Influence of meat and bone meal, phytase, and antibiotics on broiler chickens challenged with subclinical necrotic enteritis: 2. intestinal permeability, organ weights, hematology, intestinal morphology, and jejunal gene expression

Abstract

Undigested proteins entering the hindgut may favor the proliferation of Clostridium perfringens. Using phytase to eliminate the need for meat and bone meal ( MBM) as a P source may reduce potential infection with C. perfringens. A study was conducted to determine the impact of MBM, phytase, and antibiotics ( AB) on intestinal permeability and morphology, organ weights, and jejunal gene expression in Ross 308 chickens challenged with subclinical necrotic enteritis ( NE). Male Ross 308-day-old chicks (672 each) were randomly allocated to 8 treatments with 6 replicate pens each housing 14 birds. A 2 × 2 × 2 factorial arrangement of treatments was used: MBM (no or yes); AB (no or yes—Zn bacitracin 100 in S and 50 ppm in G/F and salinomycin Na 60 ppm in all phases); phytase (500 or 1,500 FTU/kg, both using 500 FTU matrix values) using wheat-SBM-canola meal diets. Birds were challenged with Eimeria spp on day 9, and C. perfringens strain EHE-NE18 on day 14 and 15. An AB × MBM interaction ( P < 0.05) was detected for relative gizzard weight (with contents) being lower in birds fed MBM and AB compared to those fed MBM and no AB. A MBM × AB interaction ( P > 0.01) was detected for lymphocyte counts being lower with MBM and AB compared to MBM without AB. A phytase × AB interaction ( P < 0.05) was observed for villi length being increased with high phytase and no AB compared to with AB. Inclusion of MBM increased ( P < 0.05) blood FICT-d concentration, whereas AB decreased it ( P < 0.05). Antibiotics increased RBC ( P < 0.05), Hgb ( P < 0.05), and PCV ( P < 0.05) and expression of Ca-binding protein, CALB1 ( P > 0.05). Inclusion of MBM decreased expression of MUC2 ( P < 0.05). Results indicate that dietary MBM has a detrimental effect on gut health of broilers but this may be counteracted using AB.