The average Cu and Zn balances over the experimental period are presented in Table 2. Feed intake was increased for diets with the organic mineral supplement (p < 0.05) and, as a tendency, for those with the MOS supplement (p < 0.10). No treatment effect was observed on daily body weight gain but the final body weight tended to be greater in pigs fed organic mineral supplement (p < 0.08) or its combination with MOS supplement (Mineral source × MOS, p < 0.10). Daily absorption and retention of Cu and Zn were greater in pigs given the organic mineral supplement (p < 0.05) or the MOS supplement (p < 0.05). Excretion of Cu in faeces tended to be reduced (p < 0.09) in organic mineral treatments. This reduction was associated with increased apparent digestibility and retained/ingested ratio of Cu (p < 0.01). Urinary excretion of Cu tended to increase in MOS supplemented treatments (p < 0.06). Neither the mineral source nor the MOS
supplement had any significant effect on the apparent digestibility or retained/ingested ratio of Zn but urinary excretion of Zn was greater with organic mineral supplementation(p < 0.05).