Over-processed meat and bone meal and phytase effects on broilers challenged with subclinical necrotic enteritis: Part 2. Inositol phosphate esters hydrolysis, intestinal permeability, hematology, jejunal gene expression and intestinal morphology

Abstract

This study investigated the hypothesis that feeding broilers over-processed meat and bone meal (MBM) would impair gut health in the absence of phytase and in turn, affect inositol phosphate (inositol xphosphate, IPx: IP3, IP4, IP5 and IP6) ester hydrolysis, intestinal permeability, hematology, jejunal gene expression and intestinal morphology during necrotic enteritis (NE). Ross 308 male broilers (<i>n</i> = 768) were assigned to one of 8 dietary treatments in a 2 × 2 × 2 factorial arrangement, with 6 replicate pens per diet and 16 birds per pen in a completely randomized design. Factors were: NE challenge (no or yes), phytase level (500 or 5,000 FTU/kg) and MBM processing (as-received or over-processed). For the NE challenge, half of the birds were challenged with field strains of <i>Eimeria</i> spp. on d 9 and 10⁸ CFU/mL of <i>Clostridium perfringens</i> strain EHE-NE18 on d 14 and 15. A 3-way challenge, phytase and MBM processing interaction was detected for IP5 (<i>P</i> < 0.05) and IP6 (<i>P</i> < 0.05) levels in the ileum. Birds fed low phytase had increased IP5 and IP6 in unchallenged birds only when diets contained over-processed MBM. Challenge with NE increased intestinal permeability as measured by serum fluorescein isothiocyanate dextran (FITC-d; <i>P</i> < 0.001), increased white blood cells (WBC; <i>P</i> < 0.001), decreased mean corpuscular volume (MCV; <i>P</i> < 0.001) and mean corpuscular hemoglobin (MCH; <i>P</i> < 0.05), and decreased crypt-tovilli ratio (P < 0.05). The over-processed MBM reduced the villi-to-crypt ratio (<i>P</i> < 0.05). A 3-way challenge × phytase × MBM processing interaction was detected for mucin 2 (<i>MUC-2</i>) expression (<i>P</i> < 0.05) where only in unchallenged birds fed over-processed MBM did high phytase reduce MUC-2 expression. A lower expression of aminopeptidase N (<i>APN</i>; <i>P</i> < 0.001) and vitamin D receptor (<i>VDR</i>; <i>P</i> < 0.001) were recorded in NE challenged birds. In conclusion, NE has a negative impact on the gut and hematology of broilers, but its effect on phytate hydrolysis is minimal.