scholarly journals The production of renal calcinosis by magnesium deficiency in rainbow trout (Salmo gairdneri)

1977 ◽  
Vol 38 (1) ◽  
pp. 127-135 ◽  
Author(s):  
C. B. Cowey ◽  
D. Knox ◽  
J. W. Adron ◽  
S. George ◽  
B. Pirie
Keyword(s):  
Rainbow Trout ◽  
Magnesium Deficiency ◽  
Light And Electron Microscopy ◽  
Extracellular Fluid ◽  
Renal Calculi ◽  
Salmo Gairdneri ◽  
List Type ◽  
Calcium Phosphorus ◽  
Dietary Treatments ◽  
Micro Analysis

1.Replicate groups of rainbow trout (Salmo gairdneri) were given one of five experimental diets (diets 1-5) for 16 weeks. The diets contained different amounts of calcium, phosphorus and magnesium and were prepared so that there were three levels of Ca (g/kg): 14 (diet 1), 26 (diets 2 and 3) and 40 (diets 4 and 5), Ca:P being approximately 1:1 in all diets. Diets 1, 2 and 4 had basal Mg levels (not more than 0.063 g/kg) whereas diets 3 and 5 contained supplementary Mg (1.0 g/kg).2.Weight gains of the trout given diets containing supplementary Mg were twice those of trout given diets with basal levels of Mg. At both dietary Mg concentrations weight gain was unaffected by the dietary Ca level.3.Serum Mg levels were significantly reduced in those trout given diets without supplementary Mg. The serum Ca level in those trout given the lowest concentration of Ca in their diet (14 g/kg, diet 1) was significantly greater than in those given higher amounts of Ca in their diets. Serum P levels were not significantly different with any of the experimental diets.4.The renal Ca concentration was increased in trout given diet 3 (26 g Ca/kg; basal Mg levels). No further increase in renal Ca concentration occurred in trout given diet 5 (40 g Ca/kg; basal Mg levels). With diets containing supplementary Mg renal Ca levels were increased at a dietary Ca level of 40 g/kg but not at a dietary Ca level of 26 g/kg. Renal Mg and P concentrations were not significantly different between any of the dietary treatments.5.Renal calculi were demonstrated by light and electron microscopy in tubules of those trout given diets 3 and 5 (basal Mg; 26 and 40 g Ca/kg respectively). Electron-probe micro-analysis showed that these calculi contained or comprised tricalcium phosphate.6.The skeletal muscle of Mg-deficient trout contained significantly more sodium than that of normal trout. It is suggested that this is indicative of an increase in extracellular fluid in the muscle of Mg-deficient trout.

scholarly journals Studies on the nutrition of salmonid fish. The magnesium requirement of rainbow trout (Salmo gairdneri)

1981 ◽  
Vol 45 (1) ◽  
pp. 137-148 ◽  
Author(s):  
D. Knox ◽  
C. B. Cowey ◽  
J. W. Adron
Keyword(s):  
Rainbow Trout ◽  
Weight Gain ◽  
Extracellular Fluid ◽  
Salmo Gairdneri ◽  
Initial Weight ◽  
Muscle Water ◽  
Low Levels ◽  
K Concentration ◽  
Dry Diet ◽  
Dietary Treatments

