CHAPTER 4 



RELATIVE BIOAVAILABILITY OF TWO ORGANIC 



AND TWO INORGANIC ZINC SOURCES 



FED TO SHEEP 



Introduction 



The use of amino acid complex minerals in mineral 

 supplements compared to inorganic forms is still 

 controversial . Limited research has been done concerning the 

 biological availability of organic and inorganic mineral 

 sources. In a trial to test bioavailability, Spears (1989) 

 found that when a deficient diet was fed, apparent absorption 

 of Zn from Zn methionine (ZnMet) or ZnO forms was similar, but 

 Zn retention increased with ZnMet, suggesting different 

 metabolism following absorption. 



The majority of bioavailable Zn when supplemented in 

 relatively high levels is stored in body organs such as liver, 

 kidney and pancreas with minor storage in bone, muscle and 

 skin (Ott et al . , 1966) . Blood plasma serves as an immediate 

 source of stored Zn . Dietary Zn also stimulates production of 

 the protein metallothionein (MT) in some tissues (Blalock et 

 al. , 1988) . 



The objectives of this study were to compare 

 bioavailability of two organic and two inorganic Zn sources in 



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