Modes of Action
Prevention of attachment of harmful bacteria
Attachment of bacteria to mucus and the epithelial surface in the gut is necessary for them to colonize and multiply. Without attachment, bacteria such as the pathogenic strains of E. coli can't cause harm to the animal. Their attachment is highly specific, targeted at certain carbohydrate structures in the gut wall. By including similar sugar structures in the feed, it is possible to decrease their attachment.
Progut® contains both yeast cell wall (mannoproteins and betaglucans) and yeast extract (nucleotides, peptides etc.). Mannoproteins are mainly needed in preventing the attachment of pathogenic E.coli, Campylo- and salmonella bacteria to the gut, but at trials carried out at Danisco's Innovation Research Centre in Finland and at Giessen University in Germany, it was shown that E.coli strains agglutinate to both cell wall and yeast extract. The share of agglutination to these varies between strains. Therefore the combination of extract and cell wall is much more effective in preventing E.coli than a product only containing cell wall.
Hydrolysis increases the amount of bioactive soluble particles in the product. Amount of soluble particles correlate to E. coli binding ability.
Figure 1a and 1b. Correlation of the amount of soluble poly- and oligosaccharide sized material with the bacterial adhesion analysis results of five Progut® batches. Panel A. Relative amounts of soluble poly- and oligosaccharide -sized material as measured by gel-permeation chromatography (GPC). Panel B. E.coli bacterial adhesion analysis results.
Modulation of gut microflora
Each animal species seem to have a normal intestinal microbiota, which consists of certain bacterial species in proportions typical to the host animal and it develops gradually during the growth. Healthy animals receiving the same feed have rather similar microflora.
To be able to form a quick and understandable overview of the complex microbiota, a new concept of Microbial Balance Index (MBI) was developed. The ratio is calculated from the proportions of Bifidobacteria, enteric group bacteria, butyric acid production related bacteria, and Bacteroides-Porphyromonas-Prevotella -group bacteria.
In feeding trials with piglets, pigs, turkeys and broilers MBI was found to correlate significantly with the growth and feed conversion (FCR) of the animals. As an example, results from piglet and pig feeding studies are presented in figure 2 and 3. In these trials MBI had a significant correlation coefficient with growth (r = 0.68, P ≤ 0.01). The correlation of MBI and growth emphasizes the importance of the microbiota in animal health and productivity. The findings indicate that MBI could be used as a biomarker of well-functioning gut, which is a prerequisite for good growth.
Pig Trials
Figure 2. The correlation between MBI and DWG. Symbols:
□ measured values from each animal group participating in trials;
■ regression analysis predicted values.
Figure 3. The correlation between MBI and FCR.
Progut® has been found to increase MBI with piglets and poultry and to have beneficial effects on animal performance. In a trial conducted at Munkkila Research Farm in 2005 the piglets (14-24 kg) fed with Progut® tended to have higher MBI and average daily gain than the controls (Figure 4). Similar results have been obtained with poultry.
Figure 4. The effect of Progut® on MBI (P = 0.20) and growth (P = 0.07) of piglets. Munkkila Research Farm, Finland 2005.
A feeding trial carried out at Munkkila Research Farm in Finland in 2005 showed that Progut® added to piglet feed can help to stabilise intestinal microbiota during weaning and to help keep proportions of different faecal bacterial species more stable (figure 5). Piglets receiving Progut® also seemed to grow better than the control group (DWG = 63g higher).
Figure 5. The effect of feeding on microbial counts at weaning and at three weeks post-weaning
IgA secreation to the gut and immune cells on gut layer
Yeast betaglucans are also considered beneficial in stimulating immunity. Nucleotides are known for their effect in stimulating immunity and the growth of lactic acid bacteria and Bifidobacteria in the gut. They are also considered to be beneficial in gut development and healing infections.
IgA is a watchdog in the gut that neutralises toxins secreted by pathogens and prevents attachment of bacteria to mucosa. It also decreases the energy losses of immunity by lowering the need to activate other parts of the immune defence system. Improved IgA production decreases disease stress and correlates positively with body weight of animals in challenged environments (Rautonen and Apajalahti, 2002). Active secretion of IgA can serve as a biomarker for well-balanced gut immune functions. Progut® has shown in a number of trails (e.g. Danisco's Innovation Research Centre) with different species to increase the IgA content in the gut and its effects have been constant (figure 6).
Research has also shown that Progut® increases IgA content of colostrum of sows. This might be beneficial for piglets due to the better natural protection in the intestine against pathogenic bacteria. t the same research centre, Progut® has shown to increase the number of immune cells in the gut epithelium (figure 7). Compared to a commercial yeast betaglucan product with the same inclusion rate in feed, Progut® increased the amount of immune cells by 30%.
Figure 6. The effect of Progut® on the IgA concentration in the gut digesta
Figure 7. The effect of Progut® on the amount of immune cells in the gut epithelium