A cytogenetic survey of five breeds of cattle from Brazil.

One-hundred-and-thirty-nine animals from five breeds of cattle were studied cytogenetically. Three types of karyotype abnormalities were detected, two of them structural, t(1; 29) and ins(16), and one numerical (60,XY/61,XY + F). The first two, found in the Charolais race, presented familial recurrences; the last one, observed in the Norman breed, was sporadic. Pedigree studies showed that ins(16), an aberration not previously described in cattle, segregated in the ratio of 5 carriers to 10 normals. t(1; 29) occurred in mother and daughter. A variant of constitutive heterochromatin also presented familial recurrence in the Charolais breed.