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1.
Two experiments were performed to investigate the digestibility and utilization of carbohydrate sources by Australian snapper Pagrus auratus. In the first experiment, snapper of two different size classes (110 and 375 g) were fed a reference diet containing no starch (REF) or diets containing 150 (PN15), 250 (PN25), 350 (PN35) or 450 g kg?1 (PN45) of 100% gelatinized wheat starch to investigate the interactive effects of fish size and starch inclusion level on apparent organic matter (OM) or gross energy (GE) digestibility (ADC), post‐prandial plasma glucose concentration, hepatosomatic index (HSI) and liver or tissue glycogen content. A second experiment used a 72 h time course study to investigate the ability of larger snapper (300–481 g) to clear an intra‐peritoneal injection of 1 g d ‐glucose kg?1 body weight (BW). Organic matter and GE ADCs declined significantly in both fish sizes as the level of starch increased (PN45energy small fishenergy large fish). There was no interaction between fish size and inclusion level with respect to GE or OM ADCs. Gross energy ADC for both sized fish was described by the linear function GE ADC=104.97 (±3.39)–0.109 (±0.010) × inclusion level (R2=0.86). Hepatosomatic index, liver and muscle glycogen concentrations were significantly elevated in both small and large snapper‐fed diets containing gelatinized starch compared with snapper fed the REF diet. Three‐hour post‐prandial plasma glucose concentrations were not significantly affected by fish size, inclusion level or the interaction of these factors (REF=PN15=PN25=PN35=PN45), and ranged between 1.60 and 2.5 mM. The mean±SD resting level of plasma glucose (0 h) was 2.4±1.1 mM. Circulating levels of plasma glucose in snapper peaked at 18.9 mM approximately 3 h after intra‐peritoneal injection and fish exhibited hyperglycaemia for at least 12–18 h. There were no significant differences between the plasma glucose concentrations of snapper sampled 0, 18, 24, 48 or 72 h after injection (0=18=24=48=72<12< 1<3=6 h), indicating snapper required almost 18 h to regulate their circulating levels of glucose to near‐basal concentrations. Australian snapper are capable of digesting moderate levels of gelatinized wheat starch; however, increasing the dietary content of starch resulted in a reduction in OM and GE digestibility. Smaller snapper appear to be less capable of digesting gelatinized starch than larger fish, and levels above 250 and 350 g kg?1 of diet are not recommended for small and large fish respectively. Snapper subjected to an intra‐peritoneal injection of d ‐glucose have prolonged hyperglycaemia; however, the post‐prandial response to the uptake of glucose from normally digested gelatinized starch appears to be more regulated.  相似文献   

2.
The effect of the different dietary carbohydrate types and levels on growth performance, haematological indices and hepatic hexokinase (HK) and glucokinase (GK) genes expression involved in control of glucose metabolism, was studied in juvenile mirror carp (Cyprinus carpio). Two carbohydrates (glucose and starch) diets with two levels (250 and 500 g kg?1) were fed to triplicate groups of 35 fish for 60 days. The best weight gain rate and specific growth rate were observed in fish fed with 250 g kg?1 glucose diet and 500 g kg?1 starch diet (P < 0.05). Fish fed with 500 g kg?1 glucose showed low feed utilization, with the highest food conversion ratio and the lowest protein efficiency ratio (P < 0.05). Hepatosomatic index was significantly higher in fish fed with glucose diets and the 500 g kg?1 starch diet compared to 250 g kg?1 starch. CHOL, HDL‐C and LDL‐C were significantly highest in fish fed with 500 g kg?1 starch than all other diets (P < 0.05). Hepatic GK mRNA expression level and activity were positively related to glucose and starch levels (P < 0.05). Correlation analysis showed that hepatic glycogen concentration was increased by dietary carbohydrate content (P < 0.05). These results suggest that GK may play a major role in the postprandial glucose utilization in juvenile mirror carp.  相似文献   

