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Library of Congress Catalog Card Number: 92-25242 ISBN: 0-8155-1312-7 Printed in the United States Published in the United States of America by The Roles of amino acid chelates in animal

THE ROLES OF AMINO ACID CHELATES

IN ANIMAL NUTRITION

No part of this book may be reproduced or utilized in

any form or by any means, electronic or mechanical,

including photocopying, recording or by any

informa-tion storage and retrieval system, without permission

in writing from the Publisher.

Library of Congress Catalog Card Number: 92-25242

ISBN: 0-8155-1312-7

Printed in the United States

Published in the United States of America by

The Roles of amino acid chelates in animal nutrition / edited by H DeWayne Ashmead.

Th i s book wi 11 be of great interest to anyoneconcerned with animal feeds and feeding programs whetherone is studying bovine, porcine, equine, avian or lowervertebrate (fish and eel) nutrition This information

is critical to the success of an animal feeding program.Somet imes the di fference between a successful and afailing program can be traced to mineral deficiencieswhich cause either abnormal growth, reduced milkproduction, interrupted fertility and breeding,compromised immune system integrity and/or decrement innormal hemoglobin concentration Increasedmorbidity/mortality rates can make a profitable animalfeeding program into a financial failure overnight whenthe replacement costs for a prize animal are considered.These abnormalities, and others, are addressed in thepages that follow

From 25 controlled studies by 42 different authors

in five different countries a diverse array of data ispresented These data val i date the effect i veness ofmineral nutrients presented as amino acid chelates whencompared with the ionic forms derived from the inorganicsal ts These stud i es further support the resul ts ofnumerous laboratory experiments showing increasedabsorption, assimilation and reduced toxicity of theforms of minerals chelated to amino acids With littlecost and effort animals can be supplemented with aminoacid chelates which will promote, with little risk ofoverdose, a fuller genetic potential achievement as far

as mineral requirements are concerned Results of thissupplementation are reflected in increased growth,immunological integrity, and more consistentreproduction (increased ovulation and conception afterfirst service) as a result of increased bioavailability

of these chelated forms

v

VI Introduction

Of novel interest are the reports showing a

protein sparing as a result of amino acid chelate

minerals needs further scrutiny in feeding programs in

other species

Darrell J Graff, Ph.D

Weber State UniversityOgden, Utah, U.S.A

A NOTE TO THE READER

In the late 1800's, many of the fundamentalconcepts of che1at ion chemi stry were evo1vi ng Chemi stsbegan to recognize that certain atoms could exist inmore than one valence state, but could not comprehendhow atoms with more than one valence could form a highlystable compound

Alfred Werner, a German chemist, was the first tobreak with traditional thinking and propose an entirelynew molecular structure to describe these highly stable

which he called "complexes", remained intact through a

wrote, "If we think of the metal ion as the center ofthe whole system, then we can most simply place the

octahedron."(1) For the first time a chelate had beendescribed

Werner further refined this revolutionary concept

called the "principal valency", is now termed theoxidation state, or oxidation number, of the metal Thesecond valency, which he called the "auxiliary valency",represents the number of ligand atoms associated with

coord i nat i on number of the metal.(2-7) Werner's conceptswere fundamental to the comprehension of chelates

The term, "chelate", was finally used by Morganand Drew, in 1920, to describe the molecular structure

chelating molecules that had been discovered were those

VII

VIII A Note to the Reader

with two points of attachment It was this caliper-likemode of attaching the ligand (the chelating molecule) tothe metal atom that led Morgan and Drew to suggest theword "chelate" to describe the molecule.(8) The word isderived from the Greek word "chele", meaning lobster'sclaw The word, IIchelatell

, was originally used as anadjective It later became a more versatile word andtoday i s used as an adj ect i ve, adverb, or noun Theligands are chelating agents, and the complexes theyform are metal chelates

Because the claw, or ligand, held the cation, themetal was no longer free to enter into other chemicalreactions Thus it quickly became evident that when ametal was che1ated, the chemi cal and phys i calcharacteristics of the constituent metal ion and ligandswere changed This had far reaching consequences in therealms of chemistry and general biology In spite ofthe knowledge of what chelation could do to and for ametal ion, it was not until the early 1960's that anyonethought seriously about using this molecule fornutritional purposes

