Zinc oxide administered at a pharmacological level
improves performance and reduces the incidence of diarrhea/
colitis in the post-weaned piglets (Mavromichalis et
al., 2000). However, the high rate of its excretion into the
environment has let to interest in the potential of organic
minerals. Only 2% to 10% is recovered in the urine, while
the remainder is lost in the feces (Hambidge et al., 1986).
Supplements to the diet containing copper significantly
increased the concentration of sulfides in the supernatant,
creating a condition that is toxic to phototrophic bacteria.
In contrast, a decrease in sulfide concentration resulting
from the addition of dietary zinc favored phototrophic
bacteria. Since pig slurry is therefore high in copper and
zinc, these can accumulate in the topsoil and in crops.
Care must be taken when grazing sheep due to their