The main advantages of battery cages for laying hens over alternative husbandry systems are (1) increased hygiene resulting in a much lower incidence of diseases in which the infectious agent is spread through the droppings, (2) small group size resulting in a low incidence of social friction, (3) ease of management, (4) absence of litter problems, (5) better working conditions, and (6) a much lower cost of production. The disadvantages are (1) lack of physical and psychological space for the hens, (2) lack of exercise resulting in a higher incidence of metabolic disorders, (3) lack of nesting opportunities resulting in severe frustration for many birds each time an egg is laid, (4) lack of dust bathing opportunities which, although not a severe disadvantage, should still be charged to cages, (5) lack of other behavioural opportunities which again seem not to be a severe disadvantage and which await further elucidation, and (6) a higher incidence of foot lesions.
