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1.
A feeding trial was conducted to evaluate the effects of dietary magnesium on the growth, carapace strength, tissue and serum Mg concentration of soft‐shelled turtles, Pelodiscus sinensis (Wiegmann). Juvenile soft‐shelled turtles of approximate 5.4 g body weight were fed diets with seven levels of Mg (48, 206, 369, 670, 955, 1195 and 1500 mg Mg kg?1) for eight weeks. No significant difference (P ≥ 0.05) was found in weight gain (WG), feed conversion ratio or protein efficiency ratio among treatments. However, the WG of turtles continued to increase with increasing dietary Mg levels up to 670 mg kg?1, beyond which the WG levelled off. The plasma alkaline phosphatase activity and the muscle, bone Mg concentrations of the turtles increased with the increasing dietary Mg levels between 48 and 955 mg kg?1, beyond which the tissue Mg concentrations remained relatively constant. Furthermore, the carapace strengths of turtles fed with the control diet of 48 mg Mg kg?1 were significantly weaker (P < 0.05) than that of turtles fed with diets containing higher Mg levels. Based on a broken‐line modelling analysis, the required dietary Mg level for the optimal WG of juvenile soft‐shelled turtles was estimated to be approximately 650 mg kg?1. By contrast, the required dietary Mg levels for turtles to reach the optimal muscle and bone Mg concentrations were 1050 and 1000 mg kg?1 respectively. The required dietary Mg level for maximal alkaline phosphatase activity was approximately 980 mg kg?1.  相似文献   

2.
A feeding trial was conducted to evaluate the dietary vitamin A requirement of the soft‐shelled turtle Pelodiscus sinensis. Turtles with an approximate body weight of 6.8 g were fed diets containing 0–4.58 mg kg?1 (15 251 IU) vitamin A (retinyl acetate) for 8 weeks. Turtles fed diets without vitamin A showed the lowest growth performance. The animals gradually gained weight when dietary vitamin A increased from 0 to 3.6 mg kg?1. Liver vitamin A gradually increased with supplementation of dietary vitamin A of up to 2.7 mg kg?1. Beyond this concentration, the vitamin A in the liver significantly increased. Data analysis using a polynomial regression or exponential model showed that the estimated dietary vitamin A requirement for juvenile soft‐shelled turtles based on weight gain, red blood cell count and liver vitamin A measurements was 3.48, 2.84 and 2.58 mg kg?1, respectively.  相似文献   

3.
A 10‐week feeding trial was conducted to evaluate the effects of dietary zinc (Zn) contents on the growth, tissue trace element contents and serum Zn levels in soft‐shelled turtles, Pelodiscus sinensis. Juvenile soft‐shelled turtles approximately 4.8 g in body weight were fed casein‐based diets containing seven levels of Zn (14, 23, 32, 43, 58, 87 and 100 mg kg?1) for 10 weeks. There were no significant differences (P > 0.05) in weight gain (WG), feed conversion ratio (FCR) or protein efficiency ratio (PER) among the dietary treatments. However, Zn concentrations in the liver, serum and carapace of turtles fed the basal diet containing 14 mg Zn kg?1 were the lowest among all groups. Zn contents in the liver, serum and carapace increased when dietary Zn increased up to a dietary Zn level of approximately 43 mg kg?1. Beyond this dietary level, tissue Zn contents were relatively constant. Carapace iron (Fe), selenium (Se) in hard tissues and haemoglobin concentrations decreased when dietary Zn increased. Dietary Zn requirements of juvenile soft‐shelled turtles derived from regression modelling using the liver, serum, carapace and bone Zn contents as indicators were 42, 39, 35 and 46 mg Zn kg?1, respectively.  相似文献   

4.
A feeding trial was conducted to evaluate the effect of dietary β‐carotene level on the growth and liver vitamin A concentrations in soft‐shelled turtles, Pelodiscus sinensis, fed a vitamin A‐free diet. Soft‐shelled turtles were fed diets containing 0, 14.5, 26.5, 47.5, 87.3, 112.8 and 163.8 mg β‐carotene kg?1 for 10 weeks. Although it was not statistically significant due to high deviation within each group, mean weight gain of soft‐shelled turtles fed the diet without β‐carotene supplementation was the lowest among all test groups. Vitamin A concentrations in liver of turtles significantly (P<0.05) increased when dietary β‐carotene level reached 47.5 mg kg?1 indicating that soft‐shelled turtles were capable of converting β‐carotene to vitamin A. Analysed by regression modelling, dietary β‐carotene levels for optimal growth and maximal liver vitamin A contents of juvenile soft‐shelled turtles fed the vitamin A‐free diets were 49.1 and 88.7 mg kg?1 respectively.  相似文献   

