In the previous editions, benefits of increasing post-ileal fibre fermentation through supplementation of β-1,4-endo-xylanase and the ability of xylanase + xylo-oligosaccharides to train microbiota to maximise fibre fermentation were discussed. AB Vista recently launched Signis in selected countries which is a complementary dual action microbiome stimulator that is designed to prepare the surface of dietary fibre be more digestible for fibre degrading bacteria and at the same time to train the microbiota to ferment fibre more efficiently. In this issue, a recent study comparing piglets' response to supplemental xylanase + xylo-oligosaccharides (Signis, AB Vista) with mannan-oligosaccharides and fructo-oligosaccharides will be discussed.

In a study by Cho et al. (2019ab, Advances in Animal Biosciences, In Press), a total of 144 piglets weaned at 28 days of age (initial body weight 7.5 ± 0.7kg) were allocated to 6 treatment groups (Figure 1). Three-phase feeding were applied (14 days each) and all diets were formulated to meet or exceed NRC nutrient requirements of piglets (NRC 2012). No antimicrobial growth promotors were included and total diet zinc levels were maintained to less than 150 ppm to meet the proposed EU standard effective from 2022. Piglets were housed either in a sanitary condition or a poorer sanitary condition. Sanitary condition is defined as rooms and pens were cleaned/disinfected before allocating piglets and poorer sanitary condition is defined as no cleaning and disinfection in a previously populated room. The design essentially mimics All-In All-Out system vs. continuous flow production system which are the two major systems used in commercial pork production. The study lasted for 6 weeks after weaning.

Figure 1. Experimental design to test the efficacy of Signis, mannan oligosaccharides (MOS) and fructo-oligosaccharides (FOS) under sanitary and poorer sanitary c onditions. Inclusion level of additives: Signis 100g/MT, MOS 1kg/MT and FOS 2kg/MT following manufacturers recommendation.

Before looking at the results we tested whether rearing piglets in a poorer sanitary condition imposes any physiological and immunological challenges. As expected, piglets housed in a poorer sanitary condition were 1.3kg lighter (22.4 vs 21.1 kg, P<0.001) at the end of the 42 day trial, had higher plasma endotoxin and TNF-α levels (P<0.001), and increased diarrhea index (10.8 vs 4.7%, P<0.001, expressed as the proportion of days with diarrhea over 14 days post-weaning). These results indicate that the poorer sanitary conditions used in this experiment provoked a degree of nutritional and immunological responses.

The left-hand side graph in Figure 2 shows the average daily gain response to the treatments. The results clearly showed that ADG was significantly decreased when pigs are housed in a poorer sanitary condition but supplementation with Signis removed the loss of performance due to the sanitary challenge. At least part of this ADG response is explained by the reduction in pro-inflammatory cytokine TNF-a concentration in the plasma with feeding Signis to piglets housed in a poorer sanitary condition. The most likely explanation for these findings is that Signis stimulated proliferation of fibre fermenting microbiota and hence reduced the exposure to pathogenic bacterial challenge under poorer sanitary conditions, which translates to decreased nutrient partitioning to the immune system and subsequent inflammatory response. Interestingly, Signis improved ADG in piglets housed in both sanitary and poor sanitary conditions. This observation indicates that Signis also increased energy and nutrient extraction, with the result that the improved ADG observed under poorer sanitary conditions would be a combination of increased energy and nutrient extraction and lower energy and nutrient partitioning to the immune system. Another noticeable finding is that neither MOS nor FOS, commonly included to address weaning challenges, improved performance of piglets under poorer sanitary condition, despite their inclusion levels being 10- to 20-fold higher than Signis.

Figure 2. Average daily gain and plasma TNF-α concentration in piglets housed either sanitary or poorer sanitary condition (denoted as P) and without/with supplementation of Signis, MOS or FOS (Cho et al., 2019 a, Advances in Animal Biosciences, In Press).

Fermentation characteristics of piglets measured in faecal samples are presented in Figure 3. Signis, MOS and FOS all increased production of volatile fatty acids and decreased production of branched chain fatty acids but Signis was more efficient in all cases. This finding, collectively with the performance and pro-inflammatory cytokine data, supports the notion that Signis stimulates fibre fermenting microbiota and hence increases energy extraction and reduces protein fermentation that is generally associated with pathogenic bacterial activity in the hind gut.

Figure 3. Total volatile fatty acids (VFA) and branched chain fatty acids (BCFA) concentration in piglets housed either sanitary or poorer sanitary condition (denoted as P) and without/with supplementation of Signis, MOS or FOS (Cho et al., 2019b, Advances in Animal Biosciences, In Press).

To conclude the series of recent research highlights, enhancing fibre fermentation has number of beneficial effects including (1) increases energy extraction via production of short chain fatty acids, (2) promotes healthier microbial composition that leads to reduced susceptibility to pathogenic bacteria and thus subsequent inflammatory responses, and (3) reduces nutrient partitioning to the immune system which then directed to the protein and energy retention. More than 10 internal trials indicate that Signis as a dual action fibre fermenting microbiome stimulator can offer a consistent response in both wheat- and corn-soy-based diet and results in better performance and healthier microbial composition.

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Article made possible through the contribution of Jae Cheol Kim, technical manager ASPAC, AB Vista

Roles of fibre fermentation in monogastric animals: 3. Dual action microbiome stimulator "Signis" maximises fibre fermentation