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1.
Two 8‐week growth trials were conducted in indoor recirculation system to evaluate the protein requirements for juvenile (3.70 ± 0.20 g) and pre‐adult (85.2 ± 0.70 g) gibel carp, Carassius auratus gibelio var. CAS III. Six isoenergetic diets were formulated for each trial using fish meal and casein as protein sources, and protein level was 250–450 g kg?1 in Trial 1 and 200–450 g kg?1 in Trial 2. With the increasing dietary protein, feeding rate (FR) and feed conversion ratio (FCR) significantly decreased (P < 0.05). Weight gain (WG) increased first and then reached a plateau in 330–450 g kg?1 in Trial 1 (P > 0.05), while decreased after the maximum value in 350 g kg?1 in Trial 2 (P < 0.05). Productive protein values (PPVs) were lower in 370–450 g kg?1 in Trial 1 and 400–450 g kg?1 in Trial 2 (P < 0.05). Increasing dietary protein level increased protein content and decreased lipid content in whole fish body and white muscle (P < 0.05). Apparent digestibility coefficient of dry matters (ADCd) decreased, while apparent digestibility coefficient of protein (ADCp) increased in 370–450 g kg?1 in Trial 1 and 250–450 g kg?1 in Trial 2 (P < 0.05). Trypsin activity significantly increased in 370–450 g kg?1 in Trial 1 (P < 0.05) and was not affected in Trial 2 (P > 0.05). Hepatic alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities in both trials increased when dietary protein was above 400 g kg?1 (P < 0.05). Based on quadratic regression of WG, it was estimated that dietary protein requirement for maximum growth was 414 g kg?1 (digestible protein of 376 g kg?1) and 365 g kg?1 (digestible protein of 324 g kg?1) for juvenile (3.70 g) and pre‐adult gibel carp (85.2 g).  相似文献   

2.
Two 8‐week feeding trials were conducted to evaluate dietary carbohydrate utilization by omnivorous gibel carp (Carassius auratus gibelio) (2.4 ± 0.1 g) and herbivorous grass carp (Ctenopharyngodon idellus) (6.5 ± 0.1 g). Five isonitrogenous (370 g kg?1) and isolipid (70 g kg?1) diets were formulated with increasing corn starch levels (60, 140, 220, 300 and 380 g kg?1). Results showed that specific growth rate (SGR), feed efficiency (FE) and protein retention efficiency (PRE) of gibel carp significantly increased from dietary starch of 60 to 300 g kg?1 and then decreased from 300 to 380 g kg?1, but those of grass carp showed no significant differences between treatments. Independent of dietary starch levels, grass carp gained significantly higher FE and PRE than gibel carp. Feeding rate (FR) of gibel carp was significantly higher than that of grass carp. In two fish species, high dietary starch (300 and 380 g kg?1) tended to obtain higher hepatosomatic index (HSI), serum triglyceride, hepatic lipid and body lipid contents. Serum glucose concentration of grass carp was not affected, while that of gibel carp fed the starch of 300 g kg?1 diet was significantly lower than those of the fish fed other four diets (60, 140, 220 and 380 g kg?1). Grass carp showed high tolerance to dietary starch while dietary corn starch should be no more than 300 g kg?1 for gibel carp. High starch contents may cause lipid accumulation in the liver and body.  相似文献   

