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1.
Four isoenergetic (21 kJ/g dry matter, DM) and isolipidic (65 g/kg DM) diets containing different crude protein/total carbohydrate (CHO) ratios: 60/26, 56/30, 52/34 and 48/38, were tested in 22 g Senegalese sole for 104 days. Apparent digestibility coefficients (ADC) were not affected by the treatments, and all groups presented extremely low starch ADC values (22.8%–36.5%). Replacement of dietary protein by CHO did not affect daily growth index (0.9–1.0), but significantly increased voluntary feed intake of fish. Regression analyses demonstrated that digestible protein content, rather than digestible energy, was the main dietary factor influencing such feeding activity (R2 = .952). A significantly increased feed conversion ratio was observed in sole fed increasing CHO contents. The dietary protein/CHO ratio did not influence whole‐body composition. Sole fed the 48/38 diet showed the lowest efficiency in terms of N and energy utilization. PUFA were the most represented fatty acid fraction in fillet, regardless of the dietary protein/CHO ratio, mainly due to the high content of DHA. Senegalese sole increase feed intake under low dietary protein/CHO ratios to ensure an adequate N intake. Such compensatory mechanism seems to be triggered to satisfy a specific protein metabolic requirement for energy purposes as tissue accretion remained unchanged.  相似文献   

2.
The dietary total and available requirement of tryptophan of Nile tilapia fingerlings was determined using linear regression analysis. Six hundred fish (3.4 ± 0.0 g) were fed diets containing 296.4 g/kg of crude protein and 14.1 MJ/kg of digestible energy. Five extruded diets containing 2.5, 3.0, 3.4, 3.8 and 4.2 g/kg of total tryptophan were evaluated. Fish were fed four times a day during 45 days. Final body weight, weight gain, feed intake, feed conversion ratio and net protein utilization of fish fed Trp 3.4 and Trp 3.8 diets were improved compared to fish fed Trp 2.5 and Trp 4.2 diets. No significant differences in survival rate, whole‐body moisture and ash were observed. Whole‐body amino acid profile of fish fed different diets did not differ statistically (p > .05). Fish fed Trp 3.0 and Trp 3.4 diets showed higher tryptophan retention compared to fish fed Trp 2.5 and Trp 4.2 diets. Excepting blood glucose, no effects of dietary tryptophan on haematological parameters were observed. The dietary total tryptophan requirement of Nile tilapia fingerlings based on weight gain was estimated to be 3.4 g/kg (11.0 g/kg of dietary crude protein) or 3.0 g/kg of available tryptophan (11.0 g/kg of dietary digestible protein).  相似文献   

3.
An 8‐week feeding trial was conducted to investigate the effects of dietary carbohydrate‐to‐lipid (CHO:L) ratios on growth, liver and muscle glycogen content, haematological indices, and liver and intestinal enzyme activity of juvenile grouper (Epinephelus coioides). Five isonitrogenous (496.0 g/kg protein) and isoenergetic (21.6 KJ/g gross energy) diets with varying CHO:L ratios of 0.65 (D1), 1.31 (D2), 2.33 (D3), 4.24 (D4) and 8.51 (D5), respectively, were fed to triplicate groups of 20 fish (average 10.02 ± 0.1 g) for 8 weeks. Results showed that the weight gain rate, specific growth rate and protein efficiency ratio (PER) of juvenile grouper increased first and then decreased with the increase in CHO:L ratio, reaching a maximum value in the D4 (CHO:L = 4.24) diet. The trend for the feed conversion ratio was opposite to the PER. Along with the diet CHO:L ratios, the apparent digestibility coefficients (ADC) of crude lipid and energy for the juvenile groupers decreased gradually, while the ADC of dry matter, liver and muscle glycogen level increased gradually. Total protein, triglycerides and cholesterol in serum were all maximized in the D4 diet and glucose in the D5 (CHO:L = 8.51) diet. Digestive enzyme activity in the intestine was significantly affected by dietary CHO:L ratio. Liver hexokinase, phosphofructokinase and glucose‐6‐phosphate dehydrogenase activity increased significantly as CHO:L ratio increased. Liver lysozyme and acid phosphatase activity in the groupers fed the D3 (CHO:L = 2.33) diet was significantly higher than that of other diets. Liver fructose‐1,6‐bisphosphatase and alkaline phosphatase activity reached a maximum value in the D4 diet and was significantly higher than that in the D1 diet. Taking the above results together, it can be concluded that an optimal dietary CHO:L ratio of 2.33 is suitable for grouper culture concerning growth performance and health.  相似文献   

