Increasing the structural components in the diet, namely through including coarse grain particles in diets and manipulating the dietary fibre composition, has been shown to improve gut health, feed utilisation and production efficiency. This is primarily because structural components physically stimulate activity in the fore gut. An example of this is dietary non-starch polysaccharides (NSP), namely insoluble NSP, which have been shown to instigate beneficial effects on gut health, litter quality and nutrient utilisation, by increasing crop and gizzard activity, stimulating digestive enzyme production and enhancing bacterial fermentation in the hind gut. However, there is a lack of consistency with regard to the direct effects of dietary fibre on chicken health and production. The aim of this review therefore is to explore the impact of feeding different sources of fibre and different size grain particles on gut health and microflora, nutrient utilisation, performance and litter quality in broilers.

Subclinical necrotic enteritis (NE) is primarily caused by the gram-positive bacterium, Clostridium perfringens (Cp). The trend towards removal of in

Measures to improve bird performance have been sought due to the imminent phase out of in-feed antibiotics in poultry and continued demand for higher poultry feeding efficiency. Increasing grain particle size and dietary fibre may improve gizzard function, digestive efficiency and nutrient absorption. This study was conducted to evaluate the effect increased particle size of corn and inclusion of sugarcane bagasse (SB) on mRNA expression of genes encoding digestive enzymes and nutrient transporters in broilers. A total of 336 day-old Ross 308 males were assigned in a 2 × 2 factorial arrangement of treatments with corn particle size - coarse 3576 μm or fine 1113 μm geometric mean diameter, and SB - 0 or 2% inclusion. Feed conversion ratio (FCR), weight gain and feed intake were measured from d 0–10 and d 10–24. The relative gizzard weight and mRNA expression of genes encoding digestive enzymes and intestinal nutrient transporters were measured on d 24. During d 10–24, a particle size × SB interaction was observed for FCR (P < 0.01), where birds fed coarsely ground corn (CC) with 2% SB had lower FCR than those fed CC without SB. A particle size × SB interaction was observed for both expression of pepsinogen A and C (P < 0.01) which were negatively correlated with FCR on d 24. Addition of 2% SB upregulated pepsinogen A and C only in CC fed birds. Further, 2% SB also upregulated pancreatic amylase (AMY2A) and intestinal cationic amino acid transporter-1 (CAT1). Inclusion of dietary CC upregulated duodenal amino peptidase N (APN), jejunal alanine, serine, cysteine and threonine transporter-1 (ASCT1), and ileal peptide transporter-2 (PepT2). These results suggest that both SB and coarse particle size modulate expression of genes encoding important digestive enzymes and nutrient transporters and thus are directly related to bird performance. These findings provide insights into the combination effects of dietary fiber and particle size in the future management of broiler feeding.

A total of 90 male Ross 308 broiler chicks were used in a digestibility and performance bioassay to explore the effect of reduction in dietary protei

Structure of fibre has been reported to enhance performance, intestinal function and modify the composition and quantity of the microbial population in the chicken gastrointestinal tract. It is hypothesised that insoluble fibre in oat hulls may improve gut health and reduce intestinal Clostridium perfringens number. This research assessed the effect of free choice oat hulls (OH) on performance and gut microbiota in broilers during a mild (subclinical) necrotic enteritis (NE) challenge. A total of 240 day-old male Ross 308 broiler chickens were assigned to 24 cages in a 2 × 2 factorial arrangement of treatments. Factors were challenge - or +; and OH - or +. On d 16, challenged broilers had lower weight gain and feed intake (P < 0.05) compared with unchallenged broilers. On d 16, broilers given OH had lower feed intake (P < 0.05) and tended to have lower (P = 0.062) feed conversion ratio (FCR) compared with those without access to OH. Broiler performance, however, was not affected by OH nor by challenge on d 24 and 35. The broilers given OH had heavier gizzards (P < 0.05) compared with those without OH at d 35 but not at d 13 or 16. Increased numbers of C. perfringens (P < 0.001) and reduced numbers (P < 0.05) of Lactobacillus and Salmonellae were observed in the caecal contents of challenged broilers on d 16. Challenged broilers had a lower concentration of caecal acetic acid (P < 0.01) compared with unchallenged broilers at d 16. The broilers given OH had lower concentrations of caecal acetic acid (P < 0.05), propionic acid (P < 0.05), and valeric acid (P < 0.01) compared with those without access to OH. An OH by challenge interaction on succinic acid concentration was observed on d 16 (P < 0.05). Oat hulls elevated the caecal succinic acid concentration only in the unchallenged broilers. This study indicated a positive role of OH through improved gizzard function and increased succinic acid in the gut but its role in controlling NE was not conclusive.

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.