3.
Abstract Intraperitoneal carbohydrate tolerance tests were done to assess the ability of silver perch, Bidyanus bidyanus, to utilize the predominant monosaccharides in plant ingredients currently being used in the formulation of aquaculture feeds for this species. Preliminary experiments carried out to assess baseline plasma glucose concentrations indicated that blood glucose levels were elevated within 2 min of handling and silver perch required a period of 48 h without feeding before plasma glucose levels remained constant. In the first carbohydrate test, either glucose, galactose or xylose were administered by injection into the intraperitoneal cavity at a dose rate of 1 g carbohydrate kg?1 body weight (BW). In the second carbohydrate test, glucose was administered at a dose rate of either 2 or 4 g glucose kg BW?1. Following injection, uptake and clearance rate of the carbohydrates from the blood stream was monitored over a 24‐h period. Silver perch were significantly more efficient at the uptake and clearance of glucose from the blood stream than xylose or galactose. Maximum plasma glucose concentrations (22.2 mmol L ?1) were recorded at 1 h following injection and basal levels (3.44 mm ) were attained between 6 and 12 h following injection. For both galactose and xylose, maximum concentrations were recorded at 1 and 3 h, respectively, and concentrations of both monosaccharides remained significantly elevated 24 h after the administration. Plasma glucose concentrations of silver perch administered with either 2 or 4 g glucose kg BW?1 were significantly elevated and peaked at similar levels (30.2 mmol L ?1 and 30.7 mmol L ?1 respectively) 3 h after injection. Basal plasma glucose concentrations were attained in silver perch injected with 2 g glucose kg BW?1 at 24 h following administration. Plasma glucose concentrations remained significantly elevated in fish injected with 4 g glucose kg BW?1 after 24 h. These findings indicate that silver perch are more efficient at utilizing glucose than either xylose or galactose, and that there are also differing maximum threshold for the inclusion of ingredients rich in glucose, galactose and xylose into the diets of silver perch.  相似文献   

4.
A 60‐day experiment was carried out to investigate dietary starch levels on growth performance, hepatic glucose metabolism and liver histology of largemouth bass, Micropterus salmoides. Fish (initial weight 22.00 ± 0.02 g) were fed five graded levels of dietary corn starch (0, 50, 100, 150 and 200 g/kg). Fish fed low (0 and 50 g/kg) dietary starch showed significantly higher weight gain than other groups (p < .05). Liver lipid and glycogen accumulations were induced when dietary starch higher than 100 g/kg. After 20 days of feeding, hexokinase activity and mRNA expression were decreased in fish fed dietary starch higher than 150 g/kg (p < .05) and the pyruvate kinase showed the opposite tendency. Insulin receptor 1 (irs1), glucagon‐like peptide‐1 receptor and glucose transport protein 2 (glut2) mRNA expression were decreased with the increasing dietary starch after 10 days of feeding (p < .05). These results indicated gluconeogenesis was depressed and β‐oxidation was enhanced in response to high dietary starch, while the glycolysis was inhibited and endocrine system was impaired when fish fed high dietary starch; then, glucose homeostasis was disturbed and finally led to the glucose intolerance of largemouth bass.  相似文献   

5.
Two experiments were conducted to ascertain the utilization of different carbohydrate sources and different forms of starch present in bagrid catfish (Mystus nemurus) fry. The nutritional quality and starch forms of cornstarch, dextrin, broken rice, and sago flour were evaluated in a 4 × 2 factorial design. All diets were formulated to be isonitrogenous (400 g kg?1 crude protein) and isolipidic (150 g kg?1 crude lipid), fed to triplicate groups of bagrid catfish fry (initial weight 6.04 ± 0.04 g). Growth studies, enzymatic response and postprandial plasma glucose were observed. A two‐way anova (P > 0.05) analysis of the data obtained showed that the final body weight, specific growth rate (SGR) and food conversion ratio (FCR) were significantly affected by carbohydrate source, but not significantly affected by starch form. Fish fed broken rice and corn starch had similar SGR and FCR compared to fish fed with dextrin and sago flour. The postprandial plasma glucose trend in fish fed with corn starch and broken rice showed a gradual increase while sago flour and dextrin‐fed fish peaked at 2 and 3 h, respectively. Lipogenic enzyme (G6PDH) activity were more pronounced than gluconeogenic enzyme (ME) in M. nemurus irrespective of carbohydrate source and starch form. Therefore, we suggest that raw broken rice and corn starch are suitable carbohydrate sources in the M. nemurus diet.  相似文献   

