Modifications to laying cages suggested by previous trials at Edinburgh include provision of a perch, a nest box and a dust bath, and increased area and height compared to conventional cages; the effects of combining these features is now described. Medium-weight hybrids were housed as groups of 4 in 48 cages of 4 types:

• control cages (C);

• experimental cages with nest box lined with litter (L);

• experimental cages with nest box lined with artificial turf (A);

• experimental cages with nest box lined with plastic grid (P).

In sub-treatments A1 and P1, eggs were prevented from rolling away for the first 6 weeks of lay, by blocking the rollaway slot. In sub-treatments A2 and P2, eggs rolled away from the beginning of lay.