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

Abstract

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 l), 26 (diets 2 and 3) and 40 (diets 4 and 5), Ca:P being approximately 1 : I 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 gjkg, 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. 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.

Pathologic Findings in Weedy (Phyllopteryx taeniolatus) and Leafy (Phycodurus eques) Seadragons

“…What role these supplementation regimes, if any, play in the formation of the mineralization of the swim bladder would seem to be worthy of study. Renal calcinosis has been described in salmonids fed synthetic diets deficient in magnesium, 7 and the role of dietary magnesium also probably warrants investigation. Metastatic mineralization of tissues has been reported in salmonids subjected to prolonged, elevated carbon dioxide levels in the water, although tissues other than the swim bladder were affected.…”

Acid stress in respect to calcium and magnesium concentrations in the plasma of perch during maturation and spawning

“…Fish tnsues are known to react to a Mg deficiency by means of hypercalcaemia, as observed in the kidney and muscles (Cowey et al 1977, Knox et al 1981 and to some extent also in the vertebrae (Ogino & Chiou 1976). A tendency for increased Ca concentrations in the ova was observed here in the acid lake.…”

Accumulation of heavy metals in rainbow trout Salmo gairdneri (Richardson) maintained on a diet containing activated sewage sludge

“…Low calcium, in particular, increases the absorption of heavy metals such as manganese, copper, zinc, silver, cadmium, lead and iron by plants (Schroeder, 1965), while high dietary calcium has a protective action against the adverse effects of lead and zinc in pigs (Hsu et al, 1975). Shortages of some of the major cations have also been reported to affect growth adversely in fish (Dove et al, 1976;Cowey et al, 1977). There is no evidence of such an effect in this study, but it is possible that a supplement containing these cations might have reduced the rate of uptake of the heavy metals.…”