6.
A 56‐day growth trial was conducted to study the utilization of hydrolysed potato starch by juvenile Atlantic salmon Salmo salar L. using a restricted feeding regime. Two diets supplemented with either 15% or 30% hydrolysed potato starch and a control diet without carbohydrate supplementation were each fed to triplicate groups of salmon. Feeding rate varied from 1.4% to 2.0% of body weight per day, so that fish were fed similar amounts of protein and lipid. In spite of the restricted feeding used, no growth stimulation was measured as a consequence of the additional starch intake. No variation was found in protein utilization, measured as protein efficiency ratio values (PER), while feed utilization showed decreased values as starch intake increased. Plasma glucose concentrations did not vary as a consequence of increased starch intake when measured 24 h after feeding, indicating efficient regulation of plasma glucose. In fish fed the 30% starch, the plasma triacylglycerol concentration was significantly increased, which may point to de novo lipid synthesis from the high starch intake. No variation was found in plasma cholesterol or protein concentrations, or asparagine aminotransferase, alanine aminotransferase and lactate dehydrogenase activities. This shows that the fish health status and liver function were normal (no mortality was registered). Liver and muscle showed increased glycogen levels as a function of increased starch intake. The same diets were also fed to juvenile white sturgeon Acipencer transmontanus and hybrid tilapia Oreochromis niloticus×O. aureus. These results are presented separately.  相似文献   

7.
A growth trial was conducted to feed juvenile tilapia (initial weight, 9.1±0.1 g), Oreochromis niloticus×O. aureus, isonitrogenous diets for 8 weeks. Six diets were formulated containing 29% crude protein from casein and gelatin, 10% crude fat from soybean oil and refined soybean lecithin and varying levels of corn starch ranging from 6% to 46% at increments of 8%, with corresponding energy to protein (E/P) ratios of 35.6, 37.9, 40.2, 42.5, 44.8 and 47.1 kJ g?1. Weight gain (WG), specific growth rate, feed efficiency ratio and protein efficiency ratio were significantly higher in fish fed diets with starch ≥22% (or E/P ratio ≥40.2 kJ g?1) than in fish fed diets with 6% or 14% starch (or E/P ratio of 35.6 or 37.9 kJ g?1). No further improvement was measured when dietary starch content increased beyond 22%. Body protein retention showed the same general pattern as WG, and was highest in fish fed the 22% starch diet. Body composition was significantly affected by dietary starch level. Fish fed diets with starch ≥30% had significantly higher lipid content than fish fed diets with 6% or 14% starch. Ash content was negatively correlated with starch inclusion level, but moisture and protein contents did not show discernible trends among treatments. Results indicate that hybrid tilapia can utilize 46% dietary starch without growth retardation, while 22% starch in feed for juvenile tilapia containing 29% protein and 10% lipid, or an E/P ratio of 37.9 kJ g?1 is optimal.  相似文献   

8.
The influence of two carbohydrates, starch and glucose, on hepatic enzyme activities of juvenile tilapia,Oreochromis niloticus xO. aureus, were investigated. Fish were fed either starch or glucose diet solely for 12 weeks or fed either starch or glucose diet for the first 6 weeks and then switched the diet each other for the last 6 weeks. Fish fed only the starch diet gained more (p < 0.05) body weight, had better feed conversion, higher protein deposition and energy retention values than fish fed the glucose diet. These parameters generally decreased in fish when the starch diet was fed first and then switched to the glucose diet, or increased in fish when the glucose diet was fed first and then switched to the starch diet. The starch — fed fish had higher body lipid content than glucose — fed fish. Body lipid decreased in fish transferred from the starch to glucose diet orvice versa when fish were transformed from the glucose to the starch diet. Hepatic hexokinase, phosphofructokinase, and glucose-6-phosphatase activities in fish were not affected by the different dietary regimes. Malic enzyme (ME), glucose-6-phosphate dehydrogenase (G-6-PD) and phosphogluconate dehydrogenase (PGD) activities were higher in the fish fed the starch diet than in those fed the glucose diet. Changing the diet from starch to glucose decreased ME, G-6-PD and PGD activities, whereas, changing the diet from the glucose to the starch increased these enzyme activities in fish liver. These results suggest that lipogenic enzyme activity can adapt to dietary carbohydrates in the fish liver.  相似文献   

