EFFECT OF BREED, INTAKE, AND CARCASS COMPOSITION ON THE STATUS OF SEVERAL MACRO AND TRACE MINERALS OF ADULT BEEF-CATTLE

The objective was to determine the association between breed, intake, and carcass composition and the status of liver Cu, Zn, and Fe, and se rum Cu, Zn, Ca, and Mg of 118 mature cows representing nine breeds of cattle. Breeds used were Angus, Braunvieh, Charolais, Gelbvieh, Herefo rd, Limousin, Red Poll, Pinzgauer, and Simmental. The cows were fed on e of four levels of DMI: 58, 76, 93, and 111 g of DMI . wt(-.75). d(-1 ). A ground alfalfa, corn, and corn silage diet was fed for up to 5 yr . There was no relationship between liver and serum concentrations of Cu, a negative correlation (P <.05) existed between liver and serum co ncentrations of Zn and a positive correlation (P <.01) existed between liver concentrations of Cu and Zn. Concentrations of serum Ca were po sitively correlated (Cu and Zn, P <.01; Mg, P <.05) with serum concent rations of Cu, Zn, and Mg, but negatively correlated (P <.01) with liv er Fe. Liver Cu was higher (P <.05) for the Limousin breed than all ot hers, except Angus. Liver Zn concentrations were higher(P <.05) for Li mousin than for Pinzgauer, but no other breed differences were observe d. Liver Cu concentration was not affected by daily intake, but liver Zn concentration increased (P <.05) with increased daily intake. Liver Fe concentration decreased (P <.01) in a curvilinear manner with incr eased daily intake. No breed differences in serum concentrations of Cu or Zn were observed. Serum Ca concentrations were higher (P <.05) for Angus, Red Poll, and Limousin than for Simmental, and Red Poll had hi gher (P <.05) concentrations of serum Ca than for Braunvieh. Serum Mg concentrations (P <.05) were higher for Angus than for Hereford. Serum Zn and Ca were not affected by daily intake, and serum Cu was a quadr atic function of intake (P <.05). There was a stronger association of carcass lipid (percentage) with liver and serum Cu concentrations (P < .01) than existed between carcass protein (percentage) and liver and s erum Cu concentrations (P <.05). These results indicate that breed dif ferences may exist in Cu metabolism. Liver Cu and serum Cu concentrati ons were not related, carcass composition was associated with Cu conce ntrations in both liver and serum, liver Cu and Zn were,positively cor related, increased intake was associated with increased liver Zn, decr eased liver Fe, and no change in liver Cu.