3.
A ten‐week feeding trail was conducted to investigate the effects of increasing DL‐methionine (Met) supplementation on the success of fish meal (FM) replacement with plant proteins in practical diets for juvenile gibel carp, Carassius auratus gibelio. Twelve isoenergetic diets were formulated including two 150 g kg?1 FM diets (Diet 1—positive control 1 reflecting a commercial diet and Diet 2—positive control 2 reflecting a commercial diet but with balanced essential amino acid (EAA) profile) and ten 50 g kg?1 FM diets (negative controls) supplemented with graded levels (0–3.0 g kg?1) of DL‐Met (Diets 3–12). Each diet was fed to triplicate groups of gibel carp, near satiation four times daily for 10 weeks. Diet 2 with balanced EAA profile produced better final weight, specific growth rate (SGR) and feed conversion ratio (FCR) than the negative control diet containing no supplemental Met (Diet 3), but did not significantly differ from Diet 1. However, DL‐Met supplementation (0.5–3.0 g kg?1) in the negative control diets (Diets 4–12) produced growth performances similar to those fed the positive control diets (Diets 1 and 2). Based on quadratic regression analysis, the optimal dietary Met level with 5.2 g kg?1 of dietary cysteine (Cys) was found to be 7.1 g kg?1 dry diet for SGR and FCR. The corresponding total sulphur amino acid requirements (Met + Cys) of this species were calculated to be 12.3 g kg?1 dry diet for SGR and FCR. DL‐Met supplementation in 50 g kg?1 FM diets showed a decreasing trend in plasma cholesterol contents (p < .05). No significant differences were observed in whole‐body composition, plasma protein, triglyceride and free EAA contents among dietary treatments, while plasma aspartate transaminase, albumin and ammonia contents were significantly influenced by dietary Met levels. Juvenile gibel carp grew equally well on 150 g kg?1 FM diet or 50 g kg?1 FM diets balanced for EAA profile with supplemental amino acids. The results of this study overall indicate that balancing dietary amino acid levels with DL‐Met supplementation is a key strategy in successfully reducing FM levels in the diets of gibel carp.  相似文献   

4.
An 11‐week growth trial was conducted to determine dietary myo‐inositol (MI) requirement for juvenile gibel carp (Carassius auratus gibelio). Myo‐inositol was supplemented to the basal diet to formulate six purified diets containing 1, 56, 107, 146, 194 and 247 mg MI kg?1 diet, respectively. Each diet was fed to triplicate groups of juvenile gibel carp (initial body weight 3.38 ± 0.27 g, mean ± SD) in a flow‐through system. The diets were randomly assigned to different fish tanks. Fish fed ≥ 107 mg MI kg?1 diet had significantly higher weight gain (WG), feed efficiency (FE) and protein efficiency ratio than those fed 1 mg MI kg?1 diet. Fish fed ≥ 56 mg MI kg?1 diet had higher feeding rate and survival compared with fish fed 1 mg MI kg?1 diet. Dietary supplemental inositol did not affect fish liver inositol concentration. Fish fed ≥ 56 mg MI kg?1 diet had higher body dry matter, crude protein and gross energy and lower hepatosomatic index than fish fed 1 mg MI kg?1 diet. Dietary inositol supplementation decreased fish body ash. Quadratic regression of weight gain indicated that the myo‐inositol requirement to maximum growth for juvenile gibel carp was 165.3 mg MI kg?1 diet.  相似文献   

5.
A 60‐day trial was conducted in a recirculation system to determine the responses of herbivorous grass carp (Ctenopharyngodon idellus) (0.43 g), omnivorous gibel carp (Carassius auratus gibelio CAS III) (0.46 g) and carnivorous black carp (Mylopharyngodon piceus) (0.46 g) when fed with fishmeal (FM)‐ or soybean meal (SBM)‐based diets. Two isonitrogenous (380 g kg?1 DM), isolipid (80 g kg?1 DM), isocaloric (17.75 kJ g?1) diets were formulated using FM and SBM as main protein sources. The results showed that weight gain (WG), feed efficiency (FE) and protein retention efficiency (PRE) in FM group were significantly higher than those in SBM group. Grass carp showed better utilization on SBM than other two species and presented higher WG, FE and PRE. When fed with SBM diet, intestinal chymotrypsin (CHY), lipase and trypsin (TRY) activities of gibel carp and black carp decreased while higher α‐amylase (α‐AMY) activity of grass carp increased. An enteritis‐like effect was observed in black carp and grass carp fed SBM diet. Intestine bacteria mainly belonged to Firmicutes in gibel carp and Proteobacteria in black carp. The dominant genera identified in three species were Cellulomonas, belonging to Actinobacteria. In conclusion, SBM decreased the growth of three carps. Grass carp was more adapted to plant protein.  相似文献   