9.
研究注射葡萄糖对吉富罗非鱼(Oreochromis miloticus)生化指标、胰岛素和糖酵解酶的影响。选取体质量约80 g的吉富罗非鱼150尾,随机分为2个实验组,对照组腹腔注射0.7%的无菌生理盐水,处理组按照30 mg/100 g(体质量)的剂量腹腔注射葡萄糖。结果表明:(1)吉富罗非鱼在注射葡萄糖后1 h血糖达到最高水平,而后显著下降(P<0.05),3 h后降低到正常水平。注射葡萄糖可显著提高胆固醇的含量(P<0.05),并显著降低谷草转氨酶水平(P<0.05),但对血浆蛋白、甘油三酯和谷丙转氨酶水平没有显著影响(P>0.05)。(2)肝糖原在葡萄糖注射后的6 h达到最高水平,而后显著下降(P<0.05),肌糖原没有发生变化。(3)血浆和肌肉中的胰岛素均在葡萄糖注射后的3 h达到最高水平,而后显著下降(P<0.05),而肝中的胰岛素水平没有发生变化。(4)丙酮酸激酶的活力在葡萄糖注射后6h达到最高水平(P<0.05),己糖激酶的活力在注射葡萄糖后没有发生变化。结果表明,注射葡萄糖可显著提高吉富罗非鱼血糖水平,且维持时间较长,胰岛素含量和丙酮酸激酶(PK)活力的提高均相对延迟,而己糖激酶活力的不足又限制了葡萄糖的酵解反应,从而引起血浆胆固醇升高,并伴有持续的血糖和肝糖原升高,从而产生营养胁迫的生理反应,加重鱼类对葡萄糖的代谢负担。  相似文献   

10.
Glucose tolerance in turbot, Scophthalmus maximus (L.)   总被引：1，自引：0，他引：1  
Eighty turbot, Scophthalmus maximus (L.), (average weight 61 g) were injected intraperitoneally with exactly 1 g glucose per kg body weight. There was a peak in plasma glucose 3 h post injection. Thereafter a gradual decrease to basal levels was seen within 24 h. Plasma triacylglycerol concentrations showed a rapid decline during the first 24 h, and thereafter stable values. Blood haematocrit values decreased from 20% before injection to 16% 72 h after injection. Liver glycogen concentrations showed an initial decrease from 8 to 5 g 100 g?1 (w.w) during the first 12 h, and thereafter stable values, while muscle glycogen concentrations increased during the first 12 h, and thereafter showed a gradual decline until 72 h. This response was most probably caused by secondary changes upon handling in combination with the direct response to a glucose load. Thus turbot was able to restore alterations in carbohydrate metabolism efficiently within 24 h.  相似文献   

11.
Nile tilapia were immunized by injecting extracellular products (ECP) of Mycobacterium spp. (strain TB40, TB267 or the type strain Mycobacterium marinum) into their swim bladders. A variety of adjuvants – Freund's complete adjuvant (FCA), Freund's incomplete adjuvant (FIA) and Titremax – were similarly injected into additional groups of tilapia. Phosphate-buffered saline (PBS) was used as a control. The number of nitroblue tetrazolium (NBT)-positive cells observed in the swim bladder of the immunized fish had significantly increased by the fourth day post-immunization. By day 8, the number of NBT-positive cells in fish immunized with ECP from mycobacteria strains TB40 or TB267 were fewer than in fish immunized with ECP from M. marinum or fish injected with FCA or FIA. The level of lysozyme activity detected in the serum of fish 4 days after being immunized with ECP from various Mycobacterium spp. was also significantly higher than that found in the serum of the control fish. Head kidney macrophages showed an enhanced reduction of NBT when cultured in vitro with 1 μg ml–1 of ECP. Concentrations greater than this (10 or 100 μg ml–1) were found to suppress the reduction of NBT by the macrophages.  相似文献   