At that period, a handful of investigators,independent of each other, each conceived the idea that

if a metal ion could be chelated before feeding it toanimals, the ligand would sequester the cation andprevent it from entering into various absorptioninhibiting chemical reactions in the gut Thetheoretical consequence was greater nutritional uptake

of the ions

Two schools of thought quickly developed One,led by the pioneering research of Albion Laboratories,Inc., proposed that amino acid chelates were the properchelates to enhance mineral absorption As attested by

a large number of research reports, lectures, andpublications based on the research efforts both

A Note to the Reader IX

coordinated and conducted by this organization, the use

of amino acid chelates in animal nutrition were bothpositive and highly encouraging At that point in timethese amino acids were called "metal proteinates"instead of chelates

Concurrently, with the development of the aminoacid chelates, a second school of thought approachedanimal nutrition with synthetic chelates based onethylenediaminetetraacetic acid (EOTA) The theory wasthe same as before The EOTA ligand would chelate thecation and protect it from chemical reactions in thegut While it successfully accomplished its mission interms of protect ion, it genera11 y fa i 1ed to enhancemineral nutrition because it formed chelates that weretoo stable The biological ligands in the animals'bodies were incapable of extracting the cations from theEOTA chelates, even after they were absorbed into theblood Thus, the EOTA chelates were returned to thelower bowels or excreted into the urine still protectingthe cations that the animal s were supposed to haveutilized As Bates, et li., concluded, even thoughchelation plays a dominant role in mineral absorption,

"chelation does not, in itself, insure efficient uptakebecause the absorption of the ferric chelates of EOTA,NTA, and gluconate were not significantly different thanthat of ferrous sul fate ,,(9)

These synthetic chelates were heavily promoted inthe decade of the 60's and the early part of the 70's.When they could not deliver the enhanced mineralnutrition promised by the chelation concept, allnutritional products using the word "chelation" lostfavor with most animal nutritionists The "c" wordbecame a word to avoid if one wished to amicably discussanimal nutrition

x ANote to the Reader

It was for this reason metal proteinates became a

term, the words evolved out of the concept of complexing

acceptable terminology because they successfully avoidedmention of the "ell word There was a problem with that

describe a metal proteinate

By 1970, Albion Laboratories, Inc had suppliedthe necessary research to allow the American Association

of Feed Control Officials (AAFCO) to officially definemetal protei nates as the product resul t i ng from thechelation or complexing of a soluble salt with aminoacids and/or hydrolyzed protein

became evident that this definition was too broad to

proven were efficacious Many companies were not makingchelates, but could still have their products defined as

making chelates, were not making products that could be

chelate over 1,500 daltons can not be absorbed), or themineral was bonded to whole or partially hydrolyzed

release of the metal to competing reactions in the chymesimilar to those facing cations derived from any otherfeedstuff)

Because of the confusion among feed companies intrying to decide which metal proteinates were valuablesources of the added mineral nutrition, which metalproteinates were supported by scientific studies, andwhich were "me too" products that had no support data oftheir own, Albion Laboratories, Inc applied to AAFCO

A Note to the Reader XI

nutritionists due to their earlier experiences withsynthetic chelates, Albion still decided to call theproducts by their true name - amino acid chelates

After several years of debate within the AAFCOorganization, a debate which was primarily fueled bycompanies using Albion's research to promote dissimilarproducts ascribed to the proteinate definition, a new

for a metal amino acid chelate rectified the looseness

of the metal proteinate definition by including absoluterequirements for molecular weights, molar ratios ofami no ac ids to metal s, and the abso1ute presence of

disbarred the complexing of metals with protein orpeptides, both of which require further digestion before

absorbed was thus disallowed

As defined by the American Association of FeedControl Officials, a metal amino acid chelate is litheproduct resulting from the reaction of a metal ion from

a soluble salt with amino acids with a mole ratio of onemole of metal to one to three (preferably two) moles of

average weight of the hydrolyzed amino acids must beapproximately 150 and the resulting molecular weight ofthe chelate must not exceed 800."( 0

)

investigator is affiliated is noted on the list ofcontributors and at the beginning of each chapter

