It is widely accepted that factors like: animal age, diet composition, dietary fibre, feed particle size etc. will have a direct impact on animal performance. All these factors will also have an impact on microbial populations in the gastro intestinal tract (GIT).
The complexity of the gut as an organ and its microbiome and all possible interactions and synergies are far from being fully known, which makes the drawing of research conclusions also a complex subject.
Different research work has shown that high performing birds have a different microflora when compared with low performance birds. Moreover, research shows that NSP degrading enzymes alter the microbial populations at GIT and further that microflora shifts done by enzymes are substrate (feed composition) dependent.
Understanding how these shifts in microbial populations affect performance, hormonal response, gut development, etc opens the door for tailored nutritional solutions and gut microflora modulation to achieve optimal animal performance.
Mode of action beyond nutrient digestibility
Research done with broilers fed barley or oat based diets has shown that NSP degrading enzymes increase the amount of SCFA produced in the gut.
Nevertheless, it should be accepted that different enzymes (specifically different xylanases) will hydrolyse arabinoxylan (AX) at different extensions generating different degradation products and that the response on SCFA production is substrate and enzyme dependent leading to a significant variation in the research results.
Some NSP degrading enyzmes are able to hydrolyse AX (both soluble and insoluble fractions) and will form AX oligosaccharides (AXOS) and xylan oligosaccharides (XOS), molecules that are recognised for their prebiotic properties. Several studies with mammels showed that AXOS consumption was associated with health promoting effects, such as increased levels of SCFA and higher concentration of bifidobacteria.
Broiler trials
To evaluate the effect of an NSP degrading enzymatic complex, Hostazym® X, on animal performance and GIT microbial populations, two broiler trials were conducted and selected microflora populations and zootechnical performance were measured.
The two trials were set as 42 days grow out experiments using wheat, maize, soya based diets and two treatments (with 10 replicates of 10 birds) - a control group and an enzyme treated group (Hostaxym® X at 1500 EPU/kg feed). Crop, ileum and caeca contents pH, ileal and caecal selected microbial populations, and standard performance indicators were measured.
Table 1 summarises the results of both trials showing the measured parameters with significant differences (at p < 0.05 or 0.05≤p≤0.1). In both trials, the enzyme treatment, when compared to the control treatment, decreased pH in the caeca and increased total bacteria counts. Lactic acid producing populations were significantly better zootechnical performance (higher end body weight and lower FCR).
The pH decrease can be explained by fermentation processes, the AXOS and XOS generated by hydrolysis of fibre components are used by the intestinal microflora to produce SCFA (pH decrease), which can be used as an energy source by the bird enhancing its performance and health.
Conclusion
Despite the broiler's microbiome being a complex system influenced by several factors and interactions, possible synergistic effects and biochemical responses are far from being fully understood.
Research supports that beyond improved zootechnical performance, NSP degrading enzymes have a positive effect on gut health, by supporting the growth and maintenance of a balanced and positive microflora.
This article originally appeared in International Poultry Production Volume 27 Number 3.