12.
Stress has a considerable impact on welfare and productivity of fish, and blood glucose level of fish may be a factor modulating stress response. This study evaluated the effect of blood glucose level and handling on acute stress response of grass carp Ctenopharyngodon idella. Fish were intraperitoneally injected with glucose at 0, 0.2, 0.5, and 1.0 mg g?1 body mass (BM) and then were exposed to handling for 5 min. Glucose injection resulted in increase of plasma glucose level and liver glycogen content and decrease of plasma lactate level. Handling resulted in increase of plasma levels of cortisol, glucose, and lactate and plasma lactic dehydrogenase (LDH) activity and decrease of liver glycogen content. At 1 h post-stress, the plasma cortisol level was lower in the stressed fish injected with glucose at 0.5 mg g?1 BM than the stressed fish injected with glucose at 0, 0.2, and 1.0 mg g?1 BM. No significant differences were found in the activities of phosphoenolpyruvate carboxykinase (PEPCK) and pyruvate kinase (PK) in the liver between the stressed and unstressed fish, regardless of the dose of glucose injection. At 1 h post-stress, the liver glucose-6-phosphatase (G6Pase) activity was higher in the fish without glucose injection than in the fish injected with glucose. This study reveals that blood glucose level can affect stress response of grass carp by modulating cortisol release and glucose homeostasis through glycogen metabolism and gluconeogenesis in the liver.  相似文献   

13.
为研究饲料中添加3种不同的碳水化合物对大黄鱼生长性能、饲料利用以及糖代谢关键酶活性的影响,进行为期8周的生长实验和持续24 h的饥饿实验。以葡萄糖、小麦淀粉和糊精这3种碳水化合物作为糖源,设计3组等氮等脂(48%粗蛋白和12%粗脂肪)的饲料。选用初始体质量为(8.51±0.02)g的大黄鱼450尾,随机分为3组(每组3个重复,每个重复50尾)。养殖实验结束后进行饥饿实验,分别在饥饿实验开始后的0、1、3、5、7、9、11和24 h取样。结果显示,小麦淀粉组和糊精组大黄鱼的增重率和特定生长率显著高于葡萄糖组,且这2个饲料组的饲料系数显著低于葡萄糖组。糊精组大黄鱼的肝体比显著高于其余2组大黄鱼的肝体比。饲料中添加3种不同碳水化合物对大黄鱼成活率、脏体比和肥满度无显著性影响。葡萄糖组和小麦淀粉组大黄鱼血糖含量在饥饿1 h后都开始显著上升,葡萄糖组高血糖水平持续至少10 h;小麦淀粉组3 h显著下降至初始水平左右,未达到高血糖水平;糊精组大黄鱼血糖含量随着时间的推移持续升高,在11 h达到最大值,高血糖水平持续4 h。饲料中添加3种不同碳水化合物对大黄鱼血清胰岛素和肝糖原含量有显著性影响。小麦淀粉对大黄鱼肝脏葡萄糖激酶(GK)活性的升高有诱导作用。大黄鱼摄食3种不同碳水化合物饲料后鱼体血糖水平升高,但糖异生关键酶如葡萄糖-6-磷酸酶(G6Pase)、果糖-1,6-二磷酸酶(FBPase)和磷酸烯醇式丙酮酸羧激酶(PEPCK)的活性并不降低。饲料中添加葡萄糖和小麦淀粉对大黄鱼肝脏丙酮酸激酶(PK)活性有显著性影响。研究表明,大黄鱼利用结构复杂的多糖(如小麦淀粉和糊精)的能力要高于单糖(如葡萄糖),3种不同碳水化合物对大黄鱼血糖调节及糖酵解和糖异生途径关键酶活性的影响存在差异。  相似文献   