1. Rainbow trout (Salmo gairdneri) of mean initial weight 35 g were given one of five experimental diets for 20 weeks. The diets contained (g/kg dry diet) 15 calcium, 10 phosphorus and graded levels of magnesium from 0.04 (diet no. 1) to 1.0 (diet no. 5). In a second experiment rainbow trout of mean initial weight 16 g were given one of six experimental diets for 20 weeks. The diets contained (g/kg dry diet): Ca (40), P (30) and levels of Mg from 0.06 (diet no. 6) to 2.0 (diet no. 11).2. In both experiments weight gains were lowest in those trout given diets containing the basal levels of Mg (diet no. 1 and diet no. 6) but increased with increasing dietary Mg concentration. In neither experiment was there any further increase in weight gain once the Mg concentration reached 0.25–0.5 g/kg dry diet; weight gain reached a plateau at this dietary Mg level.3. The following trends occurred in serum electrolyte concentrations as dietary Mg increased. Mg increased in both experiments, in Expt 2 it reached a maximum of 1 mmol/l when the diet containted 0.5 g Mg/kg and did not increase further; sodium was positively correlated in both experiments; potassium decreased and in Expt 2 reached a plateau minimum of 1.7 mmol/l at a dietary Mg concentration of 0.5 g/kg; Ca and P altered little in either experiment.4. In both experiments renal Ca concentrations were greatly increased in trout given diets lacking supplementary Mg; they fell to low levels (3–5 mmol/kg) when diets conained 0.15 g Mg/kg or more. Renal K and P concentrations were negatively correlated with dietary Mg in Expt 2; other electrolytes measured were not altered in concentration by the treatments used.5. Extracellular fluid volume (ECFV) of muscle was negatively correlated with dietary Mg. In Expt 2 it reached a minimal or normal value at 0.5 g Mg/kg diet and did not decease further. Muscle Mg concentration increased with diet Mg in both experiments and muscle K concentration was also correlated with diet Mg in Expt 2. These changes were related to the shift in muscle water. In Expt 1, P concentration was decreased with increasing diet Mg but in Expt 2 its concentration increased, these changes may have been connected with the three-fold difference in dietary P in the two experiments.6. By contrast with skeletal muscle, Mg levels in cardiac muscle increased at low dietary Mg intakes.7. Concentrations of electrolytes in liver did not alter with dietary treatments used.8. The results show that Mg requirement of rainbow trout is met by a diet containing 0.5 g Mg/kg diet.

Use of Synthetic Diets and Biochemical Criteria in the Assessment of Nutrient Requirements of Fish

1976 ◽  
Vol 33 (4) ◽  
pp. 1040-1045 ◽  
Author(s):  
C. B. Cowey
Keyword(s):  
Fatty Acids ◽  
Rainbow Trout ◽  
Magnesium Deficiency ◽  
Scophthalmus Maximus ◽  
Salmo Gairdneri ◽  
Response Curves ◽  
Dietary Magnesium ◽  
Carbon Acids ◽  
Acid Status ◽  
Turbot Scophthalmus Maximus

Dietary allowances of nutrients have been formulated mainly from growth–response curves. The use of other criteria, especially those which exploit the biochemical role of nutrients, is discussed by reference to three different nutrients, namely thiamin, magnesium, and essential fatty acids.It is shown that erythrocyte transketolase activity provides a nutritional index of thiamin status in turbot (Scophthalmus maximus). The enzyme is saturated with coenzyme (thiamin pyrophosphate) at a dietary thiamin level of 2.6 mg/kg.Assessment of mineral requirements is shown to present special problems because complex interrelationships exist between some dietary minerals. It is shown that dietary magnesium deficiency (4 mg magnesium/100 g diet) leads to renal calcification in rainbow trout (Salmo gairdneri) at dietary calcium levels of 2.7 g/100 g (Ca: P ratio 1: 1). Elevation of dietary magnesium to 100 mg/100 g under these conditions gave freedom from pathology and enhanced growth.Ratios of certain fatty acids in the tissue phospholipids of rainbow trout are known to provide a useful index of essential fatty acid status. These ratios cannot be applied to turbot as this species does not chain elongate and desaturate 18-carbon acids at appreciable rates. Long chain polyunsaturated fatty acids of the ω3 series must be supplied preformed in the diet of turbot.

scholarly journals The effect of vitamin E and oxidized fish oil on the nutrition of rainbow trout (Salmo gairdneri) grown at natural, varying water temperatures

