occludin, zonulin, interferon-gamma (IFN-γ), Transforming Growth Factor beta (TGF-β) and calprotectin. • Occludin and zonulin are tight junction proteins that, simplistically, can be considered part of the glue that keeps the cells of the intestinal epithelia connected. Reduced ex- pression of occludin and zonulin in faecal samples therefore indicates reduced intestinal integrity, inflammation and increased permeability. • IFN-γ is an important proinflammatory cytokine that also plays a regulatory role in the immune response and inflammation. • TGF-β is a multifunctional cytokine that plays an important role in regulating the inflammatory process that is often considered anti-inflammatory, although it can also have proinflammatory properties. • Calprotectin is a marker for intestinal inflammation be- cause elevated values in faeces indicate that white blood cells (neutrophils) have leaked into the luminal content. Zonulin and occludin are indicators for the status of tight junctions and thus intestinal integrity. Calprotectin, IFN-γ and TGF-β are indicators of immune activation and the inflamma- tory process, and the levels of calprotectin and IFN-γ are ex- pected to decrease when intestinal inflammation is reduced, while the levels of TGF-β, zonulin and occludin can be more difficult to interpret.


Biomarkers used to assess gut integrity Hemicell HT (Elanco) is a β-mannanase enzyme that degrades highly antinutritive β-mannan fibres found in most vegetable feed ingredients. The content in most of them is low, well below 1%, so typical swine diets are unlikely to contain more than 0.2–0.4% soluble β-mannan. However, their presence in common diets has been associated with a broad range of adverse effects. Mostly, these can be linked to the ability of β-mannan to provoke a wasteful immune response that causes intestinal inflammation and leakage that may increase susceptibility to disease challenges. The tool was used to evaluate intestinal health in the second batch of a recent nursery trial with piglets weaned at 21 days of age, conducted in France by MG2Mix. Standard control di- ets were compared to diets with 300g/tonne of the β-man- nanase enzyme, where 2% soy protein concentrate was re- placed with 2.7% soybean meal in phase 1, 6–10kg, and where the enzyme was formulated into the feed to replace 63kcal/kg NE in phase 2, 10–25kg. In total, 15 faecal samples were collected from each treatment at the end of the second batch, 41 days post-weaning. The piglets receiving the β-mannanase enzyme had better weight gain and feed efficiency and higher feed intake than the control pigs. Equally importantly, no differences were ob- served in health, faecal scores or mortality and no antibiotic treatment was needed during the trial. Knowing that im- proved intestinal integrity is typically accompanied by higher


Trials in piglets weaned at 21 days of age showed that adding a β-mannanase enzyme led to better weight gain and feed efficiency.


performance it was interesting to observe the results of the analysis for the five markers.


Level of immune activity That the expression of calprotectin and IFN-γ were signifi- cantly lower (p<0.05) on Hemicell HT compared to the con- trol group indicates that the levels of immune activity and in- testinal inflammation were reduced with the enzyme, which was expected because it reduces the ability of β-mannan to provoke an immune response. That the expressions of TGF-β and the two tight junction pro- teins, occludin and zonulin, were similar on both treatments may be more difficult to interpret. However, the good health status of the pigs likely played a role, so the results from the tool seem to support the performance differences. There is still much to learn about how to interpret the results, and the tool itself can likely also be improved, but the prelim- inary results are very promising because they indicate the tool may be useful to evaluate intestinal health in piglets.


References available on request.


Table 1 – Overall results, nursery trial – batch 2 only.


Initial weight, kg Final weight, kg Daily gain, kg


Feed intake, kg/day Feed conversion


Average faecal score * Hemicell HT, Elanco.


Control 6.390


23.657 0.345 0.544 1.589 1.172


β-mannanase* 6.300


26.497 0.404 0.606 1.509 1.172


P-value 0.0904 0.0001 0.0003 0.0010 0.0188 0.9980


▶ PIG PROGRESS | Volume 37, No. 2, 2021


19


PHOTO: BERT JANSEN


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