6.
A 63‐day growth trial was undertaken to estimate the effects of supplemented lysine and methionine with different dietary protein levels on growth performance and feed utilization in Grass Carp (Ctenopharyngodon idella). Six plant‐based practical diets were prepared, and 32CP, 30CP and 28CP diets were formulated to contain 320 g kg?1, 300 g kg?1 and 280 g kg?1 crude protein without lysine and methionine supplementation. In the supplementary group, lysine and methionine were added to formulate 32AA, 30AA and 28AA diets with 320 g kg?1, 300 g kg?1 and 280 g kg?1 dietary crude protein, respectively, according to the whole body amino acid composition of Grass Carp. In the groups without lysine and methionine supplementation, weight gain (WG, %) and specific growth rate (SGR, % day?1) of the fish fed 32CP diet were significantly higher than that of fish fed 30CP and 28CP diets, but no significant differences were found between 30CP‐ and 28CP‐diet treatments. WG and SGR of the fish fed 32AA and 30AA diets were significantly higher than that of fish fed 28AA diets, and the performance of grass carp was also significantly improved when fed diets with lysine and methionine supplementation (P < 0.05), and the interaction between dietary protein level and amino acid supplementation was noted between WG and SGR (P < 0.05). Feed intake (FI) was significantly increased with the increase in dietary protein level and the supplementation of lysine and methionine (P < 0.05), but feed conversion ratio (FCR) showed a significant decreasing trend (P < 0.05). Two days after total ammonia nitrogen (TAN) concentration test, the values of TAN discharged by the fish 8 h after feeding were 207.1, 187.5, 170.6, 157.3, 141.3 and 128.9 mg kg?1 body weight for fish fed 32CP, 32AA, 30CP, 30AA, 28CP and 28AA diets, respectively. TAN excretion by grass carp was reduced in plant‐based practical diets with the increase in dietary protein level and the supplementation of lysine and methionine (P < 0.05). The results indicated that lysine and methionine supplementation to the plant protein sources‐based practical diets can improve growth performance and feed utilization of grass carp, and the dietary crude protein can be reduced from 320 g kg?1 to 300 g kg?1 through balancing amino acids profile. The positive effect was not observed at 280 g kg?1 crude protein level.  相似文献   

7.
A 75‐day experiment was conducted with juvenile gibel carp (Carassius auratus gibelio) (4.80 ± 0.01 g) to evaluate effects of dietary chitosan on fish growth performance, haematology, intestine morphology and immune response. Six isonitrogenous (crude protein: 383 g kg?1), isolipid (97.5 g kg?1) and isocaloric (gross energy: 16.7 kJ g?1) diets were formulated to contain 0, 1800, 4000, 7500, 10 000, 20 000 mg kg?1 chitosan, respectively. The results showed that the growth was depressed when the fish fed with 10 000 mg kg?1 chitosan. Serum cholesterol, triglyceride and low‐density lipoprotein decreased in 10 000 and 20 000 mg kg?1 chitosan. On day 75, blood leucocyte phagocytic activity respiratory burst and alternative pathway of complement haemolytic activity were enhanced in 4000 mg kg?1 chitosan. The number of goblet cell, intraepithelial lymphocyte of mid‐intestine and microvilli height of distal intestine increased at 4000 mg kg?1 dietary chitosan. Dietary chitosan modulated intestine microbiota, depressed pathogen bacteria Aeromonas veronii‐like and improved Cellulomonas hominis‐like, Bacillus oceanisediminis‐like and two uncultured bacterium‐like species on day 75. Dietary 7500 and 10 000 mg kg?1 chitosan enhanced the protection against Aeromonas hydrophila infection. In conclusion, oral administration of dietary 7500 mg kg?1 chitosan for 75 days is recommended for the survival of gibel carp.  相似文献   