5.
A feeding trial was conducted to determine the effect of dietary vitamin E supplementation on growth, liver lipid peroxidation and liver and muscle vitamin E level of soft‐shelled turtle, Pelodiscus sinensis. Eight experimental diets analysed to contain 0–457 IU vitamin E kg?1 were fed to juvenile soft‐shelled turtle of 4.8 g initial body weight for 12 weeks. Weight gain (WG) of the turtles fed the diet containing no vitamin E was significantly lower than those fed diets containing 83–457 IU vitamin E kg?1 (P<0.05). Feed conversion ratio and protein efficiency ratio showed similar trends to that of WG. No significant difference (P>0.05) was found in whole‐body composition among turtles fed the different diets. Dietary vitamin E requirement using WG as the response and estimated using the broken‐line regression model is approximately 88 IU kg?1. Liver and muscle vitamin E content increased when dietary vitamin E level increased. Ascorbate‐induced lipid peroxidation in liver tissue of turtles fed diets containing 0 and 17 IU vitamin E kg?1 was significantly (P<0.05) greater than those fed diets containing high vitamin E (≥35 IU kg?1).  相似文献   

6.
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   

7.
This study investigated the effects of dietary niacin on growth performance, feed utilization and non‐specific immune response in juvenile Pacific white shrimp. Six isonitrogenous and isolipidic practical diets were formulated with graded niacin levels of 10.9, 65.8, 121.2, 203.4, 387.5 and 769.3 mg kg?1 of dry diet, respectively. Results indicated that per cent weight gain (WG), specific growth rate (SGR), feed efficiency (FE), protein efficiency ratio (PER) and protein productive value (PPV) were significantly influenced by the dietary niacin levels. The maximum WG and SGR occurred at 121.2 mg kg?1 niacin diet. However, survival and proximate composition of whole body were not significantly affected by the dietary niacin levels. Dietary niacin levels had no significant effects on the total protein, glucose, triacylglycerol and cholesterol contents in the haemolymph. The activity of catalase and lysozyme in the haemolymph was significantly affected by dietary niacin levels. Based on a two‐slope regression analysis of SGR against dietary niacin level, the dietary niacin requirement of juvenile Pacific white shrimp was 109.6 mg kg?1.  相似文献   

8.
A 12‐week feeding trial was conducted to evaluate the effects of dietary vitamin C on growth performance, antioxidant status and innate immune responses in juvenile yellow catfish, Pelteobagrus fulvidraco. Six isonitrogenous and isolipidic diets (44% crude protein and 7% lipid) were formulated to contain six graded dietary vitamin C (ascorbate‐2‐poly‐ phosphate, ROVIMIX® STAY‐C® 35) levels ranging from 1.9 to 316.0 mg kg?1 diet. The results of present study indicated that fish fed the lowest vitamin C diet had lower weight gain (WG) and specific growth rate (SGR) than those fed the diets supplemented vitamin C. WG and SGR did significantly increase with dietary vitamin C levels increasing from 1.9 to 156.5 mg kg?1. However, no significant increase was observed with further dietary vitamin C levels increasing from 156.5 to 316 mg kg?1. Survival, protein efficiency ratio and feed efficiency were not significantly affected by the dietary vitamin C levels. The activities of serum superoxide dismutase, catalase and glutathione peroxidase significantly increased when dietary vitamin C levels increased from 1.9 to 156.5 mg kg?1, fish fed the lowest vitamin C diet had higher serum malondialdehyde content than those fed the diets supplemented with vitamin C. Fish fed the diet containing 156.5 mg kg?1 vitamin C had the highest lysozyme, total complement activity, phagocytosis index and respiratory burst of head kidney among all treatments. The challenge test with Aeromonas hydrophila indicated that lower cumulative survival was observed in fish fed the lowest vitamin C diet. Analysis by broken‐line regression of SGR and lysozyme activity indicated that the dietary vitamin C requirement of juvenile yellow catfish was estimated to be 114.5 and 102.5 mg kg?1 diet, respectively.  相似文献   

