BB/O(ttawa)K(arlsburg) rats: features of a subline of diabetes-prone BB rats.

The development of incidence and age at onset of diabetes as well as the breeding performance and other phenotypic traits of the BB/O(ttawa)K(arlsburg) rat subline are assessed in relation to degree of inbreeding and mating system. With increasing inbreeding body weight decreased and striking changes were observed in incidence and age at onset of diabetes, whereas breeding performance remained largely unchanged. Because the rats were free of most of the relevant pathogens and the transfer of BB rats into a germ-poor environment with the aid of wet hysterectomy had no effect on incidence and age at onset of diabetes, a segregation of diabetogenic genes rather than an influence of environmental factors is supposed to be responsible for both the varying traits.