at 1.62 and 2.61 exhibited the highest final body weight, weight gain ratio, specific growth rate, feed efficiency ratio and protein efficiency ratio. Fish body lipid and liver glycogen contents were also significantly influenced by CHO: L ratio (p < .05). Hepatic amylase activity increased firstly and then decreased as the dietary CHO: L ratio increased, while lipases activity decreased with increasing dietary CHO:L level. The regression model analysis showed that the most suitable dietary CHO: L ratio (protein 450 g/kg) to reach the highest weight gain ratio is 2.38.  相似文献   

20.
Juvenile, 0.87 g Colossoma macropomum (Cuvier) were submitted to different ad libitum feeding regimes. Feeding frequency ranged from one to five meals per day and intervals between meals from 3 h to 24 h. Higher feeding frequencies resulted in higher feed uptake, a higher growth rate and a decreased feed utilization efficiency. Feed consumption was lower at 0700 h than at 1900 h. The amount of feed from different meals persisting in the digestive tract was determined with chromic-oxide-marked feed. This method revealed that with ad libitum feeding, about 21% of the feed remained uneaten. Feed losses did not differ significantly between feeding regimes. Feed accumulated in the digestive tract in the morning and early afternoon. In the late afternoon most feed rests disappeared from the digestive tract and feed consumption increased. It is suggested that feed uptake and growth of C. macropomum can be improved by extending the feeding period after 1900 h.  相似文献   

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