8.
D. Xie  D. Han  X. Zhu  Y. Yang  J. Jin  H. Liu  S. Xie 《Aquaculture Nutrition》2017,23(5):1104-1112
A nine‐week feeding experiment was conducted in flow‐through system with gibel carp (43.8 ± 0.2 g) to study the effects of dietary available phosphorus (P) on growth, phosphorous digestibility and intestinal enzyme activities. Seven semipurified diets were formulated to contain 0.8 (the basal), 2.4, 3.6, 6.1, 7.4, 10.1 and 15.8 g available phosphorus kg?1 diet. The results showed that specific growth rate and feed efficiency increased with increasing dietary available P from 0.8 to 7.4 g P kg?1. Fish body ash increased with increasing dietary available P, while moisture, protein content or energy content had no difference. Total phosphorus waste discharging (TPW) increased with increased dietary phosphorous. Plasma glucose was higher in the fish fed with 7.4 g kg?1 P. Plasma triglycerides was lower in fish fed diets containing 6.1–10.1 g kg?1 P. No significant effects were observed in plasma P and Ca (p > .05). The activities of intestinal amylase, lipase and trypsin showed no difference, while AKP and Na+, K+‐ATPase activities decreased with increasing dietary available P. In conclusion, based on the regression between specific growth rate (SGR), P retention efficiency, feed efficiency (FE) and dietary available P, the available P requirements for on‐growing gibel carp were 10.69, 8.22 and 6.72 g kg?1, respectively.  相似文献   

9.
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   

10.
This experiment was conducted to investigate total aromatic amino acid requirement of juvenile grass carp Ctenopharyngodon idella. Six isonitrogenous and isoenergetic semipurified diets containing casein and gelatin with graded level of phenylalanine (7.8, 11.1, 14.4, 17.6, 21.7, 24.9 g kg?1 DM) were formulated. Each diet was randomly assigned to triplicate group of 30 fish (3.58 ± 0.002 g, mean ± SEM) each tank for 8 weeks. The highest weight gain (WG, %), final body weight (g) and specific growth rate were recorded when phenylalanine level was 17.6 g kg?1 of the diet. Fish muscle protein content, protein efficiency ratio (PER), feed conversion ratio and alanine aminotransferase were significantly affected by dietary phenylalanine level. The polynomial regression calculated using WG and PER indicated that the optimal dietary total aromatic amino acid (phenylalanine + tyrosine) requirement for juvenile grass carp was 24.4 g kg?1 of the diet, corresponding to 65.9 g kg?1 of dietary protein.  相似文献   

11.
A feeding trial was conducted to study the effect of dietary lipid on growth performance and heat‐shock protein (HSP70 and HSP60) response of white seabass (WSB), Atractoscion nobilis. Five diets were formulated to contain 440 g kg?1 protein from 300 g kg?1 fish meal, 240 g kg?1 soybean meal and 100 g kg?1 soy protein concentrate with different levels of lipid: 100, 120, 140, 160 or 180 g kg?1. At the end of the trial, heat shock response based on HSP70 and HSP60 was measured in liver and white muscle from fish at ambient temperature and temperature shock conditions. Final weight and percent gain were significantly higher for fish fed the 100 g kg?1 lipid diet than for fish fed the rest of the diets (P ≤ 0.05). Feed conversion ratio was lowest for fish fed the 100 g kg?1 lipid diet. The HSP70 and HSP60 responses were positively correlated to dietary lipid levels following temperature shock. At ambient temperature, HSP60 and HSP70 responses in muscle and HSP60 response in liver increased with dietary lipid level. Temperature shock significantly increased the HSP response of fish in all treatments. Results of this study demonstrated that a moderate (110–120 g kg?1) level of dietary lipids would be recommended for production diets but a higher dietary lipid level may be required for optimal stress tolerance.  相似文献   