4.
为探讨糖脂比对吉富罗非鱼幼鱼生长性能、血液生化指标和肝脏糖代谢关键酶的影响,本实验设计了5种不同糖脂比(1.5、2.3、3.9、7.0、16.5)的等氮等能饲料,以吉富罗非鱼幼鱼为实验对象,进行了为期8周的饲养实验。结果显示,随饲料中糖脂比升高,吉富罗非鱼特定生长率(SGR)、增重率(WGR)和蛋白质效率(PER)先升高后降低,糖脂比为3.9和7.0时,WGR、SGR和PER最高。饵料系数(FCR)的变化趋势与此相反,在糖脂比为3.9和7.0组显著低于其他组。随着饲料糖脂比的增加,吉富罗非鱼全鱼粗脂肪含量逐渐下降,在糖脂比为16.5时达到最低水平,但仅与1.5组存在显著差异。血浆甘油三酯在糖脂比最高组也出现显著降低,血浆胆固醇同样在糖脂比最高组显著低于3.9组。然而血糖的变化趋势相反,当糖脂比为16.5时显著高于其他组。随着糖脂比的升高,吉富罗非鱼幼鱼肝脏中丙酮酸激酶(PK)的活性及mRNA表达量逐渐升高,而磷酸烯醇式丙酮酸羧激酶(PEPCK)的活性及mRNA表达水平则逐渐下降。根据二次回归模型得出,在等氮等能的饲料条件下,吉富罗非鱼幼鱼最适宜的糖水平和脂肪水平分别为49.69%和9.53%,其对应的糖脂比为8.4。  相似文献   

5.
A growth experiment was conducted to determine the optimal carbohydrate‐to‐lipid (CHO: L) ratio for juvenile yellowfin seabream cultured in 340‐L indoor recirculating tanks. Seven isonitrogenous (450 g kg−1 dietary protein) and isoenergetic (14.1 MJ kg−1) diets with increasing CHO: L ratios (0.03–5.09 g: g) were fed to triplicate groups of 30 fish with an initial weight of 4.91 g for 56 days. Fish were fed to satiation twice a day and the water temperature ranged between 28 and 31.7 °C during the experimental period. Survival was high in all the groups and was not affected by dietary treatments. Best weight gain (WG) and specific growth rate (SGR) were observed in fish fed diets with CHO: L ratios of 0.29 and 0.72, which were not significantly different from that of 0.03, 1.26 and 1.92, but apparently higher than that of 3.22 and 5.09. Feed efficiency (FE), protein efficiency ratio (PER) and protein production value (PPV) followed the same general pattern as WG and SGR. Highest level of energy production value (EPV) was found in fish fed diets with CHO: L ratio of 0.72. Proximate compositions of fish whole body and tissues were markedly affected by dietary CHO: L ratios. Whole body, muscle and liver lipid increased as CHO: L ratios decreased, whereas moisture contents were reduced. Dietary CHO: L ratios had no significant effect on protein content in whole body and muscle. Plasma total cholesterol levels of fish fed diets with CHO: L ratios less than 0.72 were significantly higher than those of the other groups. Triacylglyceride levels decreased linearly as dietary CHO: L ratios increased. Viscerosomatic index (VSI) significantly increased as dietary CHO: L ratios decreased. Intraperitoneal fat ratio (IPF) of fish fed diets with CHO: L ratios less than 1.92 were significantly higher than those fed CHO: L ratios of 3.22 and 5.09. Hepatosomatic index (HSI) did not vary between the test diets. Based on second‐order polynomial regression analysis of WG against dietary carbohydrate and lipid levels, 84.1 g kg−1 of carbohydrate and 136.3 g kg−1 of lipid, corresponding to a CHO: L ratio of 0.62, in a diet holding 450 g kg−1 of crude protein and 14 KJ g−1 of metabolizable energy, proved to be optimal for juvenile yellowfin seabream.  相似文献   

