Agonistic and Nonagonistic Behaviors of Pullets of Dissimilar Strains of White Leghorns When Kept Separately and Intermingled ,

Agonistic and nonagonistic behaviors were compared for pullets of two white Leghorn strains. One strain had been selected for part-year egg production; the other was the unselected control from which the selected strain was derived. There were two experiments in which the strains were kept separately and intermingled in laying-house floor pens. The selected strain had social dominance over the control at 5 months (before sexual maturity), but that dominance had diminished or disappeared when strangers of the two strains were placed together at 17 months. Nevertheless, because of social inertia, selected strain pullets maintained undiminished dominance over control pullets for the entire laying year when they were kept together from housing time onward. Selected strain females had more aggressive acts, more feeding activity, and spent less time resting than control females in both separated- and intermingled-strain housing environments. When pullets of the two strains were kept together, the relative frequencies of their agonistic behaviors were changed, but nonagonistic activities were not altered. Pullets had increased frequencies of pecking and fighting, but not of chases and threats, when they were hungry and feeding. Pullets with higher social status had more feeding activity when feed was constantly available, but that was not apparent when all were hungry and feeding. Preening activity increased as pullets aged.