14.
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15.
The spotted wolffish (Anarhichas minor) is considered a promising species for coldwater aquaculture. It is a sedentary, bottom-dwelling fish which exhibits a calm and “non-stressed” behaviour in captivity. There are, however, no reports on the physiological responses to stressors in this species. In the present study we investigated primary (cortisol secretion) and secondary (glucose mobilization) responses to common aquaculture stressors like disturbance and hypoxia. Pre-stress plasma cortisol levels were within those generally considered representative for unstressed fish (~ 10 ng ml− 1), whereas basal glucose levels were unusually low (0.3–0.4 mM). After exposure to a short, but severe disturbance challenge (emptying the tank of water for 10 min), the increase in plasma cortisol level was slow and relatively weak, reaching a peak level of 25 ng ml− 1 4 to 8 h after disturbance. When the fish were exposed to a gradually decreasing oxygen level in the tank, a significantly elevated plasma cortisol level (35 ng ml− 1) was seen in the fish that remained in the tank until oxygen saturation had decreased to 20% oxygen saturation after 2.5 h. However, a two-fold higher plasma cortisol level (~ 70 ng ml− 1) was seen in all fish exposed to reduced oxygen levels (60, 40 and 20% oxygen saturation) after 3.5 h recovery in normoxic water. Plasma glucose levels showed only moderate increases (~ 70%) following disturbance and hypoxia challenges. An in vivo injection of ACTH caused a strong elevation of plasma cortisol (peak level ~ 170 ng ml− 1), demonstrating a high capacity for interrenal steroidogenesis in the spotted wolffish. The slow and relatively weak cortisol response to stressors, and low plasma glucose levels, may relate to the sedentary lifestyle of the spotted wolffish. The stress-response is characterised by a passive (reactive) coping style, which is considered adaptive for farming of this species.  相似文献   

16.
This study evaluated the total and differential leukocyte counting and the phagocytic activity in Nile tilapia Oreochromis niloticus experimentally injected with Enterococcus sp. in the swim bladder. Fish were distributed in four treatments in triplicates of non-injected fish, fish injected with 1 ml of sterile saline solution 0.65%, and fish injected with 1 × 103 and 1 × 106 colony-forming units (CFU) of Enterococcus diluted in 1 ml sterile saline. Twenty-four hours after injection, the fish were anesthetized and the blood collected for white blood cell (WBC) counts, differential counting of WBC, and phagocytic activity of blood leukocytes. The increased numbers of WBC and lymphocytes were followed by decreased number of monocyte after infection. The percentages of phagocytic activities in the blood were 55.3 and 55.9%, respectively, in tilapia injected with 1 × 103 and 1 × 106 CFU/ml.  相似文献   

17.
The concentrations of monoamines in the hypothalamus were determined in yellow perch Perca flavescens before and after injection with lipopolysaccharide (LPS; 3 mg kg−1 fish weight) or saline to test for the presence of neurochemical changes potentially associated with changes in plasma cortisol characteristic of intraperitoneal (ip) challenge with LPS. In the first experiment, yellow perch were injected with saline or LPS and the hypothalamus removed and plasma sampled before and at 0.5, 1.5, 3.0, and 6 h after injection. Plasma cortisol was elevated in both saline- and LPS-injected fish through 1.5 h after injection and returned to levels resembling pre-injection by 3 h after injection. Significantly higher amounts of cortisol in plasma from LPS-injected relative to saline-injected fish were observed 6 h following injection. A significant decrease relative to levels observed 0.5–3 h after handling was observed in serotonin concentrations at 6 h following LPS and saline injection with a concomitant increase in the ratio of 5-hydroxyindoleacetic acid:serotonin. In the second experiment, hypothalamic monoamines were sampled before and at 3, 6, 9, 12, and 24 h after injection with LPS or saline. Significant increases from pre-injection levels were observed in the ratio 5-hydroxyindoleacetic acid:serotonin at 9, 12, and 24 h after injection, but no differences were detected between LPS- and saline-injected fish. These results support a model linking serotonergic system activation following handling stress, but no correlations with the sustained elevations of plasma cortisol associated with inflammatory challenge were observed.  相似文献   

