DIURNAL AND INDIVIDUAL VARIATION IN BEHAVIOR OF RESTRICTED-FED BROILER BREEDERS

Individually marked immature female broiler breeders were kept in groups of 12 and 11 birds in two pens, with lights on from 05:00 to 19:00 h, ad libitum access to water, and a restricted food ration provided daily at 08:30 h according to commercial guidelines, which was eaten in 4-16 min. At 18 and 19 weeks of age, systematic observations of each bird's behaviour during the day showed that, in both pens, activities that took up most time were standing, walking and those directed at floor litter, drinking dispenser and empty feeding trough. Greatest variation between birds was shown in stereotyped pecking at the drinker, empty feeder and pen walls, and in resting. Resting and preening were most evident soon after lights on, standing and walking just before feeding time, stereotyped pecking occurred in the hours after feeding, and litter-directed activity was more consistent throughout the day. Different birds tended to 'specialize' in stereotyped pecking at either the drinker or feeder, and in later observations when one or both of these were removed, they did not redirect their pecking towards another object, but spent more time in non-stereotyped activities. Total times spent in stereotyped pecking by individual birds were correlated negatively (P = 0.05 with both pens combined) with their plasma corticosterone concentrations at the end of the 2 weeks of observations, but not with other (putative) indices of stress and fearfulness or with body weight. Thus, birds showing more stereotyped activity tended to show less stress as indicated by plasma corticosterone level, which supports the proposal that such behaviour has de-arousing consequences.