Feather eating in layer pullets and its possible role in the aetiology of feather pecking damage

Abstract

Feather pecking and cannibalism remain serious welfare and economic problems in the egg industry. Previous studies have suggested a role for feather eating in the development of pecking damage, but no definite link has been shown. This study examined feather eating and its possible relationship with damaging pecking in pen-housed ISA Brown layer pullets. Collection and measurement of loose feathers in sample plots on pen floors (a bimodal distribution allowed characterisation of feathers as either `short' or `long'), and examination of faecal droppings (eaten feathers are not digested) were used to assess levels of feather eating. Feather eating was rarely observed directly, but the presence of feather material in a high proportion of droppings (up to 48%) suggested that the behaviour was common. Pecking damage occurred in 5 out of 12 pens and was related to feather eating as indicated by both depletion of feathers on pen floors and feather material in droppings. Short feathers were eaten preferentially, and an absence of short feathers was associated with an increase in partially eaten long feathers. The 4 pens exhibiting the highest levels of feather eating were those in which severe outbreaks of feather pecking and cannibalism occurred around the onset of lay. A second experiment, examining age-related changes in feather eating behaviour between 6 and 26 weeks of age, showed that feathers cast during a juvenile moult at 9–11 weeks were depleted by varying levels of feather eating over subsequent weeks. Numbers of short feathers available on pen floors decreased with age while numbers of partially eaten feathers increased, as did proportions of droppings containing feathers. Levels of feather eating were lower than in the first experiment, and there was no pecking damage. It is concluded that once feather eating has become established, a low availability of preferred short feathers on pen floors may cause feather eating and pecking to be redirected to other birds. High levels of feather eating by growing birds (perhaps above a threshold level) may be associated with feather pecking and cannibalism around the onset of lay.