Matrilinear social dominance and spatial relationships among Angus and Hereford cows.

Two groups of Angus and Hereford cow families on summer pastures were observed to determine the effects of kinship and breed on social dominance and spacing relationships among individuals within groups. Each group was composed of 20 cows and contained two granddam-dam-daughter families and two dam-daughter families of each breed. Herefords tended to weigh more (P less than .10) than Angus; 518 (SD = 114) and 467 (SD = 92) kg, respectively. However, Angus were socially dominant (P less than .01) to Herefords, with 51.9 (SD = 20.1) and 33.4 (SD = 15.9) mean dominance values for cows of the respective breeds. In no case was a Hereford cow determined to be dominant to an older Angus cow. Within families of both breeds, dams and granddams were always dominant to their progeny. Relative distances among cows were determined on 30 occasions over a 2-mo period of time. Based on nearest neighbor frequency, there was a tendency for members of families to aggregate, but in general family explained only a slight to moderate amount of variation in spacing characteristics. Breed affected mean distance to all cows (P less than .01), distance to group center (P less than .05), distance to same breed group center (P less than .01), distance to opposite breed group center (P less than .05) and mean distance to all cows of the same breed (P less than .01), but breed did not affect mean distance to all cows of the opposite breed. Distances for Angus were less than those for Herefords for each of the significantly affected spacing characteristics.(ABSTRACT TRUNCATED AT 250 WORDS)