Frequency and distribution of rob (1;29) in three Portuguese cattle breeds.

Representative samples of Portuguese cattle from Barrosã, Maronesa, and Mirandesa breeds underwent cytogenetic investigation. Banding showed that 134 (65.0%) Barrosas, 74 (40.2%) Maronesas and 4 (1.6%) Mirandesas carried rob (1;29). The frequency of this translocation in the three breeds (39% in Barrosas, 23% in Maronesas, and 1% in Mirandesas) was in a genetic Hardy-Weinberg equilibrium for the three karyological forms (2n = 60, 2n = 59 and 2n = 58), strongly supporting the hypothesis for an ancient origin of this translocation and the hypothesis of the origin of Maronesas from Barrosã and Mirandesa cross-breeding.