6.
The present study was conducted to evaluate the interaction of protein and energy ratio in low protein (20, 25 and 30 %) diets for juvenile Nile tilapia (Oreochromis niloticus) (initial weight 7.44 ± 0.03 g). Dietary protein to energy (P/E) ratio of nine practical diets ranged from 66.84 to 115.14 mg protein/kcal energy. Each diet was randomly assigned to four replicate groups of fifteen fish. After 10 weeks, Fish fed the lowest dietary protein (20 %) and lowest energy (2,600 kcal/kg) diets were significantly smaller than fish maintained on D5 (25/2800) and D6 (30/2800), However, there were no significant differences among all the treatments except D1. The whole body moisture and protein levels were significantly influenced by dietary protein and energy content. Whole body energy content and digestible energy retention were significantly influenced by energy content of the diet. Conversely, dietary protein level significantly influenced protein retention but it did not influence digestible energy retention. Under the reported conditions, the response of tilapia to dietary energy or protein was seen only at the lower levels of inclusion and tilapia demonstrated limited protein sparing as dietary energy was increased. However, this did modify the carcass composition through higher dietary energy.  相似文献   

7.
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   

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

9.
This study was conducted to evaluate the use of low protein diets for channel catfish Ictalurus punctatus raised in earthen ponds at high density. Fingerling channel catfish were stocked into 0.04-ha earthen ponds at a rate 24,700 fish/ha and fed experimental diets daily to satiation from April to October 1995. The five diets contained either 32, 28, 24, 20, or 16% crude protein with digestible energy to protein (DE:P) ratios ranging from 8.9 to 16.2 kcal/ g protein. Weight gain was not different among channel catfish fed diets containing 32, 28, or 24% crude protein. Fish fed diets containing 20% or 16% crude protein gained less weight than fish fed the diets containing 28% or 24% crude protein, but not statistically less than the fish fed the 32% crude protein diet. Feed consumption data followed similar trends as weight gain data. Feed conversion ratio increased linearly as dietary protein decreased, but was not significantly different (multiple range test) for fish fed diets containing either 32% or 28% crude protein. There were no differences in survival and hematocrit of fish fed the different diets. No differences (multiple range test) were observed in dressout percentages for fish fed the various diets, but dressout percentage tended to decrease linearly as dietary protein decreased. Visceral fat and fillet fat increased and fillet protein and moisture decreased linearly as dietary protein decreased. Results from this study indicated that dietary protein concentrations as low as 24% are adequate for maximum weight gain of pond-raised channel catfish fed daily to satiation. Fish fed dietary protein levels below 24% grew relatively well, particularly considering that dietary protein was reduced 40–50% below that typically used in commercial channel catfish feeds. However, dietary protein levels below 24% may increase fattiness to an unacceptable level presumably because of the high digestible energy to protein ratio.  相似文献   

10.
Apparent digestibility coefficient (ADC) values for a number of ingredients of plant or animal origin were obtained in order to formulate diets based on such values and to evaluate growth performance of Nile tilapia Oreochromis niloticus fed four experimental diets in which fish meal was gradually replaced by a mixture of other ingredients.The digestibility of various diet components was measured by using an inert marker in the feed and by using the Guelph faeces collecting system. ADC values of the ingredients tested were generally high, especially for fish meal. It was found that extruded pea seed meal (92.6%), defatted soybean meal (94.4%), full-fat toasted soybean (90.0%) and micronized wheat (88.6%) were the best vegetable proteins tested. Lupin seed meal and faba bean meal had similar ADC values for protein and energy.Groups of tilapia, initial mean body weight (SD) 6.7 (0.1) g, were fed experimental diets with the same digestible protein (DP) and digestible energy (DE) containing graded levels of a mixture of vegetable ingredients as partial or total replacement of fish meal protein. A growth trial was conducted over 12 weeks as partial or total replacement of fish meal protein. A growth trial was conducted over 12 weeks at a water temperature of 25 °C. Significant differences were observed for weight gain among tilapia fed diets D0, D33, D66 and D100 (containing only animal protein, 33, 66, and 100% of plant protein, respectively). No significant differences were observed for voluntary intake among tilapia fed diets D0, D33 and D66. These values were significantly lower than those observed for tilapia fed plant protein based diet (D100) and suggest the possibility of partial replacement of fish meal by vegetable proteins without negative effects.  相似文献   

