Dorset, Finnsheep, Composite I (50% Finnsheep, 25% Dorset, and 25% Rambouillet), and Composite II (50% Finnsheep, 25% Suffolk, and 25% Targhee) sheep were evaluated under three different twice-a-year breeding schedules. Data were obtained on 9419 lambs produced from 2334 ewes and 257 rams for five years. Composite ewes had the highest conception rates and litter sizes along with the heaviest litters. Animals bred in schedule I had the heaviest and largest litters, and highest conception rate. Twice-a-year lambing programs must use the correct breeding schedule and using composite breeds can...