12.
An 8‐week feeding trial was conducted to assess dietary protein and lipid levels on growth performance, feed utilization and body composition of juvenile red‐spotted grouper (7.85 ± 0.03 g fish?1). Nine semi‐purified diets were formulated containing varying protein levels (440–520 g kg?1, dry matter) and lipid levels (60–120 g kg?1, dry matter). The weight gain of juvenile Epinephelus akaara was affected by dietary protein (p = .005) and its interaction with dietary lipid (p = .020). Viscerosomatic index, intraperitoneal fat ratio and whole‐body lipid level increased with increasing dietary lipid level (p < .001). Nitrogen retention was not affected by dietary protein and lipid, while lipid retention decreased with increasing dietary lipid level (p < .001). The plasma blood urea nitrogen increased with increasing dietary protein level (p = .003). This study showed that diet with 520 g kg?1 protein and 60 g kg?1 lipid with 30.58 mg kJ?1 P:E provided a maximal growth for this species. Moreover, an increase in dietary lipid levels (from 60 to 90 g kg?1) could reduce the protein requirement (from 520 to 480 g kg?1) without affecting the growth performance, while higher fat deposition was observed in fish fed high‐lipid diets.  相似文献   

13.
An 8‐week feeding trial was conducted to determine the optimal dietary arginine requirement for juvenile swimming crab Portunus trituberculatus. Six isonitrogenous and isolipidic experimental diets were formulated to contain graded arginine levels which ranged from 15.9 to 33.0 g kg?1. Each diet was randomly assigned to triplicate groups of 60 juvenile swimming crabs (4.72 ± 0.12 g). The results indicated that dietary arginine had significant effects on weight gain (WG), specific growth rate (SGR), protein productive value, feed efficiency and protein efficiency ratio. Weight gain and SGR significantly increased with the dietary arginine increasing from 15.9 to 27.4 g kg?1, while with the further increasing from 27.4 to 33.0 g kg?1, WG and SGR did not increase significantly. Maximum arginine, proline and total essential amino acid contents in muscle were observed in 27.4 g kg?1 group diet. The swimming crab fed the diet with lower dietary arginine level showed higher AST and lower ALT in the serum. Crab fed with the lower dietary arginine level had significantly lower ALT in the serum than the other groups. Haemolymph indexes were significantly affected by the dietary arginine level except for the cholesterol concentration, and the highest values were all found in 27.4 g kg?1 group diet. The two slope broken‐line model using SGR showed that the optimal dietary arginine requirement was 27.7 g kg?1 of the dry matter (56.0 g kg?1 dietary protein) for juvenile swimming crab.  相似文献   

14.
A 62‐day growth trial was conducted to determine the dietary Met requirement of the pre‐adult gibel carp (Carassius auratus gibeilo) (initial weight of 51.0 ± 0.02 g). Six isonitrogenous and isoenergetic diets using fish meal, blood meal and pea protein concentrate as protein sources supplemented with crystalline amino acids were formulated to contain graded levels of dietary Met (4.44, 6.56, 8.55, 10.90, 12.79 and 15.05 g kg?1, respectively) at a constant dietary cystine level of 3.99 g kg?1. The results showed that weight gain rate and protein productive value significantly increased with the dietary Met levels from 4.44 to 8.55 g kg?1, then reached plateau at 10.90 g kg?1. Plasma HDL‐C and TC were increased with dietary Met levels. Fish supplied with 4.44–8.55 g kg?1 Met showed lower plasma AST level than that of other groups. Plasma TG, LDL‐C and ALT levels were stable for all treatments. The activity of intestinal γ‐GT was increased with dietary Met levels. The optimal requirement of Met for pre‐adult gibel carp (>50 g) was a range from 7.86 g kg?1 to 9.84 g kg?1 dry diet or 16.9 g kg?1 to 23.0 g kg?1 of dietary protein with the presence of 3.99 g kg?1 Cys for the satisfied lipid metabolism and maximum growth, respectively.  相似文献   

15.
Oriental river prawn (Macrobrachium nipponense) has been widely cultured in Asian countries. However, its nutritional studies are very limited. In the present 8‐week study, we investigated the effects of dietary protein to energy ratio (P/E ratio) on the growth, feed utilization and body composition in juvenile M. nipponense (initial weight 0.302 ±0.03 g). Two‐factor experiment was designed and nine semi‐purified diets were formulated to contain three lipid levels (20, 80 and 140 g kg?1) and three protein levels (330, 380 and 430 g kg?1), producing P/E ratios from 16.5 to 23.4 mg KJ?1 protein. The results indicated that the growth, survival rate and protein efficiency were dose dependently improved by the increased dietary lipid, but not dietary protein content. Increased dietary lipid content and/or protein content increased lipid accumulation in whole body, hepatopancreas and muscle, but did not change the feed intake and hepatopancreas weight. In conclusion, our present study indicated that M. nipponense is a species with relatively high‐energy requirement. It could utilize dietary lipid content up to 140 g kg?1, while the dietary protein with more than 330 g kg?1 would not promote growth and protein efficiency. Taken together, 330 g kg?1 dietary protein and 140 g kg?1 dietary lipid level with P/E ratio 16.49 could be optimum for M. nipponense.  相似文献   

