A highly significant positive correlation between duration of shackling period and TI duration was found in
our experiment, which indicated an increased level of
fear in shackled broilers that grew with the extension
of the shackling period. Similarly, Zulkifli et al. (2000)
observed a prolonged TI duration in response of broiler
chicks to hanging in an inverted position and claimed
augmented fearfulness. Furthermore, Jones (1989, 1992),
Scott et al. (1998), and many others also report increased
TI duration in association with rough handling in domestic poultry and related these changes to the fear level of
birds. In addition, even after 30-s shackling of broilers,
the number of attempts to induce TI was decreased in