XII A Note to the Reader

The book is divided into several sections so that

a reader, who may not wish to read the entire book, canquickly turn to his or her own area of primary interest.Separate sections are devoted to cattle, pigs, poultry,horses and fish The beginning section discusses thefundamentals of amino acid chelation as they relate tothe various aspects of animal nutrition discussed ineach of the subsequent sections It is stronglyrecommended that the reader who has primary interest inonly one species of animal still read this first sectionprior to addressing the species of interest The firstsection will provide numerous basic concepts that willenhance the reader's comprehension of the data in thesubsequent sections

For the animal nutritionist, veterinarian, andothers whose interests range further than a s i ngl especies, reading the book in its entirety isrecommended As noted above, it is divided into fiveadditional sections beyond the introductory section plus

a summary The second sect i on deal s wi th severalaspects of dairy and beef cattle mineral nutrition.Some topics discussed include immunity, fertility,increased mi 1k product ion, greater growth rates, andimproved feed conversions The third section addressesseveral important concepts of swine nutrition includingbaby pig anemia, improved reproductive capacity in oldersows, and leaner pork Poultry is handled in the fourthsection Topics include improvements in breeder/broileroperations, egg production and enhanced turkeyproduction The next section deals with equinenutrition as it relates to fertility and proper growthand development of the legs The last section dealswith enhanced performance in fish and eels

Although the data are conclusive in most cases,the research reported in these sections is by no meanscomplete In many instances the editor was faced with

A Note to the Reader XIII

making painful decisions as to whose research toinclude, or not to include, in order to avoid excessiverepetition In spite of these efforts, some repetitionwas unavoidable, but hopefully not redundant

The purpose of reporting this research in the form

of a book has been two-fold The first is to stimulateothers to piek up the torches that have been lighted bythe researchers who have contributed to this book and tocont i nue onward from where they stopped The secondpurpose is to make the "e" word once again an acceptableword in animal nutrition circles

H DeWayne Ashmead

XIV ANote to the Reader

References

1. Werner, A., "Beitrag zur KonstitutionAnaorgan i scher Verbi ndungen," Z., anorg u all gem.Chern., 3:267, 1893

2 Werner, A and Miolati, A., Z physik Chern.(Leipzig), 14:506, 1894

3 Werner, A and Vilmos, Z "Beitrag zur KonstitutionAnaorganischer Verbindungen," l. anorg u allegem.Chern., 21:153, 1899

4 Werner, A., "Ueber Acetyl acetonverbi ndungen desPlatins," Ber deut chern Ges., 34:2584, 1901

8 Morgan, G and Drew, H., "Research on residualaffinity and coordination II Acetylacetones ofselenium and tellurium," J. Chern Soc., 117:1456,

1920

9 Bates, G., et li., "Facil itation of iron absorption

by ferric fructose," Am J Cline Nutr., 25:983,1972

10 Haas, E., et li., eds., Official Publication 1989

(Atlanta: American Association of Feed ControlOfficials, Inc.) 159, 1989

Ashmead, H DeWayne

Albion Laboratories, Inc.

Clearfield, Utah, U.S.A.

Ashmead, Harvey H.

Albion Laboratories, Inc.

Clearfield, Utah, U.S.A.

Turin, Italy

Coffey, Robert T.

Newton, Iowa, U.S.A.

Corradi, Fulvio University of Bologna Bologna, Italy

Cuiton, Louis Productos Quimico Agropecuarios, S.A.

Mexico City, Mexico

Cuplin, Paul Idaho State Fish and Game Department

Boise, Idaho, U.S.A.

Darneley, A H.

Dorset, England

Ferrari, Angelo Zoopropylactic Institute of Piedmont

Liguria and Valle d'Aosta Italy

Iowa State University

Ames, Iowa, U.S.A.

Maletto, Silvano University of Turin Turin, Italy

Manspeaker, Joseph E University of Maryland College Park, Maryland, U.S.A.

Hildebran, Susan

Wapakoneta, Ohio, U.S.A.

Hunt, John

Sugar Creek Veterinary Service

Greenfield, Indiana, U.S.A.

Beijing, China

Parisini, Paolo University of Bologna Bologna, Italy

Quarantelli, Afro University of Parma Parma, Italy

Contributors XVII Robl, Martin G.

Lake Hamanako Branch Shizuoka, Japan

Volpelli, L A.

University of Bologna Bologna, Italy

Wakabayashi, T akaaki Eisai, Co., Ltd.