16.
W. Li  X. Wen  Y. Huang  J. Zhao  S. Li  D. Zhu 《Aquaculture Nutrition》2017,23(5):1035-1047
A two‐factor experiment was designed to determine the suitable dietary protein and lipid levels for juvenile Nibea diacanthus. Nine extruded pellet diets were formulated to contain three levels of protein (420, 470 and 520 g kg?1) and three levels of lipid (70, 110 and 150 g kg?1). Each diet was randomly fed to triplicate groups of 25 juvenile N. diacanthus (initial weight 12.12 ± 0.23 g) for 8 weeks in net cages. The results showed that weight gain rate (WGR), specific growth rate, final body weight and energy retention were significantly influenced by the dietary protein and lipid levels‐. The highest WGR (982.5g kg?1.) of N. diacanthus was found in the group with dietary protein and lipid of 520 and 150 g kg?1. Feed intake and feed efficiency were significantly impacted by the dietary protein levels. An interactive effect between dietary protein and lipid on the protein retention and protein efficiency ratio was observed. There were no significant differences in condition factor and survival among all treatments. Hepatosomatic index and viscerasomatic index of N. diacanthus were positively related with dietary lipid levels, but negatively with dietary protein levels. Crude protein, crude lipid, ash, moisture and energy contents of the whole body, muscle and liver were influenced by dietary protein and lipid levels. Moreover, total essential amino acid pattern of the muscle was correlated to those of dietary protein. Total protein concentration in the serum was affected by dietary protein and lipid levels. Meanwhile, both serum cholesterol and triglyceride concentrations increased with increasing dietary lipid levels. These results demonstrate that the diet containing 470 g kg?1 protein and 110 g kg?1 lipid is optimal for juvenile N. diacanthus and analysis of WGR by quadratic regression indicated that the estimated optimal protein‐to‐energy ratio for juvenile N. diacanthus was 24.53 mg protein kJ?1.  相似文献   

17.
Juvenile mirror carp were fed with five different diets containing 303, 322, 341, 361 and 379 g kg?1 protein and reared at three different water temperatures (18, 23 and 28 °C) for 60 days. We investigated the insulin‐like growth factor I (IGF‐I) mRNA expression, growth performance and the relationship between IGF‐I mRNA expression and the growth performance. The results indicated that the IGF‐I mRNA expression, final body weight, specific growth rate (SGR) and feed efficiency (FE) were enhanced significantly with increasing dietary protein levels (P < 0.05), whereas the protein efficiency ratio, hepatosomatic index (HSI) and viscerosomatic index (VSI) were decreased. Moreover, the IGF‐I mRNA expression, final body weight and SGR were increased significantly with temperature, whereas the HSI and VSI indices were decreased significantly with temperature. Correlation analysis showed that the IGF‐I mRNA expression levels in the brain and liver were positively related to the SGR and FE growth indices (P < 0.01). Finally, the optimal protein requirements for fish growth in different seasons were determined based on the values of SGR and FE, that is 343–348 g kg?1 protein at 18 °C, 354–352 g kg?1 at 23 °C and 371–362 g kg?1 at 28 °C. In this way, we can adjust the dietary protein levels according to culture temperature to reduce any negative impacts on dietary costs and environmental pollution.  相似文献   