9.
Two experiments were conducted to quantify the dietary thiamin (experiment I) and pyridoxine (experiment II) requirements of fingerling Cirrhinus mrigala for 16 weeks. In experiment I, dietary thiamin requirement was determined by feeding seven casein–gelatin‐based diets (400 g kg?1 CP; 18.69 kJ g?1 GE) with graded levels of thiamin (0, 0.5, 1, 2, 4, 8 and 16 mg kg?1 diet) to triplicate groups of fish (6.15 ± 0.37 cm; 1.89 ± 0.12 g). Fish fed diet with 2 mg kg?1 thiamin had highest specific growth rate (SGR), protein retention (PR), RNA/DNA ratio, haemoglobin (Hb), haematocrit (Hct), RBCs and best feed conversion ratio (FCR). However, highest liver thiamin concentration was recorded in fish fed 4 mg thiamin kg?1 diet. Broken‐line analysis of SGR, PR and liver thiamin concentrations exhibited the thiamin requirement in the range of 1.79–3.34 mg kg?1 diet (0.096–0.179 μg thiamin kJ?1 gross energy). In experiment II, six casein–gelatin‐based diets (400 g kg?1 CP; 18.69 kJ g?1 GE) containing graded levels of pyridoxine (0, 2, 4, 6, 8 and 10 mg kg?1 diet) were fed to triplicate groups of fish (6.35 ± 0.37 cm; 1.97 ± 0.12 g). Fish fed diet containing 6 mg kg?1 pyridoxine showed best SGR, FCR, PR, RNA/DNA ratio, Hb, Hct and RBCs, whereas maximum liver pyridoxine concentration was recorded in fish fed 8 mg kg?1 dietary pyridoxine. Broken‐line analysis of SGR, PR and liver pyridoxine concentrations reflected the pyridoxine requirement from 5.63 to 8.61 mg kg?1 diet. Data generated during this study would be useful in formulating thiamin‐ and pyridoxine‐balanced feeds for the intensive culture of this fish.  相似文献   

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

11.
Ethoxyquin (EQ) is the most common synthetic antioxidant used for preventing rancidity in fish foodstuffs. However, literature related to the effects of dietary EQ on performance of fish was limited. The present study was conducted to investigate the effects of EQ on performance and EQ residue in muscle of juvenile Japanese seabass Lateolabrax japonicus and to estimate the optimal EQ concentration in the diet. Graded levels [0 (control), 50, 150, 450 and 1350 mg EQ kg?1 diet] of EQ were added to the basal diet, resulting in five dietary treatments in the experiment. Each diet was fed to triplicate groups of seabass (initial body weight 8.01 ± 0.76 g) for 12 weeks in floating sea cages (1.5 × 1.5 × 2.0 m, 30 fish per cage). Survival ranged from 78.9 to 86.7%, and was irrespective of dietary EQ levels. The specific growth rate (SGR) of fish fed diets supplemented with ≤50 mg kg?1 EQ had significantly (P < 0.05) higher SGR than fish fed diets supplemented with ≥150 mg kg?1 EQ, the highest SGR was observed in fish fed diet with 50 mg kg?1 EQ supplementation. Feed intake (FI) and feed efficiency (FE) were not significantly (P > 0.05) different among dietary treatments. Fish fed diets with 50 and 1350 mg kg?1 EQ had a significant (P < 0.05) lower body lipid content than fish in the control group. Muscle EQ level significantly increased when dietary EQ increased. Optimal EQ concentration estimated by polynomial regression based on maximum growth of juvenile Japanese seabass was 13.78 mg kg?1 diet.  相似文献   

