19 

 effective growth promotant for weanling pigs. In sheep 

 studies (Pott et al . , 1992), Cu from CuCl 2 , CuS0 4 , CuC0 3 , and 

 Cu acetate sources were of similar bioavailability. Nockels 

 et al . (1993) suggest that CuLys is better retained than that 

 of CuS0 4 in stressed calves and that significant changes 

 occurred in Cu and Zn balance with supplementation and stress. 

 In a bioavailability study using growing cattle, Kegley 

 and Spears (1993) suggested that Cu from CuLys was of similar 

 bioavailability to that from CuS0 4 but these were higher than 

 CuO. Kincaid et al . (1986) using a diet high in Mo and S 

 found Cu proteinate to increase Cu status (plasma and liver 

 Cu) more readily than CuS0 4 suggesting the Cu proteinate to be 

 less affected by high Mo. In two separate studies, however, 

 Wittenberg et al . (1990) showed no difference between Cu 

 proteinate and CuS0 4 as to their effect on the Cu status of Cu 

 depleted steers fed diets high in Mo. Ward et al . (1993) 

 supplemented CuLys or CuS0 4 to growing steers fed a diet with 

 or without supplemental Mo and S. They found no difference 

 between CuLys and CuS0 4 bioavailability using growth rate, 

 feed intake, feed efficiency, plasma Cu, ceruloplasmin 

 activity, and immune response as indicators of Cu status. 



Bioavailability of Other Trace Mineral Complexes 



Ward et al . (1992) suggested that a mixture of Zn, Mn, Cu 

 and Co in amino acid complexed forms may stimulate feed intake 

 and growth during the initial stress period of feedlot steers 