Tokyo, Japan Xian-Ming, Cao Beijing Agriculture Science Institute

Beijing, China

Van Ping, Zhou Beijing Agriculture Science Institute

Beijing, China

Zunino, Hugo University of Chile Santiago, Chile

To the best of the Publisher's knowledge the information contained in this publication is accurate; however, the Publisher assumes no responsibility nor liability for errors or any consequences arising from the use of the information contained herein Final determination of the suitability of any infonnation, procedure, or product for use contemplated by any user, and the manner of that use, is the sole responsibility of the user.

The book is intended for informational purposes only The reader is warned that caution must always be exercised when dealing with chemicals, products, or procedures which might

be considered hazardous Expert advice should be obtained at all times when implementation is being considered.

Mention of trade names or commercial products does not constitute endorsement or recommendation for use by the Publisher.

XVIII

AMINO ACID CHELATION

John B Herrick

2 FACTORS WHICH AFFECT THE INTESTINAL

H DeWayne Ashmead and Hugo Zunino

3 COMPARATIVE INTESTINAL ABSORPTION AND

SUBSEQUENT METABOLISM OF METAL AMINO ACID

H DeWayne Ashmead

4 INCREASING INTESTINAL DISACCHARIDASE

ACTIVITY IN THE SMALL INTESTINE WITH

Silvano Maletto and Germano Cagliero

XIX

xx Contents

5 EVALUATION OF THE NUTRITIONAL

Silvano Maletto and Germano Cagliero

6 AN ASSESSMENT OF LONG TERM FEEDING OF

Robert B Jeppsen

SECTION 2 CATTLE

7 THE USE OF AMINO ACID CHELATES TO ENHANCE

Robert T Coffey

8 THE USE OF AMINO ACID CHELATES IN BOVINE

Joseph E Manspeaker and Martin G. Robl

9 THE ROLE OF COPPER IN BEEF CATTLE FERTILITY 154

J Robert Kropp

10 THE USE OF AMINO ACID CHELATES IN HIGH

Andrea Formigoni, Paoli Parisini, and Fulvio Corradi

11 THE FEEDING OF AMINO ACID CHELATE

James A. Boling

SECTION 3 SWINE

12 THE ROLE OF IRON AMINO ACID CHELATE IN

PIG PERFORMANCE 207

H DeWayne Ashmead

13 THE EFFECT OF IRON AMINO ACID CHELATE ON

Cao Xian-Ming, Feng Ming Uan, and Zhou Yan Ping

14 THE EFFECT OF AMINO ACID CHELATED IRON IN

P Parisini, F Ricci Biti, L.A Volpelli andC. Sacchi

Contents XXI

15 IMPROVING REPRODUCTIVE PERFORMANCE WITH

17 THE EFFECT OF AMINO ACID CHELATES IN CHICK

David Atherton

18 THE DYNAMICS OF FEEDING AMINO ACID CHELATES

TO BROI LERS 302

Alberto Bonomi, Afro Quarantelli, Paola Superchi,

Alberto Sabbiono, and Luigina Lucchelli

19 GROWTH RATES AND FEED CONVERSION IN BROilER

Louis Cuitun and Eduardo Guillen

20 THE USE OF AMINO ACID CHELATES IN GROWING

TURKEYS 330

Alberto Bonomi, Afro Quarantelli, Paola Superchi,

Alberto Sabbiono, and Danielle Bolsi

21 THE ROLE OF AMINO ACID CHELATES IN

OVERCOMING THE MALABSORPTION SYNDROME

Angelo Ferrari and Germano Gagliero

22 THE VALUE OF AMINO ACID CHELATES IN EGG

Martin G. Robl and RichardJ. Forta

25 COPPER-RESPONSIVE EPIPHYSITIS AND TENDON

Susan Hildebran and John Hunt

SECTION 6 FISH

26 THE USE OF AMINO ACID CHELATES IN RAINBOW

Harvey H Ashmead and Paul Cuplin

27 THE USE OF ZINC AMINO ACID CHELATES IN HIGH

CALCIUM AND PHOSPHORUS DIETS OF RAINBOW

Ronald W Hardy and Karl D Shearer

28 THE EFFECTS OF IRON AMINO ACID CHELATE IN

Katsuhiro Suzuki, Yoshito Iwahasi, Takeharu Takatsuka

and Takaaki Wakabayashi

SECTION 7 SUMMARY AND CONCLUSION

H DeWayne Ashmead

Section 1. AMINO ACID CHELATION

Chapter 1

MINERALS IN ANIMAL HEALTH

John B Herrick*

Iowa State University

Sci ent i sts have long known that traces of mostelements exist in animal tissue, but in many cases theybelieved that those minerals were contaminants ratherthan functional entities As analytical methods haveimproved, many elements that were once thought to becontaminants have been shown to be essential to the lifeand well being of the animals.(1) Thus, a mineral is nowbelieved to be essential if (a) it is present in allhealthy tissue, (b) its concentration from one animal tothe next is generally constant, (c) its withdrawal fromthe body results in reproducible physiological andstructural abnormalities, (d) its addition prevents orreverses those abnormal it i es, (e) the defi ci ency- inducedabnormalities are accompanied by specific biochemicalchanges, and (f) these biochemical changes can beprevented or cured with the addition of the mineral .(2)

