A silicon requirement for normal skull formation in chicks.

Carlisle, Environmental and Nutritional Sciences, School of Public Health, University of California, Los Angeles, CA 90024

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Studies were undertaken to investigate the effect of feeding a silicon (Si)-deficient diet containing a natural protein in place of the crystalline amino acid-based diets used in earlier studies. Feeding this Si-deficient basal diet with or without supplemental Si to day-old cockerels under trace element-controlled conditions resulted in the production of skull abnormalities in the deficient chicks under conditions of near optimal growth.


On macropathological examination, gross changes were found in the architecture of the skulls of the deficient chicks; the frontal area was narrower and the dorsal median line at the frontal parietal junction was depressed with a narrowing both posterior and laterally, forming a stunted parietal, occipital and temporal bone area. X-ray and histological examination of this area showed less trabeculae and calcification. Biochemical analyses of the skull frontal bones for bone mineral, non-collagenous protein, hexosamine and collagen demonstrated that the frontal bones from the Si-deficient chicks had a significantly reduced collagen content. In this study, the major effect of Si appears to be on the collagen content of the connective tissue matrix, a deficiency resulting in abnormal skull matrix formation. Support is given to the earlier postulate that Si is involved in an early stage of bone formation.


In vivo requirement for silicon in articular cartilage and connective tissue formation in the chick

Edith M. Carlisle, Environmental and Nutritional Sciences, School of Public Health, University of California, Los Angeles, CA 90024

Studies were undertaken to determine further effects of silicon deficiency in the chick. The diet and experimental conditions were the same as those used in previous studies to demonstrate the essentiality of silicon for growth and development. Skeletal and other abnormalities involving glycosaminoglycans in formation of articular cartilage and comb connective tissue were found to be associated with silicon deficiency. The bones of 1 day-old deutectomized cockerels fed a silicon supplemented diet and killed at 4 weeks of age had significantly greater amounts of articular cartilage and water as compared with the silicon deficient group and also a greater proportion of hexosamine in the cartilage. The greater water con tent in bones of the silicon supplemented chicks coincided with a larger content of glycosaminoglycans in the articular cartilage. A similar relationship was obtained in cockerel comb. In addition to larger amounts of con nective tissue and of total hexosamine in combs of the supplemented group, a higher percentage of hexosamine and a higher silicon content was found. These findings provide the first evidence for a requirement for silicon in articular cartilage and connective tissue formation and that the site of action of silicon is in the glycosaminoglycan-protein complexes of the ground substance.

Silicon: an essential element for the chick

Edith M. Carlisle, Environmental and Nutritional Sciences, School of Public Health, University of California, Los Angeles, CA 90024

Silicon is required for normal growth and development in the chick when a low silicon diet is fed in a trace element controlled environment. Day-old deutectomized cockerels fed a purified amino acid diet showed significantly retarded growth and development within 2 to 3 weeks. Chicks fed the same diet plus a silicon supplement showed 50 percent higher growth and normal development. Silicon meets the criteria for an essential trace element. BACK


Effect of diatomaceous earth on parasite load, egg production, and egg quality of free-range organic laying hens