11.
The effect of dietary protein level on the apparent digestibility coefficient (ADC) of meat and bone meal and rapeseed meal for Nile tilapia Oreochromis niloticus L. was examined. Three reference diets were formulated to contain 240 (RD24), 350 (RD35) and 450 (RD45) g kg?1 crude protein, and chromic oxide was added at 10 g kg?1 in the reference diets as an inert indicator. Six test diets were formulated by mixing one of the reference diets with each test ingredient at a ratio of 70:30. Fish (initial body weight 101.0 ± 0.6 g) were fed reference diets for 3 days and then fed test diets in the following 4 days cyclically for 4 weeks. Faeces of fish fed each reference diet or test diet was collected from the third day of each diet conversion. Dietary protein level significantly affected the ADC of protein and energy of reference diets, test diets and test ingredients. The ADC of protein and energy of meat and bone meal and rapeseed meal was the highest when these ingredients were mixed with diet RD35. The scope of variation in the ADC of protein and energy of meat and bone meal was 8% (from 69.9% to 78.3%) and 8% (from 70.2% to 78.0%), and the scope of variation in the ADC of protein and energy of rapeseed meal was 4% (from 79.8% to 83.3%) and 5% (from 56.0% to 60.7%) when the dietary protein level was increased from 300 to 480 g kg?1. This indicates that the ADC of protein and energy of meat and bone meal and rapeseed meal for Nile tilapia varied considerably at different dietary protein levels.  相似文献   

12.
An experiment was conducted to determine the effect of dietary wheat starch on grass carp (Ctenopharyngodon idella) in terms of growth performance, feed efficiency and digestibility. Five isoproteic (23.5%) and isolipidic (5.7%) diets with five supplemented levels of wheat starch (D20, D26, D33, D40 and D47 with 20, 26, 33, 40 and 47%, respectively) were fed to triplicate groups of grass carp (mean initial wet weight 6.9 ± 0.1 g) for 8 weeks. Results showed that weight gain (WG, %), feed efficiency (FE, %) and protein efficiency ratio (PER) in D20, D26 and D33 treatments were significantly higher than those in D40 and D47 treatments (P < 0.05). Digestibility of carbohydrate and protein was significantly higher in D20, D26 and D33. No significant differences were found in serum glucose and triglyceride contents between treatments. Serum lipase activity of fish fed D40 and D47 was significantly higher than that of fish fed other diets. Whole-body, muscle and liver lipid contents increased with dietary starch level as did mesenteric fat index, hepatosomatic index and viscerosomatic index. In conclusion, when dietary protein level was 23%, the level of dietary wheat starch should maximum be 33% to support normal growth of grass carp. Fish growth was hampered by higher wheat starch (>33%) despite fish ate increasing levels of dietary digestible energy. Furthermore, excess digestible carbohydrate was to some extent converted to lipid that was deposited in various tissues. Most importantly, grass carp could endure high levels of cellulose without any negative effect on growth and digestibilities of dietary protein and carbohydrate.  相似文献   

