81 

 mg/kg) . For this experiment with sheep, organic sources of Zn 

 were of equal availability or more available than the most 

 available inorganic source and may be metabolized differently 

 in some tissues. 



Experiment 3 was conducted to compare toxicity of CuLys 

 and CuS0 4 when supplemented at concentrations that would cause 

 a chronic toxicity to sheep. Three crossbred wethers and 1 

 crossbred ewe averaging 46 kg were randomly assigned to 250 mg 

 of supplemental Cu from either CuLys or CuS0 4 . Lambs were fed 

 the treatment diets for 4-11 wks following a 7 d adjustment 

 period. Blood samples were taken on d 1 before treatment 

 began and biweekly thereafter. Serum and blood samples were 

 analyzed for CK, GGT, AST, and heinz bodies. Sections of 

 liver and kidney were excised and autopsied, and together with 

 serum and diet analyzed for Cu and Zn . The liver and kidneys 

 of one of the CuS0 4 treated sheep could not tolerate the high 

 dietary Cu as did the others, resulting in a rapid elevation 

 of serum Cu . The other CuS0 4 treated sheep was apparently 

 never affected by Cu excess. Myodegradation was present in 

 one animal from each treatment prior to death probably caused 

 by excess Cu in blood and muscle. The use of high Cu 

 supplementation in sheep and the development of toxicity from 

 this limited number of animals was not dependant on source 

 used. 



Experiment 4 was divided into two phases . Phase 1 was 

 conducted to compare bioavailability of different sources of 