The three major roles of essential minerals are todirectly or indirectly function in supplying energy, toindirectly and directly aid in growth and maintenance ofthe body tissues, and fin~lly to assist in theregulation of body processes.() The need for chromium

to potentiate insulin and the involvement of phosphorus

in the ATP mol ecul e are two exampl es of the di verseroles of minerals in energy production In their roles

of growth and maintenance of tissues, mineralscontribute to the rigidity of the bones and teeth and

* The original draft was written while associated

with Iowa State U Dr Herrick is currentlyretired and working as a consultant

3

4 The Roles of Amino Acid Chelates in Animal Nutrition

are an important part of protein and lipid fractions ofthe animal body As regul ators of body processesminerals preserve cellular integrity by osmoticpressures and are a component of many enzyme systemswhich catalyze metabolic reactions in biologicalsystems Most minerals function in more than one role

As an example, calcium is used in large amounts by thebody for synthesis of osseous tissue Phosphorus alsocontributes structurally and yet is a key element in theuse of energy by the body Furthermore, cobalt has aregulatory role (through vitamin 8-12) rather thancontributing quantitatively to tissue synthesis, but itseffect on growth i s as dramat i c as that of cal ci urn.Other elements play essential roles, as well

Minerals which are involved in several metabolicprocesses are more likely to be interrelated with otherminerals than are those involved in a single or a fewfunct ions.(4.5) Knowl edge of these i nterre1at i onsh ipsbetween minerals is increasing rapidly As thatknowledge expands in the field of mineral metabolism,many additional interrelationships will probably beelucidated

Animals obtain essential mineral nutrition fromtwo pri mary sources: (1) through natural feeds and,possibly, water, and (2) through supplementation offeeds and water Even though a 1arge port i on of therequired minerals may be provided by the vegetativeanimal feedstuffs, mineral supplementation is generally

a necessary practice for properly nourishing the animalsdue to dep 1et i on and i mba1ances of mi nera1sin thesoils, and consequently in plants.(6) The mineralcontents of a plant depend primarily on the plantspecies, the season, the abundance of the element in thesoil, the type of soil, and the conditions (pH,moisture, etc.) which affect the plant's ability toabsorb the mi nera1s.(7) Because of the many factorsaffecting this absorption, the mineral contents ofplants vary both within and among the species

Minerals in Animal Health 5

Furthermore, mineral requirements of plants are not thesame as for animals, so ratios of one mineral to another

and the Quantities of minerals, being proportioned for

different biological functions, may not meet the needs

of the animal when used in feeds The availability ofminerals in plants is also affected by phytic acid andoxalic acid found in the cellulosic cell membranes asopposed to cytoplasm It should be remembered that thepresence of a mineral in plant tissue used for feed doesnot guarantee its absorption into the animal's system

As stated by Underwood, "the evaluation of feeds andfeed supplements as sources of minerals depends not only

on what the feed contains, i.e the total content orconcentration as determined physio-chemically, but onhow much of the total mineral can be absorbed from thegut and used by the animal's cells and tissues."(8)

