Cattle and sheep are exposed to lead and zinc when these poisons are in the

Cattle and sheep are exposed to lead and zinc when these poisons are in the grass/soil.
Cattle and sheep graze on the grass, and thus they intake these minerals, such as lead and zinc when they come in contact with grass or earth they may eat along with grass. Thus they are exposed to them via eating. 

Apicture would .

Ithink you should go back and learn in school rather then here asking questions