13.
This study compared the ability of juvenile non-transgenic (NT) and transgenic growth hormone (T; gene construct OnMTGH1) coho salmon (Oncorhynchus kisutch) to metabolically utilize energy from lipid and carbohydrate for growth at two dietary protein concentrations. Triplicate groups of size-matched (initial weight, 28.2–29.1 g) NT and T salmon held in 10.5–10.8 °C well water on a natural phototocycle (12.25 h → 8.25 h) were each fed one of four isoenergetic (~ 17.5 MJ of digestible energy (DE)/kg) dry diets twice daily to satiation for 83 days. These diets contained 340 g (LP) or 430 g (HP) of estimated digestible protein (DP)/kg and either 123 g (LL) or 164 g (HL) of estimated digestible lipid (DL)/kg at each DP level (dry weight basis). Estimated digestible carbohydrate (DCHO) concentrations ranged from 45 to 269 g/kg to equalize dietary DE. Under the preceding conditions 46–66% of NT and 18.7–27.5% of T coho, depending upon diet treatment, exhibited no growth or lost weight during the study. NT coho are known to grow slowly or lose weight between the fall equinox and winter solstice but this was unexpected for T coho. Considering all fish T coho, regardless of diet treatment, exhibited significantly higher specific growth rates (SGR) than NT fish due to enhanced feed intake, feed and protein (gross and available deposited) utilization and generally improved available energy utilization. Diet treatment did not affect the growth performance of T fish. Within NT fish, the HP diets supported best gross and available protein and energy utilization. SGR values for growing fish (FG) only followed identical trends to those for all fish in relation to diet treatment. Regardless of fish genotype, terminal hepatosomatic indices for FG were directly related to dietary DCHO content and maximum values were noted in NT fish fed LP–LL (significantly higher than observed in NT or T fish fed HP–HL). Final whole body protein concentrations adjusted for dissimilar fish size were higher in T fish fed HP–HL than in T fish fed LP diets and NT fish fed LP–LL. This was also true for T fish fed HP–LL versus T fish fed the LP diets. Within HP groups, whole body lipid and energy contents were generally higher in NT versus T fish whereas within the LP groups energy content was significantly higher in T versus NT fish and was highest in T fish fed LP–LL. Terminal plasma titres for GH and IGF–1 (all fish) were significantly higher in T than in NT fish and were generally uninfluenced by diet treatment. Non-growing NT and T fish had elevated GH relative to NT and T fish that grew. Also, GH was higher in growing T fish relative to growing NT fish whereas the opposite was true in non-growing fish. Plasma IGF-1 levels were higher in growing NT and T fish than in their respective non-growing counterparts. Within FG only, IGF-1 levels were higher in T versus NT fish.It is concluded that T coho have enhanced ability to effectively utilize DE from DCHO relative to NT fish especially when DP is near the bottom of the optimal range and DL is concurrently suboptimal for NT fish. This is likely due to the elevated titres of GH, IGF-1 and 3,5,3′-triiodo-l-thyronine (measured in another study) in T fish. Also, the enhanced ability of T fish to store energy under these dietary conditions suggests enzymatic improvements in their anaerobic and aerobic metabolism of glucose.  相似文献   

14.
This research assessed four levels of crude protein—200, 250, 300 and 350 g/kg—associated with two crude lipid concentrations—110 and 140 g/kg—in diets for juveniles of tambatinga (♀Colossoma macropomum × ♂Piaractus brachypomus) over 63 days. The fish (15.2 ± 0.2 g) were distributed in 24–160 L tanks (11 fish/tank) in a 4 × 2 completely randomized factorial design (n = 3). Increasing the lipid content in the diets reduced (p < 0.05) the protein requirements for weight gain from 326 g/kg (diets with 110 g/kg LIP) to 255 g/kg (diets with 140 g/kg). Protein retention in the fish increased (p < 0.05) when they were fed up to 293 g/kg CP and 140 g/kg LIP; in the diets with 110 g/kg LIP, protein retention decreased linearly (p < 0.05) as the protein content in the diets increased. Feed efficiency increased (p < 0.05) when the fish received up to 308 g/kg CP regardless of lipid concentration (p > 0.05). In conclusion, tambatinga juveniles at 15–120 g have a minimum requirement of 255 g/kg CP and 140 g/kg CL and a protein:energy ratio of 17.4 g CP kJ/digestible energy (DE).  相似文献   

