Production-related traits of layers reared in different sized flocks: the concept of problematic intermediate group sizes

Laying hens were reared from 1 d of age in four replicates each of four different group sizes: 15, 30, 60, and 120 birds. To maintain stocking density at a constant 5 birds/m2, they were housed in litter floor pens of 3, 6, 12, and 24 m2, respectively. The allocation of feeder space, drinker nipples, and perch space was also constant per bird, irrespective of group size, as was the arrangement of resources in the pens. Birds were individually...