COMPARATIVE ASPECTS OF BEHAVIORAL ACTIVITIES OF BEEF-COWS BEFORE AND AFTER INTRODUCING A STRANGER AT NIGHT

Two groups of dry-lot feeding beef cows comprising 7 residents and a s tranger (Groups A and B) were used to examine differences in social an d maintenance behaviours before and after introducing the stranger at night, i.e. after dark when most resident animals were recumbent while resting or ruminating and there was less social activity. Agonistic a nd social licking interactions and incidents of eating, lying, standin g and locomotion of each animal in each group were recorded during the daytime. Body weight change for each cow in the groups after introduc tion was also estimated. In Group A, there was little change in the fr equencies of agonistic and social licking behaviours during the observ ation period. In Group B, there was more than a 2-fold increase in the frequency of agonistic behaviour following the introduction, though s ocial licking changed little over the period. In each group, a relativ ely higher frequency of aggressive behaviour initiated and received by each stranger occurred on the 1st to 2nd day after introduction, whic h thereafter tended to decrease until the 7th day. The stranger in Gro up A significantly received more frequent aggression from residents th an a stranger in Group B (P < 0.05). The strange cow in each group spe nt less time eating and more time in locomotion than residents. A sign ificant negative correlation between eating time and relative body wei ght change in Group A (P < 0.05) suggested that a greater weight reduc tion in the strange cow after introduction is mainly associated with h er less eating time.