Before the development of isotopic techniques,absorption mechanisms of minerals were poorlyunderstood Without isotopes the primary difficulty forconfusion of mineral metabolism was due to absorption,excretion back into the gut, and reabsorption, often as

a standard cycle Conventional balance studies wereunable to indicate the net utilization of minerals.Absorption of mineral ions is dependent upon numerousfactors, including the levels of the elements ingested,the age of the animal, Ph of the intestinal contents andenvironment, the state of the animal with respect todeficiency or adequacy of the element, and the presence

of other antagonistic minerals or nutrients as well asseveral other conditions.(9) Earl ier investigators wereunable to consider these variables due to lack ofadequate technology, and thus their reports often lackedagreement With the use of isotopes it became easier tofollow the movement of trace elements through thebody (8)

In a practical sense, all animals are subject tomineral deficiencies These may be caused by: (a) asuboptimal amount of a specific mineral in the feed; (b)

6 The Roles of Amino Acid Chelates in Animal Nutrition

an imbalance of another mineral or nutrient includingcertain vitamins, amino acids and fats, any of whichcould decrease absorption; (c) any condition whichincreases the rate of passage of the minerals throughthe intestine, such as diarrhea; and (d) the presence of

a metabolic antagonist which causes the animal torequ ire a greater quant i ty of the needed element.(4)

Imbalances and deficiencies are not synonymousconditions, but either condition may lead to the other.The net result is less than optimum mineral nutritionfor the animal

The pathways for excretion and rates of excretion

of mineral elements vary Some are excreted almostentirely in the feces via the lower bowel; others areeliminated almost entirely in the urine, while stillothers are excreted through both pathways Certa inminerals are excreted in minute quantities through thesweat, and others are lost during the menstrual cycle.Integument losses from the animal's body may alsooccur.(4) Absorpt i on from the 1umen does not guaranteemineral usage in metabolism.(lO) In some cases mineralsare absorbed but later excreted in urine and feces asnon-metabolized wastes without ever being utilized inbiological processes

Chelation of minerals (a process by which a metalatom is sequestered) is employed in some feedingreg i mens in order to enhance the absorpt i on wi thoutregard to mineral metabolism Ametal chelate is formed

as a ring structure It is produced by attractionbetween the positive charges of certain polyvalentcations and any two or more sites of highelectronegative activity in a variety of chemicalcompounds known co11 ect i vel y as 1i gands Ache1ategenerally requires both an ionic and a covalent bond.The covalent bond in particular, known as a "coordinate"bond, occurs because of peculiarities in electron shells

of transition metals and the capacity of the donatingatom of the ligand to contribute two electrons at the

Minerals in Animal Health 7

same time The word "chelate" is taken from the Greekword chele meaning "claw," a fairly good descriptiveterm for the manner in which polyvalent cations are held

by the metal bi nd i ng agents or 1i gands.(12)

If any element is chelated by a ligand which willcarry the bonded mineral into the mucosal cell as anintact chelate, this chelate may indeed greatly enhance

merely releases an ion at the intestinal wall, this isfrequently no more efficient than use of metal saltsbecause once the ion is released, it is subject to the

mi nera1 absorpt ion 1i mi t i ng factors ment i oned above.Intact absorption is generally more efficient However,due to high stability constants, some chelates which are

absorbed, it occurs because the chelate prevents thechemical reaction of the element with other substances

in the stomach and intestines to form insoluble chemical

adsorption of the mineral onto insoluble colloids in the

absorption, it occurs because the ligand is capable ofeither releasing the cation to other metallic requiringcellular systems with subsequent metabolism of the freeligand, or the chelate is able to enter into a systemwhich requires both the metal and the ligand together

There are basically three types of chelates whichare recognized as being essential in biological systems:

The first group includes chelates which transport

properties of the ligand, but instead requires the use

of ligands with the chemical and physical propertieswhich will allow the metal to be absorbed, transported

in the bloodstream, and pass across cell membranes to

8 The Roles of Amino Acid Chelates in Animal Nutrition

such chelate is transferrin It chelates absorbed ironions which enter the blood and transfers them throughoutthe body The presence of transferri n in the blood,however, does not guarantee that th i s wi 11 be theultimate destination of absorbed or otherwiseadministered iron In the case of iron dextraninjections made to supplement inadequate body iron1eve1s , some of the iron i s i ncorporated intotransferrin, while the remainder is either eliminated inthe wastes or fixed in the connective tissues at thesite of injection.(13)