1984 ◽  
Vol 51 (3) ◽  
pp. 443-451 ◽  
Author(s):  
C. B. Cowey ◽  
Elizabeth Degener ◽  
A. G. J. Tacon ◽  
A. Youngson ◽  
J. G. Bell
Keyword(s):  
Rainbow Trout ◽  
Weight Gain ◽  
Vitamin E ◽  
Fish Oil ◽  
Water Temperature ◽  
Tocopheryl Acetate ◽  
Salmo Gairdneri ◽  
Oxidized Oil ◽  
Dietary Treatments ◽  
Oxidized Fish Oil

1. Groups of rainbow trout (Salmo gairdneri) of approximate mean initial weight 8 g were grown in outdoor tanks over a 14-week period at water temperatures between 12° (start) and 6° (end). Four diets were used. Two contained non-oxidized fish oil (120 g/kg) with or without supplementary DL-α tocopheryl acetate and two contained moderately oxidized fish oil again with or without DL-α-tocopheryl acetate. The measured selenium content of the diets was 0.10 mg/kg.2. No significant differences occurred as a consequence of the use of moderately oxidized oil compared with the corresponding treatments using non-oxidized oil. Significant differences did occur between dietary treatments that contained supplementary DL-α-tocopheryl acetate and those that did not. These differences applied to weight gain, haematocrit, erythrocyte fragility, mortalities, liver and muscle tocopherol concentrations and lipid peroxidation of liver mitochondria in vitro. Liver glutathione peroxidase (EC 1.11.1.9) activity was unaffected by the dietary treatments used and the proportions of fatty acids in polar lipids of liver and muscle were little changed by the diets used. Severe muscle damage occurred in trout given diets lacking supplementary DL-α-tocopheryl acetate.3. Previous experiments carried out on rainbow trout at a constant water temperature of 15° (Hung et al. 1981; Cowey et al. 1981, 1983), using diets lacking supplementary vitamin E, did not lead to differences in weight gain, pathological changes or mortalities.4. Vitamin E requirement may increase as water temperature decreases; minimum dietary requirements for vitamin E measured at a constant water temperature of 15° may not be valid under practical conditions where water temperatures vary over the year.

scholarly journals Studies on the nutrition of rainbow trout (Salmo gairdneri) Magnesium deficiency: the effect of feeding with a Mg-supplemented diet

1983 ◽  
Vol 50 (1) ◽  
pp. 121-127 ◽  
Author(s):  
D. Knox ◽  
C. B. Cowey ◽  
J. W. Adron
Keyword(s):  
Rainbow Trout ◽  
Magnesium Deficiency ◽  
Control Diet ◽  
Plasma Concentrations ◽  
Complete Recovery ◽  
Salmo Gairdneri ◽  
Control Group ◽  
Deficient Diet ◽  
Bone Ash ◽  
And Control

1. For a period of 8 weeks, rainbow trout (Salmo gairdneri), mean initial weight 21 g, were given either a low-magnesium or control diet containing 0·03 and 0·58 g Mg/kg diet respectively. Both groups of trout were then given the control diet for a further 11 weeks.2. Weight gains over the initial 8-week period were lowest in the Mg-deficient trout. Feeding the deficient fish the control diet rapidly improved growth rate until it was the same as that of the control trout.3. Plasma Mg was significantly lower in the Mg-deficient trout at week 8. Feeding with the control diet for 11 weeks did not increase plasma Mg. Few changes were observed in the plasma concentrations of the other electrolytes.4. Renal calcium concentrations were unaffected by dietary Mg levels. Similarly, the renal levels of phosphorus, sodium and potassium all fell within the range found in normal rainbow trout.5. Muscle Mg concentrations were reduced in those trout given the Mg-deficient diet. Feeding with the control diet for a further 11 weeks increased muscle Mg but the level was still significantly lower than that found in trout given the control diet for 19 weeks.6. The bone ash Mg concentration was significantly lower, and the Ca higher, in the deficient fish at week 8, when compared with the control group.7. When compared with the value at the start of the experiment, total bone Mg fell slightly in the deficient trout over the initial 8-week period, but increased in the control group of fish. Feeding with the control diet for a further 11 weeks increased total bone Mg in both Mg-deficient trout and control trout.8. The results show that the Mg deficiency imposed on the rainbow trout was of limited severity and almost complete recovery was obtained when the control diet was fed.