18.
Algamune? is a commercial additive produced from Euglena gracilis, providing a rich source of the β‐1,3‐glucan paramylon. Isolated kidney phagocytes of Nile tilapia were incubated with graded doses (0, 8, 16, 32, 64 and 128 μg/ml) of Algamune? and purified paramylon to gauge their ability to elicit the production of reactive oxygen species. A linear response was observed for extracellular superoxide anion for both sources but only Algamune? for intracellular superoxide anion. After corroborating the immunostimulant properties ex vivo, a feeding trial was conducted to evaluate the dietary supplementation of Algamune? (0, 100, 200, 400 and 800 mg/kg of diet) for Nile tilapia. Fish were fed for 3 weeks, after which, fish were sampled for blood and head kidney phagocytes. The remaining fish were challenged with Streptococcus iniae. Macrophage extracellular superoxide anion production was significantly elevated in fish fed diets with 200 mg of Algamune? kg?1 when compared to fish fed the basal diet. Even though the disease challenge did not show statistical differences, it is worth mentioning that fish fed intermediate doses of Algamune? had lowest numerical mortality values. Therefore, Algamune? was demonstrated to enhance some immunological responses of tilapia both in ex vivo and in vivo.  相似文献   

19.
A 8‐week feeding trial was conducted to determine the effect of substituting fish oil with palm oil‐laden spent bleaching clay (SBC), a by‐product from crude palm oil (CPO) refining, on growth, feed utilization, fatty acid composition and heavy metal accumulation in the muscle of Nile tilapia, Oreochromis niloticus. Four isonitrogenous and isolipidic practical diets were formulated to contain 0, 100, 200 or 300 g kg?1 SBC. Growth performance of Nile tilapia was significantly better in fish fed the 100 g kg?1 SBC diet compared with fish fed the 0, 200 or 300 g kg?1 SBC diet. Growth and feed utilization efficiency of fish fed 200 or 300 g kg?1 SBC were similar to fish fed the control diet without added SBC. Whole‐body composition, body‐organ indices and haematocrit of tilapia were not affected by dietary treatments. Fatty acid compositions in the muscle lipid of Nile tilapia were strongly influenced by dietary treatments with progressively elevated levels of total saturates and n‐6 PUFA because of the dietary influence of these fatty acids from residual CPO adsorbed onto SBC. A gradual decrease in total n‐3 PUFA concentrations were also observed with the ratio of n‐3 to n‐6 fatty acids in muscle lipids decreasing from 4.75 to 4.41, 3.23 or 2.37 after 8 weeks on the 0, 100, 200 or 300 g kg?1 SBC diet, respectively. The arsenic, cadmium and lead concentrations in the experimental diets increased with increasing dietary levels of SBC but the concentrations of these heavy metals in the whole body and bone of Nile tilapia were not significantly different among fish fed the various diets. The present 8‐week study showed that in fishmeal‐based diets for Nile tilapia, palm oil‐laden SBC can totally replace added fish oil. The use of this presently discarded waste product from palm oil refining in tilapia diets will greatly contribute to reducing the impact of rising feed costs in the culture of tilapia in many tropical countries. Other potential benefits may include acting as a feed binder, removal of mycotoxins in fish feeds as well as adsorbing toxic substances present in the culture water.  相似文献   

20.
This publication reports on analytical data from a large-scale experiment, using 3360 Atlantic salmon, Salmo salar L., distributed into 12 sea cages. Salmon were grown from an average 600 g to an average 3.5 kg. Samples for analyses were taken when fish were in the range of 1.8 and 3.5 kg. Dietary changes between groups were increased starch from 24 to 230 g kg?1 and balanced with protein. The diets were isolipic. All salmon showed small stores of glycogen in all analysed organs, and only in heart, gills and kidney of large fish (3.5 kg) were the levels correlated with dietary starch. Minor differences between groups were found in liver NADPH production, but with substantially decreased NADPH production per g protein as the fish grew from 1.8 to 3.5 kg, indicating that increasing dietary starch did not lead to induction of liver hexokinase, and that the activity of this enzyme may decline as fish size increases. An increase in plasma glucose concentrations was found as dietary starch increased, but all levels were moderate and ranged within reference values. Plasma total protein concentrations did not, however, vary according to decreased dietary protein, but increased substantially in all groups as the fish grew from 1.8 to 3.5 kg. Dietary treatments had no influence on haematological parameters, except for decreased haemoglobin concentrations as dietary starch increased in large fish (3.5 kg). No impared liver function was detected, evaluated by activities of ASAT, ALAT and LDH, and by histological analyses. Low serum lysozyme activities were recorded in all groups, and were not correlated with plasma glucose or liver glycogen concentrations.  相似文献   

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