12.
Soft-shelled turtles, Pelodiscus sinensis , with an average weight of 5.55 g, were fed diets supplemented with eight levels of ferrous sulphate for 8 weeks. The analysed iron content ranged from 50.8 to 482.9 mg kg−1. Growth rate of turtles fed the control diet with no iron supplementation was the lowest among all dietary groups. Haematological parameters including red blood cell, haemoglobin, haematocrit, mean corpuscular volume, mean corpuscular haemoglobin and mean corpuscular haemoglobin concentration of the turtles fed the control diet were also significantly ( P  < 0.05) lower relative to the other groups. Thus, dietary iron at 50.8 mg kg−1 (no supplemented iron) was deemed deficient for growth and ineffective at preventing anaemia in juvenile soft-shelled turtle. Whereas, a supplementation of 50 mg kg−1 ferrous sulphate (a total dietary iron of 91.8 mg kg−1) was enough to normalize the haematological values of soft-shelled turtles to the level similar to other iron supplement-fed groups. Within the tested dietary iron range, liver iron content curve-linearly ( r 2 = 0.99) increased with increasing dietary iron level. Furthermore, thiobarbituric acid-reactive substances in liver tissues of the turtles have also increased when liver iron content increased. The dietary iron requirement of soft-shelled turtle is 120–198 mg kg−1 when ferrous sulphate is used as the source of iron.  相似文献   

13.
To assess the effects of dietary astaxanthin on the growth and body colour of red discus fish (Symphysodon spp.), synthetic astaxanthin was added into the basal diet (beef heart hamburger) with the levels of 0 (control diet), 50, 100, 200, 300 and 400 mg kg?1 respectively. The six experimental diets were fed to discus fish with an initial body weight of 10.3 ± 0.8 g for 8 weeks. The results showed that the supplementation of 50–200 mg kg?1 astaxanthin had no significant effects on growth performance of discus fish, but the high supplementation of astaxanthin (300 or 400 mg kg?1) significantly reduced the weight gain and increased the feed coefficient ratio (P < 0.05). After 4 or 8 weeks of feeding, the L* (lightness) values in astaxanthin‐supplemented groups were significantly lower, while a* (redness), b* (yellowness) and skin astaxanthin contents were significantly higher than the control group (P < 0.05). When the astaxanthin supplementation reached 200 mg kg?1, skin redness and astaxanthin contents remained relatively stable. When b* was relatively stable, the supplemental astaxanthin was 300 (4 weeks) and 50 mg kg?1 (8 weeks) respectively. With the supplemental astaxanthin increasing, the astaxanthin retention rate significantly decreased and hepatic total antioxidant capacity was strengthened. The dietary astaxanthin also significantly increased the reduced glutathione level (P < 0.05) when the astaxanthin inclusion was higher than 50 mg kg?1. The above results showed that dietary astaxanthin could effectively improve the skin pigmentation of red discus fish in 4 weeks and the supplementation level was suggested to be 200 mg kg?1.  相似文献   

14.
A 10‐week feeding trial was conducted to estimate the optimum dietary manganese requirement for juvenile cobia, Rachycentron canadum L. The basal diet was formulated to contain 501 g kg?1 crude protein from vitamin‐free casein, gelatin and fish protein concentrate. Manganese sulphate was added to the basal diet at 0 (control group), 6, 12, 18, 24 and 36 mg Mn kg?1 diet providing 5.98, 7.23, 16.05, 23.87, 28.87 and 41.29 mg Mn kg?1 diet, respectively. Each diet was randomly fed to three replicate groups of cobia for 10 weeks, and each tank was stocked with 30 fish (initial weight, 6.27 ± 0.03 g). The manganese concentration in rearing water was monitored during the feeding period and was < 0.01 mg L?1. Dietary manganese level significantly influenced survival ratio (SR), specific growth ratio (SGR), feed efficiency ratio (FER) and the manganese concentrations in the whole body, vertebra and liver of cobia. When the dietary manganese level rose from 5.98 mg kg?1 to 23.87 mg kg?1, the superoxide dismutase (SOD; EC 1.15.1.1) activities in liver also increased (P < 0.05). But there was no significant change in SOD activities for the groups fed with diets containing manganese level higher than 23.87 mg kg?1. On the basis of broken‐line regression of SGR, manganese concentration in whole body and vertebra the manganese requirements of juvenile cobia were 21.72 mg kg?1, 22.38 mg kg?1 and 24.93 mg kg?1 diet in the form of manganese sulphate, respectively.  相似文献   

