Social Relationship of Dairy Cows in a Feed Lot

Abstract

Twenty-four Holstein cows, divided into two equal groups, were observed in a feed lot for five consecutive days, eight hours each day. Each group was observed for a second five-day period approximately one month later. Three observers recorded the social interactions of the cows in the lot. Size, milk production, ingestive and eliminative behavior, and acts of servitude were tabulated for each cow. Agonistic behavior was recorded in the following categories; contact, bunting, forceful, nonforceful, and pushing. From the 3,463 contests observed, dominance values were computed by a least-squares procedure for each of the five categories. A social order was established within groups, combining all observations in all categories. Estimates of repeatability for dominance value were .97 from day to day in the same week, and .95 from day to day in different weeks. Partial correlation coefficients calculated indicated the highest relationship observed was between dominance value and weight. There appeared to be no correlation between dominance value and milk production. The data indicated the existence of at least three social structures within an established herd of dairy cattle - a milking order, a leadership-followership pattern, and a dominance hierarchy. The dominance hierarchy appeared to remain stable over a period of time. If animals are given sufficient opportunity for social contact, one day's observations can determine this social order.