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Figures
MDP, activating NOD2, which has an anti-inflammatory ac- tion and influences host response to improve intestinal health.
PGN challenge A recent study was designed to offer in vivo proof that an exogenous muramidase (Balancius) breaks down PGNs in the gut lumen of broilers. Also to investigate how it may re- duce inflammatory effects on the intestinal mucosa, thereby improving feed efficiency and gut health. To do this a novel PGNs challenge model was designed at Wageningen Live- stock Research. In order to invoke a consistent and signifi- cant challenge to the broiler gut, a known amount (2.6g/kg) of PGNs, isolated from Bacillus subtilis, was used. This is ap- proximately double the amount of PGNs that broilers would be exposed to under standard conditions. From 0-21 days broilers were fed one of four experimental rations based on maize and soyabean meal. PGNs were added to two of the treatments, one of which was also supplemented with the 35,000 LSU (F)/kg of exogenous muramidase. A further treatment had only the exogenous muramidase added to the control diet. While performance was evaluated, the set-up of the trial was not designed to demonstrate performance differences but rather to look in- depth at the effects of PGNs in the gut of broilers. To do this, blood, digesta and intestinal tissue samples were evaluated at two and three weeks of age. The inclusion of an exogenous muramidase, with and with- out PGNs, significantly increased the solubility of peptido- glycans in small intestinal digesta (Figure 1). This demon- strated the in vivo activity of the exogenous muramidase that, as expected, broke down PGNs in the gut lumen.
Intestinal health The gut microbiota provides key protection against patho- gens and is sensitive to disturbance which can lead to in- flammatory responses in the gut. If this happens gut func- tionality is affected; including barrier function, nutrient digestibility and absorption capacity. It has been reported that the absorption of carotenoids decreases during enteric infections. On day 20 of the study, the concentration of total carotenoids in plasma was significantly higher in birds re- ceiving an exogenous muramidase. These results suggest that this inclusion stimulated the intestinal absorption of di- etary carotenoids and improved intestinal barrier function by counteracting the negative effects of PGNs in the intesti- nal lumen and on gut barrier function. As carotenoids are absorbed with fats, they are a potential marker for the di- gestibility of fat in poultry and may also have a relationship with gut barrier function. For example, an Eimeria challenge (coccidiosis) reduces intestinal barrier function and also reduces plasma levels of carotenoids.
40 ▶ POULTRY WORLD | No. 5/6, 2021
Figure 1 - The addition of an exogenous muramidase (Balancius) increased the % of soluble PGNs, in jejunal digesta of broilers on day 14 and 21 (Jansman et al. – unpublished).
50 60 70
10 20 30 40
0 Control Balancius
A, BColumns with a different superscript have values that differ significantly at P<0.05.
This study demonstrated that the PGNs challenge increased the influx of intraepithelial lymphocytes and represented a challenge to the local immune system (Jansman and others, unpublished). Birds receiving a diet with both PGNs and an exogenous muramidase did not show such an increase in intraepithelial lymphocytes. This suggests a positive effect on the local immune system – moderating inflammatory re- sponses in the gut mucosa under challenge conditions. Subtle changes in genes related to small intestinal epithelial integrity and epithelial function were also observed when muramidase was included in the diet.
More to learn The risk of PGNs to intestinal health and optimum produc- tion is constant. This new study confirms the positive effects of supplementing diets for broilers with an exogenous muramidase. It also answers more questions about the negative effects of PGNs on performance. Its importance is due to the information provided on ways to maintain gut homeostasis and hence support the efficiency of poultry production. Exogenous muramidase activity increased the solubilization of PGNs in the digestive tract and reduced the inflammatory effects of PGNs that affect intestinal function- ality. However, there is still more to learn and further studies on the mode of action of exogenous muramidase will help explain its ability to unlock hidden potential in poultry. Understanding the processes involved can help scientists to improve animal health, welfare and performance. Doing this in a sustainable manner will also help the industry to meet the growing demand for animal products from a growing world population.
References available on request. Day 14 Day 21 B B
A A
Soluble peptidoglycan, % of total
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