15.
A 154‐day trial was performed to assess the use of an alternative protein blend (corn gluten, krill and meat meal) as a substitute for fishmeal in diets for juvenile yellowtail, using four isolipidic (140 g/kg) and isoenergetic diets (24 MJ/kg) with the same digestible protein content (50%). The control diet was FM100, without replacement, and in FM66, FM33 and FM0, fishmeal was replaced at 33 g/kg, 66 g/kg and 100 g/kg, respectively. At the end of the experiment, no differences in growth parameters were observed. Fish fed the FM0 diet exhibited the lowest survival (23%). This high mortality may be due to different factors, such as a dietary amino acid imbalance or some antinutrient factors contained in the alternative ingredients. Feed intake, feed conversion ratio, digestible protein intake and protein efficiency ratio were similar in all diets. However, digestible energy intake and protein efficiency retention were lowest in fish fed the FM0 diet. Apparent digestibility coefficients for protein, energy and amino acids diminished as a substitution for fishmeal increased. Significant differences were observed in the diet whole‐fish body profile amino acid retention (AAR) ratio for the seven essential amino acids. In summary, total fishmeal replacement by the blend assayed was not feasible for yellowtail. The FM66 diet resulted in good growth, high survival and good nutrient efficiency.  相似文献   

16.
The apparent digestibility coefficients (ADC) of poultry by-product meal-pet food grade (PBM) and porcine meal (PM) were determined for fingerling male Nile tilapia. ADC for protein were 98.1% and 92.3% in PBM and PM, and 87.1% and 79.4% for energy. PBM and PM were then used as complete replacements for fish meal (FM) in practical diets for Nile tilapia formulated to contain equal digestible protein (300 g kg−1) and energy (16.74 MJ per 100 g) on an as-fed basis. Fingerlings (mean initial weight ±SD, 9.5 ± 0.015 g) were fed for 8 weeks on one of the four diets: FM-, PBM- or PM-based and a commercial feed. The ADC for protein in control and PBM diets (89.7% and 87.9%) were significantly higher than those for the control diet (81.96%). Growth performance and feed utilization were statistically similar between fish fed control and PBM diets, whereas the PM diet exhibited significantly lower performance compared with the control. However, the PM diet showed similar results to the commercial reference diet. Survival and feed conversion ratio were not significantly influenced by replacement of FM with either PBM or PM. The results indicated that PBM and PM can effectively replace FM in practical diets for fingerling Nile tilapia.  相似文献   

17.
This study investigated the influence of different dietary protein/carbohydrate ratios on activities of enzymes involved in the amino acid metabolism as well as on growth performance and body composition of Nile tilapia (Oreo- chromis niloticus). Fish were fed semi-synthetic diets differing in their protein/carbohydrate ratio. The diets were formulated to be isolipidic and isoenergetic (on the basis of metabolizable energy). Fish were reared individually. After a prefeeding phase, tilapia were randomly assigned to three groups and were fed the experimental diets at a relatively low level. The study lasted 9 weeks. Proximate composition, gross energy content, and activities of aspartate aminotransferase (ASAT) and alanine aminotransferase (ALAT) in the liver of fish were determined. While the mean growth rate and feed conversion efficiency did not differ significantly among the feeding groups, the body composition showed significant differences. The dietary protein/carbohydrate ratio had no significant effect on the protein and energy gain, but the lipid gain was significantly higher in tilapia fed the low-protein diet. The activities of ASAT and ALAT per gram of liver and per gram of soluble protein were significantly increased in fish fed the high-protein diet. There was a significant positive correlation between the activities of ASAT and ALAT. The activities of both enzymes in the liver were significantly higher in fish with a higher protein gain. Measuring the activities of enzymes involved in the amino acid metabolism can provide more information about the metabolic utilized dietary protein.  相似文献   

