Clinical Biochemistry of Domestic Animals (Sixth Edition) - UMK ...

Chapter 22
Trace Minerals
Robert B. Rucker
Department of Nutrition
College of Agriculture and Environmental
Sciences, University of California, Davis
Davis, California
Andrea J. Fascetti
Department of Molecular Biosciences
School of Veterinary Medicine
University of California, Davis
Davis, California
Carl L. Keen
Department of Nutrition
College of Agriculture and Environmental
Sciences, University of California, Davis
Davis, California
I. INTRODUCTION
A. General Properties of Minerals
B. Typical Configurations of Metal Complexes
C. Biological Perspectives
II. COBALT
A. Cobalt Function
B. Absorption and Transport
C. Disorders of Cobalt Metabolism
III. COPPER
A. Copper Distribution
B. Copper Functions
C. Dietary Copper
D. Copper Metabolism, Absorption, and Transport
E. Evaluation of Cu Status
IV.
MANGANESE
A. Manganese Distribution
B. Manganese Function
C. Dietary Manganese
D. Manganese Metabolism, Absorption, and Transport
E. De ficiency and Excesses
F. Evaluation of Manganese Status
V. MOLYBDENUM
A. Molybdenum Distribution
B. Molybdenum Functions
C. Molybdenum Metabolism, Absorption, and Transport
D. Other Disorders
VI.
SELENIUM
A. Dietary Selenium
B. Selenium Functions
C. Selenium Metabolism, Absorption, and Transport
D. Disorders of Selenium Metabolism
E. Evaluation of Selenium Status
VII. ZINC
A. Zinc Distribution
B. Functions of Zinc
C. Dietary Zinc
D. Zinc Metabolism, Absorption, and Transport
E. Zinc Deficiency
F. Zinc Toxicity
G. Evaluation of Zinc Status
VIII. CONCLUDING COMMENTS
REFERENCES
I . INTRODUCTION
Of the 103 elements in the periodic table, about 30 are
presently considered essential or important for the normal
health and growth of animals. Of these, 16 are often designated
as essential trace elements, a classification initially
based on the difficulty of measuring such elements with
precision in biological tissues. Although the development
of new instrumentation has greatly facilitated measurement,
the term trace elements has been retained and is still
commonly applied to those elements that occur in the body
at concentrations in the submicromolar to micromolar
range ( Fraga, 2005 ; O’Dell and Sunde, 1997 ; Reilly, 2004 ;
Ullrey, 2002 ).
This chapter focuses on six elements—cobalt (Co), copper
(Cu), manganese (Mn), molybdenum (Mo), selenium (Se),
and zinc (Zn)—to illustrate the concepts important to trace
element metabolism and disease ( Reilly, 2004 ). These elements
have been chosen because there is evidence that
perturbations in their metabolism are relatively common.
Other biologically active trace elements, although potentially
important, often require special conditions or long
periods of deprivation before signs of deficiency are recognized,
and exposures at 10 to 100 times normal intakes
are required before toxic signs are observed (Subcommittee
on Dairy Cattle, National Research Council [NRC], 2001;
Subcommittee on Mineral Toxicity in Animals, NRC, 1980).
In conventional settings, deficiencies of elements such as
vanadium, chromium, silicon, nickel, and tin are rarely
encountered. Further, arguments for their nutritional essentiality
remain controversial. If there is a nutritional need, it
is likely to be in the microgram per kilogram of diet range,
whereas the relative need for Co, Cu, Zn, Mn, Mo, and Se
approaches, or exceeds, amounts in the milligram per kilogram
of diet range ( Tables 22-1 and 22-2 ).
A . General Properties of Minerals
Most elements accumulate in tissues to some extent. The
essential elements, however, are distinguished in that
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