Figure 2.

Number of hens of each of the 4 strains found in the 3 tiers of the aviary enclosure during the PRE period before hens had any access to litter (2A); the IMM period when hens first gained access to litter (2B); and the ACC period after 3 wk of access to litter (2C). Data are presented separately for MORNING, MIDDAY, and EVENING. All parameters are expressed as mean bird counts ± standard deviation. Different superscripts indicate differences (P < 0.05) among different strains in that tier level at that time of day.