Evaluation of an enrichment
device for caged laying hens
A.A. Taylor, G.I. Hurnik,
and J.F. Hurnik
University of Guelph,
Guelph, Canada
The static, low complexity
environment of the modern battery cage has been linked to behaviours believed
to indicate that the quality of life of caged laying hens is compromised.
Such behaviours include increased aggression, stereotyped featherpecking,
and even cannibalism. The goals of enrichment, therefore, are to
relieve occupational deprivation in the hopes of preventing the development
of such behaviours, and to provide a target object other than
cagemates for their expression.
Enrichment devices must not only be safe and hygienic, but also relevant
to those motivational systems thought to be deprived in the hens' environment
and, in order to maintain bird interest over the long term, be variable
in their response to bird interaction. A commercially available enrichment
device for laying hens claims to result in significant improvements in
egg production, egg weight, and mortality rates, as well as a decrease
aggressive behaviour among caged laying hens. In addition to examining
production effects, the current study intended to examine behavioural patterns
of device use, and to assess its usefulness in relieving the behavioural
deprivation of
caged housing.
The device was distributed to one half (320 birds) of the birds participating
in a parent project looking at
interactions between
5 strains of commercial White Leghorns and 4 diets, balanced for strain
and diet. The hens were housed in pairs in battery cages providing 575
cm2 per bird, and fed ad libitum. Production data was collected biweekly.
Behavioural data were collected from a focal group of 4 cages (8 birds),
videotaped for 14 hours during Weeks 18, 22, 26, 30, 38, 48, and 54 of
age. The productivity of experimental and control birds did not differ;
control hens laid, on average, 259 eggs through their laying cycle, and
experimental hens laid, on average, 258. Only 7 control and 8
experimental hens died
between Weeks 18-63 (2.19% and 2.5%, respectively, P > 0.05). Hen
use of the device was relatively low initially, rising from 0.357 to 0.497
and then dropping to 0.232 interactions per hen-hour during the first five
months of the study (Weeks 18-38). This suggests a typical habituation
effect, although the duration of the habituation phase was much longer
than reported elsewhere. After Week 38, the frequency of hen-device
interactions increased dramatically, reaching almost 2 interactions per
hen- hour. The abruptness of the increase suggests a specific change in
the birds' motivational
relationship with the device, perhaps as a result of the effects of longer-term
exposure to the barren cage environment. If this is the case, then
the device may help to alleviate problems with featherpecking or cannibalism
among caged laying hens. However, this welfare benefit would be experienced
primarily by the cage-mates who would be spared as target objects.