scholarly journals Acute Pathological Effects of Inorganic Mercury and Copper in Gills of Rainbow Trout

1984 ◽  
Vol 21 (1) ◽  
pp. 93-101 ◽  
Author(s):  
P.-Y. Daoust ◽  
G. Wobeser ◽  
J. D. Newstead
Keyword(s):  
Electron Microscopy ◽  
Rainbow Trout ◽  
Epithelial Cells ◽  
Light And Electron Microscopy ◽  
Inorganic Mercury ◽  
Salmo Gairdneri

Lesions induced in the gills of rainbow trout (Salmo gairdneri) by exposure to acutely lethal aqueous concentrations of inorganic mercury and copper were examined by light and electron microscopy. Lesions were most severe during the first 48 hours of exposure to the metals and were characterized primarily by apoptosis of lamellar epithelial cells and lamellar fusion. The latter process occurred either by simple apposition of adjacent lamellae to each other or through epithelial hypertrophy and hyperplasia. Except for hypertrophy of and increased number of primary lysosomes in lamellar epithelial cells of animals exposed to mercury, branchial lesions were not prominent in fish collected between 48 and 96 hours. The branchial lesions observed in this study are compared with pathological processes occurring in mammals.

scholarly journals The effect of dietary lysine levels on growth and metabolism of rainbow trout (Salmo gairdneri)

1984 ◽  
Vol 52 (1) ◽  
pp. 115-122 ◽  
Author(s):  
M. J. Walton ◽  
C. B. Cowey ◽  
J. W. Adron
Keyword(s):  
Rainbow Trout ◽  
Intraperitoneal Injection ◽  
Response Curve ◽  
Salmo Gairdneri ◽  
Hepatosomatic Index ◽  
Dietary Requirement ◽  
Saccharopine Dehydrogenase ◽  
Lysine Concentration ◽  
Low Levels ◽  
Dietary Treatments

1. Groups of rainbow trout (Salmo gairdneri; mean weight 5 g) were given diets containing 10, 12, 14, 17, 21, 24 and 26 g lysine/kg diet for 12 weeks.2. By analysis of the growth values the dietary requirement of lysine in this experiment was found to be 19 g/kg diet. A similar requirement value was obtained from a dose-response curve of expired 14CO2 (following an intraperitoneal injection of L-[U-14C]lysine) v. dietary lysine concentration.3. Liver concentrations of total lipid and carnitine and activities of lysine-α-ketoglutarate reductase (saccharopine dehydrogenase (NADP+, lysine-forming), EC 1. 5. 1. 8 ) in the liver were not significantly different in fish from the different dietary treatments. Hepatosomatic index, however, was higher in those fish given low levels of dietary lysine.

Temperature Selection of Rainbow Trout (Salmo gairdneri) Fingerlings in Vertical and Horizontal Gradients

1971 ◽  
Vol 28 (11) ◽  
pp. 1801-1804 ◽  
Author(s):  
R. W. McCauley ◽  
W. L. Pond
Keyword(s):  
Rainbow Trout ◽  
Salmo Gairdneri ◽  
Temperature Preference ◽  
Temperature Selection ◽  
Horizontal Gradients ◽  
Significant Difference ◽  
Preferred Temperatures ◽  
Laboratory Investigations ◽  
Horizontal Temperature Gradients ◽  
Selection Of

Preferred temperatures of underyearling rainbow trout (Salmo gairdneri) were determined in both vertical and horizontal temperature gradients. No statistically significant difference was found between the preferred temperatures by the two different methods. This suggests that the nature of the gradient plays a lesser role than generally believed in laboratory investigations of temperature preference.

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