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conditions of livestock. Although there is considerable disparity among differ-
ent social and professional groups, it appears that during the last three decades
there has been a definite shift in the direction of greater concern in matters of
pain and suffering of farm animals and a tendency to favor protectionist legisla-
tion (
Mench, 2008; Mench et al., 2011; Millman et al.,2010
). Public pressure
for increasing the well-being of chickens in Western Europe led to codes of
recommendations for “humane” husbandry and, in the extreme, legislation was
enacted phasing out the use of conventional cages for layers starting in 2012 in
the European Union (
CEC, 1999
) and some states of the United States
(
California proposition 2, 2008
). It is of special interest that the prohibition of
caging hens occurred even though cages have been shown to have some advan-
tages over alternative housing systems (
Appleby et al., 1992, p. 207; de Wit,
1992
;
Lay et al. 2011
;
Mench et al., 2011
), for example, cannibalism is more
common in non-cage systems than in dimly lit cage houses.
Behavioral problems exist not only among chickens kept in cages but also in
alternative systems (
Appleby and Hughes, 1991; Craig and Adams, 1984; Lay
et al., 2011; Mench, 1992; Siegel, 1989
). Recent reviews examined the future of
the poultry industry and included issues related to politics, housing, ethical, and
well-being concerns (
Hester, 2005; Lay et al., 2011; Mench, 2008; Mench et al.,
2011; Millman et al., 2010; Newberry and Tarazona, 2011
) but perhaps the
most striking conclusion given this move away from cages was that of Lay and
associates (
Lay et al.,2011
) who concluded that there is no one clear solution to
the housing issue and that no housing system is ideal from a hen-welfare per-
spective. In floor pens and outdoor systems, hens are exposed to litter and soil,
providing a greater opportunity for disease and parasites with similar conse-
quences from adding environmental complexity. Further, the more complex the
system, the more difficult it is to manage and with larger group sizes, disease is
more likely to spread. Additionally, increasing the space per hen increases
incidence of cannibalism and smothering and introduces difficulties in terms of
disease and pest control while adding environmental complexity increases unde-
sirable behaviors that are detrimental to welfare (
Lay et al.,2011
).
A promising resolution was suggested by Muir and associates (
Muir, 1996,
2003; Muir and Cheng, 2004
) and others (
Cheng, 2007, 2010; Laible, 2009;
Lay et al., 2011; Newman, 1994; Cheng and Muir, 2005
) who concluded that
selective breeding for desired traits may help to improve welfare in domesti-
cated settings and decrease or eliminate instances of undesirable behaviors
in cages or alternative housing systems. The focus of this chapter is toward
changing the nature rather than the nurture of chickens to improve welfare in
domestic environments.
ASSESSMENT OF WELFARE
The words welfare and well-being are widely used but connotations
vary. Dictionary definitions reflect an anthropomorphic viewpoint, e.g.,
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