CHAPTER 5 



DEVELOPMENT OF ACUTE COPPER POISONING IN 



SHEEP FED ORGANIC OR INORGANIC COPPER 



Introduction 



It is well known that sheep are one of the most sensitive 

 animals to Cu toxicosis. The exact biochemical etiology of 

 the Cu toxicity is not well known. Saylor et al . (1980) 

 suggested that because of the low capability for intestinal 

 metallothionein (MT) synthesis by sheep, the Cu absorption 

 process was not as well regulated as that of other species. 

 Furthermore, it is well known that MT in the tissues of sheep 

 do not respond to increased inorganic Cu levels (Saylor et 

 al., 1980; Peterson and Mercer, 1988). 



The toxicity, however, can be either chronic or acute 

 depending on the dosage and time of exposure to the mineral. 

 Sheep that are supplemented with relatively high doses of 

 inorganic Cu during an extended period of time may die of 

 hemolytic crisis. During the first phase of the increased 

 dose (> 26 mg/d) , the liver and other tissues of the sheep 

 accumulate Cu . This phase may last from 6 to 10 weeks or 

 longer. After the tissues are saturated with Cu, the blood 

 levels of Cu begin to rise, the animals loose their appetite, 

 develop an excessive thirst and become jaundiced. During this 



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