15.
This study was conducted to determine dietary thiamine requirement of juvenile Sclizothorax prenanti and evaluate the effect of dietary thiamine levels on growth performance, body composition and haemato‐biochemical parameters for this fish species. The seven experimental diets were formulated to contain the graded levels of thiamine (0, 10, 20, 30, 40, 60 and 100 mg kg?1 diet, respectively), providing the actual dietary thiamine values of 0.31 (control), 9.82, 21.49, 29.83, 41.66, 62.24 and 114.58 mg kg?1 diet, respectively. Each diet was assigned to three replicate groups of S. prenanti (initial body weight: 13.46 ± 0.28 g, means ± SD) for 60 days. Increasing dietary thiamine level up to 21.49 mg kg?1 diet increased weight gain rate (WGR), specific growth rate (SGR), feed efficiency (FE) and protein efficiency ratio (PER) (P < 0.05), beyond which they remained nearly unchanged. Similarly, hepatic thiamine concentration and several serum biochemical parameters (transketolase activity, triglyceride and total cholesterol contents) increased with increasing levels of thiamine up to 21.49 mg kg?1 diet (P < 0.05) and, thereafter, remained almost constant. However, no significant differences in body composition (moisture, protein, lipid and ash contents) were found among dietary thiamine treatments (P > 0.05). Analysis by the broken‐line regression of WGR, SGR, FE, PER, hepatic thiamine concentration and serum transketolase activity indicated that dietary thiamine requirements in juvenile S. prenanti were 18.45–25.91 mg kg?1 diet.  相似文献   

16.
A 10‐week feeding trial was conducted to estimate the dietary vitamin K requirements of juvenile Chinese soft‐shelled turtles, Pelodiscus sinensis, using menadione sodium bisulphite (MSB) as the vitamin K source. Juvenile soft‐shelled turtles with 6.1 ± 0.1 g body weight were individually reared and fed diets containing seven levels of MSB (0.0, 5.0, 8.9, 12.3, 16.6, 20.7 and 41.0 mg/kg). Turtles fed with an MSB‐free diet exhibited the lowest feed utilization, carapace Ca concentrations, carapace strength or liver menaquinone (MK‐4) concentrations among all dietary groups. Weight gain (WG) in the turtles tended to increase with increase in dietary MSB until a dietary MSB level of 16.6 mg/kg, where WG levelled off. Total plasma prothrombin concentrations, an indicator for blood clotting function, in the turtles fed on MSB supplemented diets were significantly (p < 0.05) lower than those in turtles fed on MSB supplemented diets. Liver MSB concentrations increased with increase in dietary MSB. Using broken‐line or sigmoidal regression model, the vitamin K requirements of juvenile Chinese soft‐shelled turtles based on WG, total plasma prothrombin concentrations and liver vitamin K were 21.5, 25.8 and 29.9 mg MSB per kg, respectively.  相似文献   

17.
The study was conducted to determine the effect of dietary supplementation of vitamin C on anti‐acid stress ability in juvenile soft‐shelled turtle. The soft‐shelled turtles were fed vitamin C supplemented diets at levels of 0, 250, 500, 2500, 5000 and 10 000 mg kg?1 for 4 weeks. The results showed that the phagocytic rate of blood cell in the group fed vitamin C deficient diets, the serum bacteriolytic activity in the two groups fed vitamin C supplemented diet at 0 and 250 mg kg?1 and the serum bactericidal activity in all groups after acid stress significantly decreased compared with those of before stress (P < 0.1). The phagocytic rate of blood cells in the two groups fed vitamin C supplemented diet at 2500 and 5000 mg kg?1 were significantly higher than those of the four groups fed at 0, 250, 500 and 10 000 mg kg?1 (P < 0.01). The serum bacteriolytic activity in the groups fed vitamin C supplemented diet at 500, 2500, 5000 and 10 000 mg kg?1 were significantly higher than that of the group fed vitamin C deficient diets (P < 0.05), and the two groups fed vitamin C at 2500 and 5000 mg kg?1 were significantly higher than those of the groups fed at 250 and 10 000 mg kg?1 (P < 0.05). The serum bactericidal activities in the four groups fed vitamin C supplemented diet at 500, 2500, 5000 and 10 000 mg kg?1 were significantly higher than those of the two groups fed at 0 and 250 mg kg?1 diet (P < 0.01), and the two groups fed vitamin C at 2500 and 5000 mg kg?1 were significantly higher than those of the two groups fed at 500 and 10 000 mg kg?1 (P < 0.1). These results suggest that supplementation of vitamin C higher than 250 mg kg?1 is necessary to reduce the adverse effects of acid stress.  相似文献   

