The particle size of the ESBM did not affect gizzard
relative weight in this study (Table 5). Nir et al.
(1994) reported a greater gizzard development at 7 d of
age when chicks were fed diets that contained medium
and coarse particles. There had been a greater positive
effect on gizzard development when diets were fed in
a mash versus a pelleted or crumbled form likely due
to changes in particle size distribution after pelleting
(Amerah et al., 2007). Pelleting and crumbling of the
diets used in this trial likely diminished the positive
effect of particle size on gizzard development. The relative
weight of the pancreas increased linearly as TIU in
the ESBM were increased (P < 0.01; Figure 5). Veltman
et al. (1986) did not find significant differences
in performance and pancreas weight when chicks were
fed low trypsin inhibitor levels of 2.9, 4.4, 5.2, and 6.5
TIU/mg, which suggested that a certain level of trypsin
inhibitors must be fed to cause pancreatic hypertrophy.
The best performance was obtained when chicks were
fed coarse ESBM with intermediate TIU between 12.6
and 16.2 TIU/mg. Coarse ESBM increased feed intake
and BW in diets that contained more than 9.6 TIU/
mg. It was obvious that increasing the particle size of
the ESBM has consistently ameliorated the negative effects
(Pacheco et al., 2013, and current study) of trypsin
inhibitors. Therefore, particle size manipulation of
ESBM may be used as an alternative to improve live
performance when diets contain high levels of trypsin
inhibitors.