Effects of the ionophore anticoccidial semduramicin on broiler breeders

Three experiments were conducted to assess the effects on broiler breeders of contamination of feed with the ionophore anticoccidial semduramicin. In Experiment 1, individually caged females received 0,12.5, or 25 mg/kg diet for 3 wk from 48 to 50 wk of age. In Experiment 2, males and females in flo or pens received 0, 12.5, or 25 mg/kg diet for 3 wk from 63 to 65 wk of age . In Experiment 3, individually caged males and females received 0, 3, 6, o r 25 mg/kg diet for 1 wk at 31 Wk Of age and were mated by artificial insem ination. There was a dose-related decrease in cumulative egg production and percentage shell in Experiment 1 after more than 1 wk exposure, but these effects were not observed in the other experiments. There was a decrease in cumulative fertile hatchability and a dose-related decrease after 3 wk exp osure due to an increase in early embryonic mortality in Experiment 2, but these changes were not observed during the 1-wk exposure in Experiment 3. T he data show that adverse effects of semduramicin require greater than 1 wk of exposure to be evident.