Social aggregations in cattle. I. Segregation by breed in free-ranging herds.

Social aggregations of free-ranging cattle were studied in the Sonoran Desert of Mexico. Cows reared with animals of their own breed in isolation from other breeds maintained segregated social groups. Cows raised together in a mixed herd containing other breeds allied themselves with herd-mates regardless of breed. Cattle of the mixed herd stayed with their peers rather than rejoining their mothers when they were placed together. Although there were breed differences in group cohesiveness among cattle raised with their own breed, social aggregations appeared to be more dependent on social history than on genetic affiliation and shared phenotype.