Arave, C. W., Albright, J. L. 1976. Social rank and physiological traits of dairy cows as influenced bychanging group membership. Journal of Dairy Science 59, 974-981.

Since the average persistency of milk yield for all cows dropped 5% from wk 7 to wk 8, it appears exchange of cows between groups affected both exchanged and nonexchanged cows in a random manner [p. 974].