18.
Knowing the effect of dietary nutrients on physiological parameters, especially oxidative stress, during fish rearing can be useful to improve fish health and optimize production in aquaculture. In this study, four iso‐energetic (2 × 2 factorial design) diets differing in nutrient composition were submitted to the Siberian sturgeon juveniles, to analyse biochemical and physiological responses. The juveniles were fed for as long as 10 weeks with the following diets: low protein–high carbohydrate (CHO): lipid ratio (LP‐St), high protein–high CHO: Lipid ratio (HP‐St), low protein‐low CHO: Lipid ratio (LP‐L) and high protein‐low CHO: Lipid ratio (HP‐L). It was shown that HP‐L diet significantly induced higher growth performance in the juveniles than LP‐L; however, there was not a significant difference between them with other treatments. HSI was increased by higher dietary CHO: L ratio. The result obviously showed the higher dietary fat led to an increase in sturgeon body fat content. In addition, dietary protein and CHO: lipid ratio significantly affected plasma metabolites (glucose, cortisol, cholesterol and triglyceride) but did not affect IGF‐1 and insulin levels. Based on enzyme activities results, incorporation of high protein (44%) in the diet induced lower amylase activity and carbohydrate digestion in the sturgeon juveniles. Moreover, antioxidant enzyme activities in this species were more influenced by lipid than other nutrients. In conclusion, using appropriate carbohydrates (~30%) in the sturgeon diet helps to spare protein. Furthermore, it is suggested to decrease the amount of lipid in high protein diet, to improve higher sturgeon fillet quality and less oxidative damage in liver.  相似文献   

19.
Ten isonitrogenous casein–gelatin‐based diets were formulated to contain five estimated metabolizable energy concentrations (10.92, 12.29, 13.63, 14.82 and 16.16 kJ g?1) at two carbohydrate‐to‐lipid ratios (CHO : L, 5.3 and 12.8, g : g) in a 5 × 2 factorial arrangement. Each diet was assigned to triplicate groups of 11 piracanjuba fingerlings (5.25 ± 0.14 g) and fed to apparent satiation twice a day for 90 days. Higher daily weight gain was obtained by fish fed the 13.63 kJ g?1 diets for both CHO : L ratios. There was a significant reduction of feed consumption when dietary energy concentration increased above 13.63 kJ g?1. Feed conversion ratio and apparent net energy retention improved as dietary energy increased. Apparent net protein retention tended to be lower in the highest and lowest dietary energy concentrations. The results suggest that dietary lipid energy was more efficiently utilized by piracanjuba fingerlings than carbohydrate energy. Body composition and hepatosomatic index (HSI) were not influenced by dietary CHO : L ratio. However, an increase in dietary energy concentration beyond 13.63 kJ g?1 resulted in a significant increment in lipid deposition, while body moisture and HSI decreased. Our findings indicate that at 300 g kg?1 dietary crude protein, a CHO : L ratio of 5.3 is recommended for piracanjuba, and the required energy is either 13.63 kJ g?1 if raised for aquaculture or 14.82 kJ g?1 if destined to stock enhancement.  相似文献   

20.
Four isonitrogenous diets containing different carbohydrate:lipid (CHO:L) ratios (0.3, 0.6, 1.1 and 1.8) were tested in triplicate groups (16 fish per replicate) of silvery‐black porgy juveniles for 8 weeks. Growth performance was not affected by different dietary CHO:L ratios (P > 0.05); however, the viscerosomatic index, the intraperitoneal fat, whole‐body lipid, energy and n‐3 long chain polyunsaturated fatty acids levels increased with decreasing dietary CHO:L ratios (P < 0.05). Fish fed with 1.8 CHO:L diet had the lowest apparent digestibility coefficients of protein and lipid, as well as the lowest plasma haemolytic and lysozyme activities (P < 0.05). Red blood cell counts and plasma glucose levels were higher in fish fed with 1.1 and 1.8 CHO:L ratio diets than in the other groups (P < 0.05). Plasma alkaline phosphatase and alanine aminotransferase, as well as the level of lipid peroxidation and total antioxidant capacity in the liver and plasma increased as dietary CHO:L ratios decreased (P < 0.05). The results of the current study indicated that the diets with CHO:L ratios between 0.6 and 1.1 are optimal for silvery‐black porgy, whereas higher ratios may result in hyperglycaemia and immune suppression, and lower CHO:L ratios may lead to oxidative stress and liver dysfunction.  相似文献   

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