SB/RB should not be fed to infants because they are nutritionally inadequate and contain Mn at levels which may present an increased risk of adverse neurological effects if used as a sole source of nutrition.

No abstract

Nephrocalcinosis (NC) in female rats can complicate the interpretation of nutritional or toxicological studies involving the kidney. Recent reformulations of standardized rodent diets such as AIN-93G and NTP-2000 sought to optimize the dietary Ca:P ratio, an important etiologic factor in NC. The effect of increasing intakes of Ca and P together at their optimal molar ratio has not been systematically studied. Weanling female and male Sprague-Dawley rats were fed modified AIN-93G diets containing Ca and P at AIN-93G diet concentrations (5 g Ca + 3 g P/kg diet), with multiples of Ca and P at the same ratio (1.5x = 7.5 g Ca + 4.5 g P, 2.5x = 12.5 g Ca + 7.5 g P, 4.0x = 20.0 g Ca + 12.0 g P/kg diet), or Ca and P at concentrations found in the AIN-76A diet (5 g Ca + 5 g P/kg diet), for 16 wk. Incidence and severity of NC and kidney Ca concentration in female rats increased with dietary Ca and P, although not to levels in female rats fed at the AIN-76A Ca:P ratio. Male rats showed limited evidence of kidney Ca accumulation or NC. The concentrations of dietary Ca and P, as well as the ratio of these two elements, affected development of NC in female rats.

No abstract

Experiments were conducted to test the commonly held assumption that analysis of a portion of rat liver is representative of the elemental concentration of the whole organ. Male Sprague-Dawley rats (initial body weight approximately 250 g) fed a chow diet or weanling male Long-Evans rats (initial body weight approximately 50 g) fed a semipurified diet with or without copper in the mineral premix were sacrificed after 4 wk on their respective diets and livers were dissected into seven portions representing major anatomical divisions of this organ. Elemental analyses by atomic absorption spectroscopy (calcium, magnesium, iron, zinc, copper, manganese), atomic emission spectroscopy (sodium, potassium), or colorimetric assay (phosphorus) demonstrated no statistically significant differences in composition of these nine elements among anatomical regions of liver. Dietary copper deficiency led to equivalently reduced copper concentration in all portions of rat liver and did not cause any other significant alterations in liver composition of these nine elements within the 4 wk of these studies. These results confirm the validity of the common assumption that analysis of a portion of rat liver can be representative of the elemental composition of the whole organ. This conclusion will allow more analyses to be performed on fewer animals, thereby reducing animal use and reagent costs without sacrificing analytical accuracy.