[Population structure analysis in sheep without wool in the conservation nucleus]

ABSTRACT This study evaluated the population structure of sheep without wool from the conservation nucleus in Ceará State, Brazil. Population parameters were estimated on genealogical records of Santa Ines (SI), Somali (SO,) and Morada Nova (MN) breeds, that were born between 2001 and 2014. The following estimates were obtained: number of complete generation equivalents (GCE), generation intervals (IEG), number of founders (Nf), effective number of founders (fe), effective number of ancestors (fa), inbreeding coefficient (F), and genetic contribution index (ICG). Average GCE was 1.82, 2.78, and 1.52 for SI, SO, and MN respectively. Mean IEG was similar between breeds, 3.67 years. The Nf was 225, 194, and 153 for SI, SO, and MN respectively. The fe/fa ratios were different to 1, which is an indication of genetic bottleneck, mainly for SO. The average inbreeding coefficients were 1.81%, 0.78%, and 0.78% for SI, SO, and MN respectively. The ICG was 3.32, 5.38, and 2.87 for SI, SO, and MN respectively. Estimated population parameters indicate that part of the genetics of these breeds was lost, mainly in Somalis.