All amino acids are particularly effective metalbinding agents, and may be of primary importance in thetransport of minerals from the lumen into the mucosalcells as well as for storage of mineral elementsthroughout the an; rna1's body As part of ache1atemolecule these amino acid ligands do not functionbiologically as individual amino acids, but as uniquetransfer molecules

Ethylenediaminetetraacetic acid (EDTA) and similarsynthetic ligands may improve the availability of zincand certain other minerals for plants by protecting thecations from precipitating chemical reactions in thesoil EDTA and similar variants are effectively used inmedicine to hasten the excretion of lead and other heavymetals from animals poisoned by these metal ions.(l4)Generally speaking, however, EDTA chelates and similaranalogs, do not enhance mineral nutrition in animals.(ll)

The second group of chelates are those which areessential to physiology Many chelates exist in theanimal body in forms which allow the metal ion toperform its metabolic function(s) The chelated iron inhemoglobin and the chelated cobalt in vitamin 8-12 aresuch examples of this group of chelates Without itsiron moiety, the hemoglobin molecule could not transportoxygen On the other hand, if the i ron were notchelated, the hemoglobin could not effectively bind and

Minerals in Animal Health 9

release the oxygen for metabolic use.(15) Metals whichare chelated into enzyme systems and function as part of

a metalloenzyme are other examples of metabolicallyessential chelates.(16)

The third group of chelates consist of those whichinterfere with utilization of essential cations Manymetal chelates are probably formed "accidentally" andconsequently have no useful biologic value In Table 1

numerous enzyme systems are listed Many can bedeactivated or inhibited when the wrong metal forms achelate within the enzyme.(l7) One should note thevariety of cations required for the catalytic functions

of these enzymes Without them the enzymes will cease

to function This is a necessity which is frequentlyoverlooked by many who relegate mineral nutrition to itsstructural role in bones and teeth and are unaware ofthe importance of minerals as enzyme cofactors in basicmetabolism

Table 1 Enzymes Whi ch Are Infl uenced by Mi nera 1s (Modi fi ed from Schut te (lJ»)

Column I The trace element (or mineral element) constitutes the

prosthetic group.

Column II The trace element (or mineral element) is an active part of the

prosthetic group, or is incorporated into the enzyme itself Column III Elements with integrating function(s) that are not understood,

as yet El ements need not be speci fi c and may replace each other.

Column IV Facultative Activators.

Column V Inhibitors of enzyme activity.

ENZYME

Carbohydrases

Na,K,Li,Br, F,I Sr,Mg,Ca,Ba u-Amylase (animal) Cl

I,SO.,N0

10 The Roles of Amino Acid Chelates in Animal Nutrition

(Table 1 continued)

Esterases

Deoxyribonucleases Mg,Mn,(Ca) Ca,Ba

Alkaline phosphatase Zn,Co,Mn,Mg Ni , Fe++,Ca MgSH,CN

Minerals in Animal Health 11 (Table 1 continued)

12 The Roles of Amino Acid Chelates in Animal Nutrition

Oligometa- Mg,Mn,Co,Zn Ca,Ba,Al ,Ti, CN,F

Th,Pb,La,Ce, Nd,Sm,Y,Pr

Cu++, Pb++ (Mn) Hydrolases with varying

Minerals in Animal Health

14 The Roles of Amino Acid Chelates in Animal Nutrition

Minerals in Animal Health

NADPH dehydrogenase PO.

16 The Roles of Amino Acid Chelates in Animal Nutrition

PO., Mn PO., Mn, Co Mg

Minerals in Animal Health 17

In summary, there are many types of chelates, bothnatural and synthetic In addition to medicalfunctions, such as removal of certain isotopes orpoisonous metals from the animal's body, chelation canalso be used in the deactivation of bacteria throughmetal deprivation.(18) Nutritionally, amino acidchelates are used to enhance trace metal delivery to thebody.(19) For that to occur, the stab;1;ty constants ofthe chelating bonds must be compatible for intactabsorption while maintaining availability fordegradation at the sites of metal usage in the body.(20)

The molecular weight of the chelate must also be keptlow to promote intact absorpt ion (21)

The science of chelation as it relates to thenutrition of domestic animals is coming of age Theadvantage of using amino acids to chelate essentialminerals and render them more biologically available tothe animal offers greater possibilities to regulate theamount of a given metal ion at the cellular level thantechniques heretofore used