C. Bennett, A. Yee, K.M. Cheng, Y. J. Rhee; Poultry Science Association Journal

The effectiveness of diatomaceous earth (DE) as a treatment against parasites and to increase feed efficiency and egg production of organically raised free-range layer hens was evaluated in 2 breeds of commercial egg layers [Bovan Brown (BB) and Lowmann Brown (LB)] that differ in their resistance to internal parasitic infections. Half the hens of each breed were fed diets supplemented with DE (2%). Their internal parasite loads were assessed by biweekly fecal egg counts (FEC) and by postmortem examination of the gastrointestinal tract. Supplementing DE in diets of LB hens, the more parasite-resistant breed, did not significantly affect their FEC and adult parasite load. However, BB hens treated with dietary DE had significantly lower Capillaria FEC, slightly lower Eimeria FEC, fewer birds infected with Heterakis, and significantly lower Heterakis worm burden than control BB hens. Both BB and LB hens fed the diet containing DE were significantly heavier, laid more eggs, and consumed more feed than hens fed the control diet, but feed efficiency did not differ between the 2 dietary treatments. Additionally, BB hens consuming the DE diet laid larger eggs containing more albumen and yolk than hens consuming the control diet. In a subsequent experiment, the effectiveness of DE to treat a Northern fowl mite (Ornithonyssus sylviarum) infestation was tested. Relative to controls, both breeds of hens that were dusted with DE had reduced number of mites. The results of this study indicate the DE has the potential to be an effective treatment to help control parasites and improve production of organically raised, free-range layer hens.


Silicon as an essential trace element in animal nutrition

Edith M. Carlisle, Environmental and Nutritional Sciences, School of Public Health, University of California, Los Angeles, CA 90024

Within the last decade silicon has been recognized as participating in the normal metabolism of higher animals and as being an essential trace element. Silicon is found to perform an important role in connective tissue, especially in bone and cartilage. Bone and cartilage abnormalities are associated with a reduction in matrix components, resulting in the establishment of a requirement for silicon in collagen and glycosaminoglycan formation. Silicon’s primary effect in bone and cartilage is on the matrix, with formation of the organic matrix appearing to be more severely affected by silicon deficiency than the mineralization process. Additional support for silicon’s metabolic role in connective tissue is provided by the finding that silicon is a major ion of osteogenic cells and is present in especially high concentrations in the metabolically active state of the cell; furthermore, silicon reaches relatively high levels in the mitochondria of these cells. Further studies also indicate that silicon participates in the biochemistry of the subcellular enzyme-containing structures. Silicon also forms important interrelationships with other elements. Although it is clear from the body of recent work that silicon performs a specific metabolic function, a structural role has also been proposed for it in connective tissue. A relationship established between silicon and ageing probably relates to glycosaminoglycan changes.


Effect of dietary silicon and aluminum on silicon and aluminum levels in rat brain

Carlisle EM, Curran MJ, Environmental and Nutritional Sciences, School of Public Health, University of California, Los Angeles, CA 90024


This preliminary study was undertaken to investigate the effect of dietary silicon and aluminum on levels of these elements in brain. Two ages of rats, 22 day and 10 month, were assigned to 1 of 4 diets:

1) low silicon

2) low silicon plus aluminum

3) silicon supplemented

4) silicon supplemented plus aluminum

Rats were 23 and 28 months old upon termination of the experiment. Twelve brain regions were analyzed for silicon and aluminum.

Regional variations in silicon, which were independent of dietary silicon supplementation, suggest that silicon may be an essential element in brain. Aluminum supplementation decreased the silicon content in selected brain regions, including those thought to be involved in Alzheimer disease.


A relationship has been established between silicon, aluminum and age. In 23-month rats, aluminum supplementation did not increase brain aluminum content. By contrast, in 28-month rats, aluminum supplementation of the low silicon diet increased brain aluminum content in most regions. No increase occurred in silicon supplemented groups of the same age. Dietary silicon supplementation thus appeared to be protective against aluminum accumulation in aging brain.

Silicon: an overlooked trace mineral

LE Magazine April 2003, Raport

Bioavailability and efficacy of silicon supplements. When selecting a silicon supplement, the most important considerations should be safety and bioavailability. (Bioavailability is a complex term for the degree of absorption and the biological response to the silicon compounds which are present in the product.)


Organic silicon compounds, which are laboratory synthesized, contain silicon-carbon bonds. These molecules are normally not present in biological systems and can be very toxic. For this reason it is safest to use silicon compounds that are already present in nature or compounds that are the derivatives of natural products. Common silicon supplements include:

  • Plant extracts
  • Colloidal silicon gel
  • Stabilized orthosilicic acid

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