Abstract:
A total of 1,440 straight-run Heritage
56M × fast-feathering Cobb 500F broiler birds were
fed from 11 to 13 d of age to determine the impacts
of calcium (Ca), phytate phosphorus (PP), nonphytate
P (nPP) and phytase concentrations on the
myo-inositol hexakisphosphate (IP6) flow through the
different parts of gastrointestinal tract (GIT). The experiment
was a 2×2×2×3 randomized block design with
2 Ca (0.7 and 1.0%), 2 PP (0.23 and 0.34%), 2 nPP
(0.28 and 0.45%) and 3 phytase (0-, 500-, and 1,000-
phytase unit (FTU)/kg) concentrations. The experiment
was replicated twice (block) with 3 replicates per
treatment (Trt) of 10 birds per block. Concentration
of IP6 in crop, proventriculus (Prov) plus (+) gizzard
(Giz) and distal ileum digesta as well as the ileal
IP6 disappearance was determined at 13 d of age. In crop, higher IP6 concentration was seen with increased
Ca (P<0.05). Despite the interaction between PP and
phytase, higher dietary PP led to greater IP6 concentration
(P<0.05). Similar main effects of PP and phytase
were also seen in Prov+Giz and ileum (P<0.05)
without interactions. Interaction between Ca and nPP
on IP6 concentration was seen in Prov+Giz (P<0.05).
Decreased ileal IP6 disappearance was found at higher
Ca (62.3% at 0.7% Ca vs. 57.5% at 1.0% Ca; P<0.05).
In general, adding phytase improved IP6 degradation
but the degree of impact was dependent on nPP and
PP (P<0.05). In conclusion, phytase inclusion significantly
reduced IP6 concentration and IP6 disappearance
in distal ileum regardless of GIT segments or diet
composition, but impacts of dietary Ca, nPP, and PP
differed depending on GIT segment examined.
