Evaluation of genetic divergence among lines of laying hens using cluster analysis

Barbosa, LRegazzi, AJLopes, PSBreda, FCSarmento, JLRTorres, RATorres Filho, RA

Cluster analysis was used to investigate the genetic divergence among five lines of laying hens. The following traits were evaluated: body weight at 40, 48 and 56 weeks of age; egg weight at 40, 44, 52 and 60 weeks of age; and laying rate from 40 to 60 weeks of age. Three groups were formed when data were analyzed by the single-linkage hierarchical method using squared Mahalanobis distance (D²) as dissimilarity measures: one group comprised lines 3 and 5, the second group line 1, and the third group comprised lines 2 and 4. Using Tocher's optimization method, only two groups were formed: one group comprised lines 3, 5 and 1, and the second comprised lines 2 and 4. This evidences the disagreement between the methods over the evaluation of genetic divergence. The trait that contributed mostly to the genetic divergence was body weight at 48 weeks of age.

1. single linkage
2. Laying hens
3. Tocher's optimization method
4. Mahalanobis distance