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Trivalent chromium is considered an essential element in the nutrition of both animals and humans. Animal studies confirm many beneficial effects of organic and inorganic chromium compounds on carbohydrate, protein and lipid metabolism in the body. Glucose tolerance factor (GTF) has been demonstrated to involve an active form of trivalent chromium, which sustains normal glucose metabolism. Cr (III) compounds form enzymes and ribonucleic acids, accelerate blood clotting and increase β-glucuronidase activity. Chromium also participates in antioxidant processes, in the synthesis of RNA and DNA and in the immune response, as well as affects secretion of hormones and some vitamins. It has been demonstrated that chromium improves lean body mass in animals, increases growth rate and feed conversion and improves feed intake and energy efficiency. Organic chromium reduces mortality and improves animal reproduction parameters. It also enhances immunity and strengthens response to preventive vaccination. It has been noted in many animal species that a diet low in chromium leads to deficiency symptoms, such as reduced feed intake, lower weight gains, reproductive disorders and increased lipid levels. Chromium deficiency can also result from stress. Moderate chromium deficiency is a risk factor of ischemic heart disease with myocardial infarction. Such a condition may pose a great risk of coronary artery disease. Dietary chromium requirement of an animal body is probably 300 μg Cr/kg d.w. of feed, which is usually satisfied by the ration provided. The highest concentration of chromium is found in the hair, skin and teeth, followed by the liver, kidneys, spleen, and slightly lower in the heart, muscles, pancreas, lungs, bones and brain. Chromium absorption rates in the human intestine range between 0.5 and 2% of the daily intake of inorganic Cr forms, and from 25 to 30% of the element ingested as organic complexes. Clinical studies show that the kinetics of chromium excretion from the system are complex and can be described by a multi-range model, the half-life ranging from 13 min to 192 days. Dietary chromium nanocomposite supplementation (CrNano) used in pigs nutrition has significantly increased Cr content in the blood, longissimus muscle, heart, liver, kidneys, jejunum and ileum. Chromium nanocomposite supplementation acts more effectively on the tissues and, as a consequence, increases the accumulation of the element.
Diets supplemented with Mytilus galloprovincialis from polluted and non-polluted waters and their influence on zinc content in liver of rats loaded with cholesterol. Mussels may reflect the environmental problems that the ecosystem faces. Mytilus galloprovincialis is widely used as an indicator of water pollution in biological monitoring studies. These mussels are filter feeders and may accumulate important ecosystem pollutants what in turn may pose a potential risk to other organisms in the food chain. The aim of the study was to determine zinc content in the diets supplemented with mussels from polluted and non-polluted areas and in the livers of rats fed these diets for 30 days. The zinc content in the diets with mussels from contaminated and noncontaminated waters and in rat livers was examined using a flame atomic absorption spectrophotometry (Perkin-Elmer 1100B). The slight increase in zinc content from 73.2 ±1.2 mg/ /kg in ch diet (control with 1% of cholesterol) to 77.2 ±0.5 mg/kg in the diet with mussels from polluted site was found, but zinc content in all diet was within the normal limits reviewed by McDowell (1992) – 40 to 100 ppm. Zinc content in the diet supplemented with mussels from nonpolluted site (73.7 ±3.7 mg/kg) was similar to that found in ch diet. It can be concluded that cholesterol does not affect zinc bioaccumulation. However, prolonged consumption of mussels from contaminated sites may increase accumulation of zinc in the liver of rats.
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