RESUMEN
Data were collected by the Virgin Islands Beef Cattle Improvement Program and the Virgin Islands Agricultural Experiment Station staff to establish the breed structure of the Senepol cattle. Data for the analysis were limited to the two Virgin Islands Senepol breeders with the most complete and largest set of records, representing approximately 65% of the entire Senepol population. Inbreeding (F) and coancestry relationship coefficients (rAB) and the theoretical inbreeding (FT) were determined from each data set and for the combined data from both farms, for each year, ranging from 1947 to 1984 for Annaly Farms, and from 1967 to 1984 for Castle Nugent Farm. The data sets for both farms were examined for the possibility of separation into families. Actual F within the Senepol population was relatively low, averaging less than 1.00%. Some separation into families occurred within Annaly Farms' cattle. The F and FT decreased (1.6 to 0.7% and 1.0 to 0.2%, respectively) as population numbers increased. The low F was accomplished through the breeding programs and exchanges of animals between farms on the island.