ABSTRACT The objectives of this study were to determine
the availability of P from mineral phosphate
sources by using different basal diets and measurement
of P retention and prececal (pc) P digestibility as well
as pc myo-inositol phosphate (InsP) degradation in
broilers. Semi-synthetic and corn-soybean meal-based
basal diets were used in experiment 1, and corn-based
and wheat-based basal diets were used in experiment 2.
Anhydrous monosodium phosphate (MSPa) or monocalcium
phosphate monohydrate (MCPh) was supplemented
to increment the P concentration by 0.05, 0.10,
and 0.15% or by 0.075 and 0.150% in experiments 1
and 2, respectively. Titanium dioxide was used as an indigestible
marker. Diets were pelleted through a 3-mm
screen. In experiment 1, retention was measured based
on total excreta collection from 20 to 24 d of age using
7 replicated birds per diet. In experiment 2, digesta
from the terminal ileum was collected from 22-d-old
broilers penned in groups of 19 with 5 replicated pens
per diet. The P retention response to supplemented
MSPa did not differ between the 2 basal diets in experiment
1. The response in pc P digestibility to MCPh
supplements also did not differ between the 2 basal
diets in experiment 2, as calculated by linear regression
analysis. Hydrolysis of InsP6 measured on both the excreta
and pc levels was high in the basal diets without a
mineral P supplement. Mineral P supplementation significantly
decreased (P < 0.05) InsP6 hydrolysis from
the InsP-containing diets in both experiments. Thus,
the choice of the basal diet did not affect the evaluation
of the supplemented mineral P source. However, calculated
values for mineral P sources need to be adjusted
for the decline in hydrolysis of InsP contained in the
basal diet that results from the P supplement
ABSTRACT The objectives of this study were to determinethe availability of P from mineral phosphatesources by using different basal diets and measurementof P retention and prececal (pc) P digestibility as wellas pc myo-inositol phosphate (InsP) degradation inbroilers. Semi-synthetic and corn-soybean meal-basedbasal diets were used in experiment 1, and corn-basedand wheat-based basal diets were used in experiment 2.Anhydrous monosodium phosphate (MSPa) or monocalciumphosphate monohydrate (MCPh) was supplementedto increment the P concentration by 0.05, 0.10,and 0.15% or by 0.075 and 0.150% in experiments 1and 2, respectively. Titanium dioxide was used as an indigestiblemarker. Diets were pelleted through a 3-mmscreen. In experiment 1, retention was measured basedon total excreta collection from 20 to 24 d of age using7 replicated birds per diet. In experiment 2, digestafrom the terminal ileum was collected from 22-d-oldbroilers penned in groups of 19 with 5 replicated pensper diet. The P retention response to supplementedMSPa did not differ between the 2 basal diets in experiment1. The response in pc P digestibility to MCPhsupplements also did not differ between the 2 basaldiets in experiment 2, as calculated by linear regressionanalysis. Hydrolysis of InsP6 measured on both the excretaand pc levels was high in the basal diets without amineral P supplement. Mineral P supplementation significantlydecreased (P < 0.05) InsP6 hydrolysis fromthe InsP-containing diets in both experiments. Thus,the choice of the basal diet did not affect the evaluationof the supplemented mineral P source. However, calculatedvalues for mineral P sources need to be adjustedfor the decline in hydrolysis of InsP contained in thebasal diet that results from the P supplement
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