Crossbred Ewes of Finnsheep, Dorset and Rambouillet Breeding When Mated to Purebred or Crossbred Rams

Reproductive performance and body weights of four and five-year old crossbred ewes representing five combinations of Finnsheep (F), Dorset (D) and Rambouillet (R) breeding were evaluated when lambing in the summer Oune-July, 1976). The five breed combinations represented were 1f2D, 1f2R; %D, %R; %F, 1f2D, %R; %F, %D, 1f2Rand %F, 3f4R. Breeding effectiveness of purebred and crossbred rams of Hampshire and Suffolk breeding was also compared when mated to these ewes. Body weights taken before both breeding and lambing indicated that substitution of either Dorset or Finnsheep breeding for Rambouillet breeding resulted in decreased body weight but that less ofa decrease resulted from the Finnsheep substitution than from the Dorset substitution. Results of the summer lambing were quite favorable with the entire flock averaging 1.5 lambs born per ewe exposed. Fertility did not differ greatly among the five crossbred ewe groups with at least 93 percent of the ewes in each crossbred group lambing. The %-Finnsheep ewes had a higher lambing rate than did ewes of only Dorset and Rambouillet breeding (1.64 vs. 1.47). This resulted in %-Finnsheep ewes giving birth to 22 more lambs per 100 ewes exposed than crossbred ewes of only Dorset and Rambouillet breeding. With January-February mating, reproductive performance of ewes when mated to either crossbred or purebred rams was virtually the same whether measured by fertility, lambs born per ewe lambing or lambs born per ewe exposed. These results are in contrast to previous findings involving two years of May-June mating where these same ewes when mated to crossbred rams