24 

 the daily supplemental Zn the diets were formulated to contain 

 200 mg Zn/kg diet. Animals were fed individually via Calan 

 gates 1.8 kg of a corn-based concentrate into which the three 

 different Zn sources were mixed. Bermuda grass hay was 

 offered ad libitum. Zinc content (Dry matter basis, DMB) was 

 19.6 mg/kg in hay and ranged from 20 to 26 mg/kg in the 

 control diet (Table 3-1) . The diet was formulated to be 

 adequate in protein, energy, vitamins, and minerals for this 

 class of cattle (NRC, 1984). Heifers were given supplemental 

 Zn for 4 wks, depleted (not supplemented) the following 4 wks 

 and then supplemented for 4 wks . Protocol for animal care had 

 been approved by the University of Florida's Institutional 

 Animal Care and Use Committee. Weights were obtained monthly 



TABLE 3-1. Composition of concentrate diet 

 offered to cattle (as fed) a . 



Ingredient Percentage 



Corn 84.07 



Soybean meal (44% CP) 14.3 



Dicalcium phosphate 1.05 



Salt b .29 



Trace mineral mix .26 



Vitamins A and D 3 d .03 



a Zn analysis biweekly indicated means of 248, 251 and 



256 mg/kg for ZnMet, ZnS0 4 and ZnO, respectively. Hay 



intake ranged from 2 to 5 kg (as-fed) . 



b Provided 2.1 g of NaCl per kilogram of diet. 



r Provided .24 mg of I (KI), .28 mg of Co (CoCOJ, 82 mg 



of Fe (FeS0 4 ), 38 mg of Cu (CuCl), 48 mg of Mn "(MnS0 4 ) 



and no Zn per kg of diet . 



a Provided 5,000 IU of vitamin A and 500 IU of vitamin 



D, per kg of diet . 



