Social Rank and Physiological Traits of Dairy Cows as Influenced by Changing Group Membership ~ ,: C. W. ARAVE s and J. L. ALBRIGHT Department of Animal Sciences Purdue University West Lafayette, IN 47907
ABSTRACT
INTRODUCTION
Social behavior was observed in two groups of 17 cows during 13 wk to determine dominance rank. On the basis of dominance ranking during two biweekly intervals (wk 3 and 4, 7 and 8), a total of six cows was exchanged between groups (two during the first and four during the second exchange). The effect on milk yield, milk leucocyte concentration, and milk prolactin of dominance rank and introduction of "strange" cows into a group was studied. Dominance rank was greater for older, heavier, taller cows in a later stage of lactation. Fat-corrected-milk yield was greater for dominant cows but milk prolactin was lower. Dominance rank for cows moved to a new group did not change appreciably. Persistency of milk yield was associated negatively with dominance rank for five of six exchanged cows. 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. Neither dominance rank nor exchanging cows between groups had a significant effect on leucocyte concentrations in milk. Milk-prolactin concentrations were most highly correlated with dominance rank, stage of lactation, body weight, and height at withers.
Social dominance whereby an animal through threat, force, or mere presence causes a subordinate to yield space is known in all domesticated animals. This type of relationship was recorded for dairy cattle as early as 1853 (12). Additional commentary may be found in 1901 (4). Schjelderup-Ebb (20) first reported d o m i n a n c e - s u b o r d i n a n c e relationships or "peck-order" in poultry. Several studies have been made since further establishing this phen o m e n o n in that species (7, 25). Schein (18) in a herd of 87 Jersey and Red Sindhi cows on pasture found a straight line social order, i.e., cow 1 dominated all others; cow 2 dominated all except cow 1; cow 3 dominated all except cows 1 and 2. However, Beilharz and Mylrea (3) found several triangular or higher order relationships and were unable to assign a linear order but rather ranked them by the ratio of wins to total encounters. Social dominance rank has been correlated with age and weight (8, 19). Under confinement with competitive feeding conditions, the simultaneous removal of a high ranking Holstein heifer and the addition of a new one to a group of six often would cause a complete reversion of the social order. Dominance and weight were significant (P
ABSTRACT
INTRODUCTION
Social behavior was observed in two groups of 17 cows during 13 wk to determine dominance rank. On the basis of dominance ranking during two biweekly intervals (wk 3 and 4, 7 and 8), a total of six cows was exchanged between groups (two during the first and four during the second exchange). The effect on milk yield, milk leucocyte concentration, and milk prolactin of dominance rank and introduction of "strange" cows into a group was studied. Dominance rank was greater for older, heavier, taller cows in a later stage of lactation. Fat-corrected-milk yield was greater for dominant cows but milk prolactin was lower. Dominance rank for cows moved to a new group did not change appreciably. Persistency of milk yield was associated negatively with dominance rank for five of six exchanged cows. 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. Neither dominance rank nor exchanging cows between groups had a significant effect on leucocyte concentrations in milk. Milk-prolactin concentrations were most highly correlated with dominance rank, stage of lactation, body weight, and height at withers.
Social dominance whereby an animal through threat, force, or mere presence causes a subordinate to yield space is known in all domesticated animals. This type of relationship was recorded for dairy cattle as early as 1853 (12). Additional commentary may be found in 1901 (4). Schjelderup-Ebb (20) first reported d o m i n a n c e - s u b o r d i n a n c e relationships or "peck-order" in poultry. Several studies have been made since further establishing this phen o m e n o n in that species (7, 25). Schein (18) in a herd of 87 Jersey and Red Sindhi cows on pasture found a straight line social order, i.e., cow 1 dominated all others; cow 2 dominated all except cow 1; cow 3 dominated all except cows 1 and 2. However, Beilharz and Mylrea (3) found several triangular or higher order relationships and were unable to assign a linear order but rather ranked them by the ratio of wins to total encounters. Social dominance rank has been correlated with age and weight (8, 19). Under confinement with competitive feeding conditions, the simultaneous removal of a high ranking Holstein heifer and the addition of a new one to a group of six often would cause a complete reversion of the social order. Dominance and weight were significant (P
