Effects of calcium level and source, formic acid, and phytase on phytate degradation and the microbiota in the digestive tract of broiler chickens

Abstract

Background Diet acidification, dietary calcium (Ca) level, and phytase supplementation are known influences on the microbial community in the digestive tract and on phosphorus (P) utilization of broiler chickens. Effects of dietary factors and microbiota on P utilization may be linked because microorganisms produce enzymes that release P from phytate (InsP6), the main source of P in plant feedstuffs. This study aimed to detect linkages between microbiota and InsP6 degradation by acidifying diets (i.e., replacing Ca carbonate (CaCO3) by Ca formate or adding formic acid to CaCO3-containing diets), varying Ca levels, and supplementing phytase in a three-factorial design. We investigated i) the microbial community and pH in the digestive tract, ii) prececal (pc) P and Ca digestibility, and iii) InsP6 degradation. Results All factors under investigation influenced digesta pH and the microbiota composition. Predicted functionality and relative abundance of microorganisms indicated that diets influenced the potential contribution of the microbiota on InsP degradation. Values of InsP6 degradation and relative abundance of the strains Lactobacillus johnsonii and Lactobacillus reuteri were correlated. Phytase supplementation increased pc InsP6 disappearance, with differences between Ca levels, and influenced concentrations of lower inositol phosphate isomers in the digestive tract. Formic acid supplementation increased pc InsP6 degradation to myo-inositol. Replacing CaCO3 by Ca-formate and the high level of these Ca sources reduced pc InsP6 disappearance, except when the combination of CaCO3 + formic acid was used. Supplementing phytase to CaCO3 + formic acid led to the highest InsP6 disappearance (52%) in the crop and increased myo-inositol concentration in the ileum digesta. Supplementing phytase leveled the effect of high Ca content on pc InsP6 disappearance. Conclusions The results point towards a contribution of changing microbial community on InsP6 degradation in the crop and up to the terminal ileum. This is indicated by relationships between InsP6 degradation and relative abundance of phosphatase-producing strains. Functional predictions supported influences of microbiota on InsP6 degradation. The extent of such effects remains to be clarified. InsP6 degradation may also be influenced by variation of pH caused by dietary concentration and solubility of the Ca in the feed.

Phytase Supplementation Effects on Amino Acid Digestibility in Broiler Chickens are Influenced by Dietary Calcium Concentrations but not by Acid-Binding Capacity

“…The correlations between the pcAAD and the relative abundances of OTU1 ( Lactobacillus johnsonii ) [except for alanine (Ala), His, and Met] and OTU10 ( Streptococcus alactolyticus ) (except for Cys) in the ileum content were significant ( Supplementary Table 3 ). The relative abundance in the ileum of these OTUs thereby ranged from 23.6–45.6% for OTU1 and 0.2–15.6% for OTU10 between treatments ( 18 ). Further correlations between relative abundances of OTU2 ( L. gallinarum ) and OTU13 ( L. reuteri ) in the crop content were significant for some AA.…”

“…Further correlations between relative abundances of OTU2 ( L. gallinarum ) and OTU13 ( L. reuteri ) in the crop content were significant for some AA. The relative abundances of these OTUs in the crop ranged from 11.1 to 28.7% and from 0.6 to 2.4% between treatments, respectively ( 18 ).…”

“…The present study was part of a large experiment and companion data on growth, pH, phytate degradation, pc Ca and P digestibility, gut microbial characterization, and predicted microbial functionality were recently published ( 18 ). All details of the animal trial are reported there and presented briefly herein.…”

“…Analyzed concentrations of P, Ca, phytate, phytase, crude protein, and AA are provided in Supplementary Table 2 . Details of ingredient composition and analyzed concentrations of proximate nutrients, gross energy, inositol phosphate isomers, and particle size distribution of the diets as well as particle size distribution of CaCO 3 and CaF are provided in the companion article ( 18 ). Experimental diets were provided from day 16 until the end of the experiment.…”

“…Hence, aspartic acid together with asparagine (Asx) and Glu together with glutamine (Glx) were analyzed. Descriptions of sample preparation, analyses of fractions other than AA, and microbiota analyses and functional predictions are provided in the companion article ( 18 ). In brief, a DNA extraction kit (FastDNA™ Spin Kit, MP Biomedicals LLC) was used to extract DNA from crop and ileum digesta samples and DNA was quantified spectrophotometrically with a NanoDrop 2000 device (Thermo Fisher Scientific).…”