18.
A 75 days experiment was conducted in a flow‐through system on juvenile gibel carp (Carassius auratus gibelio) (3.43 ± 0.01 g) to evaluate the effects of dietary lysozyme on growth performance, intestine morphology, microbiota and immune response. Four isonitrogenous (crude protein: 367 g kg?1) isolipid (62 g kg?1) and isocaloric (gross energy: 17.92 kJ g?1) diets were formulated to contain 0, 100, 500 and 1000 mg kg?1 lysozyme, respectively. The results showed that specific growth rate (SGR) and feed efficiency (FE) increased at 1000 mg kg?1 lysozyme. Blood leucocyte phagocytic activity (PA) and serum lysozyme (LZM) decreased with dietary lysozyme on day 25, 50 and 75. There were no significant differences in alternative complement pathway (ACP), respiratory burst (ROS), serum superoxide dismutase (SOD), glutathione peroxidase (GSHpx) or malonaldehyde (MDA). After Aeromonas hydrophilia challenge, higher survival was obtained at 500 mg kg?1 group. PA, ROS, SOD, LZM and ACP increased with increasing dietary lysozyme, while MDA reversed. Goblet cells in mid‐intestine and microvilli height in distal intestine increased with dietary lysozyme on day 75. Dietary lysozyme reduced the diversity of intestine microbiota. In conclusion, oral administration of 500 mg kg?1 dietary lysozyme for 75 days is recommended for the survival of gibel carp and 1000 mg kg?1 dietary lysozyme for fast growth.  相似文献   

19.
A 9‐week feeding trial was conducted to investigate the dietary methionine requirement of juvenile Megalobrama amblycephala at a constant dietary cystine level. Six semipurified diets were formulated to contain graded dietary methionine levels from 3.9 to 15.4 g kg?1 in about 2.5 g kg?1 increments in the presence of 2.2 g kg?1 cystine. Results showed that specific growth rate (SGR) and protein efficiency ratio (PER) significantly increased with increasing dietary methionine levels from 3.9 to 12.4 g kg?1 and thereafter kept stable. Maximum protein productive value (PPV), nitrogen retention efficiency (NRE) and liver weight were observed in 8.5 g methionine kg?1 diet. Protein contents in whole fish body were positively correlated with dietary methionine level, while lipid contents were negatively correlated with it. Morphological index and hepatic glutamate‐pyruvate transaminase (GPT) activities were independent of dietary methionine levels. However, dietary methionine supplementation significantly improved haematological parameters, plasma methionine and total essential amino acid contents and hepatic glutamate‐oxaloacetate transaminase (GOT) activities. Analysis of dose response using broken‐line regression on the basis of SGR and PPV versus dietary methionine level estimated the optimum dietary methionine requirements of juvenile M. amblycephala to be between 8.5 and 8.4 g kg?1 of diet (25.0 and 24.7 g kg?1 of protein) in the presence of 2.2 g kg?1 cystine, respectively. Hence, the corresponding total sulphur amino acids requirements of this species were calculated to be 10.7 and 10.6 g kg?1 of diet (31.5 and 31.2 g kg?1 of dietary protein).  相似文献   

20.
A growth experiment was conducted to determine the effect of supplementing dietary calcium in fish meal‐based diets on the growth of cultured soft‐shelled turtle Pelodiscus sinensis. Juvenile soft‐shelled turtles of 4.1 g mean body weight were fed nine diets containing two levels of phosphorus (2.7% or 3.0%) and analysed calcium levels ranging from 4.7% to 6.6% for 10 weeks. The growth of the turtles was enhanced when inorganic calcium was added to the diets. The weight gain of the turtles fed the control diet containing calcium solely from fish meal was the lowest among the test groups, and was significantly lower than those fed the diet containing 5.7% calcium at the 3.0% phosphorus level (P<0.05). Feed conversion and protein efficiency ratios were not affected by different dietary treatments. Whole‐body moisture and crude protein contents of turtles were not affected by different dietary treatments. The body ash of turtles fed 3.0% phosphorus diets tended to be higher than turtles fed 2.7% phosphorus diets. The body calcium to phosphorus ratio of turtles fed 3.0% phosphorus diets was greater than that of turtles fed diets containing 2.7% phosphorus. Supplementation of Ca in a fish meal‐based practical diet is required for the optimum growth of soft‐shelled turtles.  相似文献   

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