18.
Twelve experimental diets (D‐1 to D‐12) in a 4 × 3 factorial design (four protein levels: 250, 350, 400 and 450 g kg?1 and three lipid levels: 50, 100 and 150 g kg?1) were formulated. Carbohydrate level was constant at 250 g kg?1. Rohu fingerlings (average wt. 4.3 ± 0.02 g) were fed the experimental diets for 60 days in three replicates at 2% BW  day?1. Weight gain (%), specific growth rate (% day?1) and feed gain ratio (FGR) indicated that diets containing 450 g kg?1 protein and 100 or 150 g kg?1 lipid (diets D‐11 and D‐12) resulted in best performance, although results were not significantly different from those of diet D‐9 (400 g kg?1 protein and 150 g kg?1 lipid). Protein efficiency ratio was highest with diets D‐6 (350 g kg?1 protein and 150 g kg?1 lipid) and D‐9 (400 g kg?1 protein and 150 g kg?1 lipid) (P > 0.05) and declined with higher and lower protein diets at all levels of lipid tested. Elevated lipid level (50, 100 or 150 g kg?1) did not produce better FGR in diets containing 400 and 450 g kg?1 dietary protein (P > 0.05). The combined effects of protein and lipid were evident up to 400 g kg?1 protein. Growth and FGR showed consistent improvement with increased lipid levels from 50 to 150 g kg?1 at each protein level tested except with diets containing 450 g kg?1 protein. Apparent nutrient digestibility (for protein, lipid and energy) did not show significant variation among different dietary groups (P > 0.05). Whole body protein and lipid contents increased significantly (P > 0.05) with dietary protein level. The results of this study indicate that rohu fingerlings are adapted to utilize high protein in diets with varying efficiency. The fish could utilize lipid to spare protein but there is no significant advantage from this beyond the dietary protein level of 350–400 g kg?1 in terms of growth and body composition.  相似文献   

19.
Six hundred Labeo rohita (average weight, 6.78 g) were distributed in 24 tanks (25 fish per tank), which were allotted to eight experimental groups in triplicates. Half of the experimental groups were maintained at ambient water temperature of 26 °C, whereas the other half were exposed to 32 °C for 1 week then later maintained at 26 °C for 4 weeks. Fish reared under different temperature regimes were fed one of the four diets containing 200 g kg?1, 300 g kg?1, 400 g kg?1 or 450 g kg?1 protein. Growth, feed efficiency and protein retention were higher at 32 °C and continued for the next 2 weeks after decreasing the temperature. The dietary protein level and water temperature interactions were more effective in modulating the response of hepatic glucokinase than that of hexokinase and pyruvate kinase. In contrast, hepatic gluconeogenesis was not affected by rearing temperature. Hepatic aspartate aminotransferase and alanine aminotransferase activity was found higher (P < 0.05) at low temperature and at high protein level. It is suggested that the metabolic activities of fish are triggered by short‐term exposure to higher temperature and the increased metabolic activity extended for a duration of 3 weeks during which 400 g kg?1 dietary protein level was found to support growth of fish.  相似文献   

20.
A feeding experiment was conducted to determine the dietary zinc (Zn) requirement of hybrid tilapia fed on a diet with soya bean meal as the sole protein source. The quantity of phytic acid in the experimental diet was 15.5 g kg?1. Juvenile hybrid tilapia were fed on diets containing 31–227 mg Zn kg?1 in triplicates for 6 weeks. Haematology of the fish was not affected by various dietary Zn levels. Fish fed on a diet containing 31 mg kg?1 endogenous Zn showed the lowest growth rates, feed utilization, and body and plasma Zn levels. Weight gain (WG), plasma Zn level and superoxide dismutase (SOD) activity increased when a higher quantity of dietary Zn of 127 mg kg?1 was administered to the experimental fish. Beyond this level, the values of these parameters were relatively stable. On the other hand, within the dietary Zn range tested, whole‐body Zn and ash increased with higher dietary Zn levels. Analysis using a broken‐line model showed that the dietary Zn requirements of hybrid tilapia fed on soya bean meal‐based diets containing 15.5 g kg?1 endogenous phytic acid were 115, 115 and 105 mg kg?1 based on WG, whole‐body Zn retention and plasma Zn level, respectively.  相似文献   

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