Modulation of Gut Microbiota in Broilers: Silvafeed® Nutri P

The success of poultry industry is largely due to the genetic selection of broilers. Nowadays, the growth capacity of chickens has been greatly improved, implying the optimal and fast development of the digestive tract to improve feed utilisation. However, enteric disorders have raised major concerns in intensive poultry production and they have become reinforced by the progressive restriction of the use of antibiotics. Therefore, gut health, in the broadest sense, has become the main priority in livestock production.

The physiology of the gastrointestinal tract is extremely complex, involving interactions between dietary and host factors, as well as microbiota. Broilers’ intestinal microbiota is highly complex and plays an important role in the digestion and conversion of feed into body mass, while also affecting protection against pathogens, detoxification, and modulation of the immune system.

Research on the characterisation of gut microbiota in poultry has made great progress over the last decades. Most of the early works relied on limited culture-dependent approaches, considering the numerous microorganisms that are not culturable in the laboratory. The adoption of culture-independent methods has emerged in the mid-80s with denaturing gradient gel electrophoresis, restriction fragment length polymorphisms and clone libraries. More recently, the advent of high-throughput sequencing of 16S rRNA gene amplicons has enabled the study of bacterial communities at increased depth and resolution. This technology has been used to describe the functional diversity and natural variability of caecal microbiota, as well as the temporal and spatial variations that normally take place in the chicken gastrointestinal microbiota.

The modulation of intestinal microbiota has been speculated to be a key mechanism behind the growth promoting effects of antibiotics used at low doses in livestock animals. Likewise, changes in gut microbiota seem to be responsible for the beneficial effects of Silvafeed® Nutri P, a blend of plant extracts derived from the Italian Chestnut (Castanea sativa) and Argentinian Quebracho (Schinopsis lorenzii) which are the result of a fully sustainable and production process. The raw material (wood) is harvested from a well defined area around the manufacturing plants in compliance with local forestry regulations. The extraction process is eco-friendly, as simple as making a nice cup of tea. The wood is chipped and infused in hot water to extract the most beneficial molecules. Furthermore, the single extracts are blended together to maximise their synergistic action in animal nutrition. In fact, this blend has been shown to improve productive parameters and prevent infectious diseases in broilers, e.g. necrotic enteritis, under experimental and commercial conditions. In addition, available data suggested that their use does not contribute to the selection and spread of antimicrobial resistance and bacteria do not generate resistance against these plant extracts.

In order to understand how Silvafeed® Nutri P can improve the health and nutrition of chickens through the modulation of gut microbiota, high-throughput sequencing studies were performed under different experimental and commercial conditions. Results comparing animals treated using antibiotics or Silvafeed® Nutri P, showed that specific bacteria groups were similarly affected when this plant extracts blend was used. The bioactive substances present in Silvafeed® Nutri P have shown a strong inhibition activity against Clostridium perfringens and other poultry pathogens, both in vitro and in vivo. In contrast, some potentially beneficial bacteria such as Lactobacillus spp. are not affected at all.

Several studies reported that that caecal microbiota is dominated by Firmicutes and Bacteroidetes phyla, comprising 94% of the sequences. The ratio between phyla Firmicutes and Bacteroidetes in the gut microbiota has been linked to the efficiency in energy harvesting in different animals including mice, pigs, cows, and humans. A significant increase in the Firmicutes to Bacteroidetes ratio was observed for broilers supplemented with Silvafeed® Nutri P in different experimental and commercial trials. Furthermore, our extensive research on this topic showed that the inclusion of Silvafeed® Nutri P in the diet strongly reduced bacterial richness at different ages of poultry compared with untreated control. It has been hypothetised that a low microbial diversity, composed by the right bacterial species, would be essential to use the most relevant components of the digesta, including energy harvesting and nutrients.

Figure 1: effect of Silvafeed® Nutri P in gut microbiota modulation

The changes of caecal microbiota composition produced by Silvafeed® Nutri P were mainly associated with alterations in bacterial families Ruminococcaceae and Lachnospiraceae (Order Clostridiales). In fact, Silvafeed® Nutri P consistently and strongly increased the abundance of particular members of order Clostridiales and family Ruminococcaceae throughout the different rearing phases of the broilers. Moreover, high levels of other classified genera of the families Ruminococcaceae and Lachnospiraceae were observed especially in mature intestine. Likewise, previous reports showed a positive relation between the supplementation with effective growth-promoters and the caecal/faecal enrichment with different members of order Clostridiales, including Ruminococcaceae and Lachnospiraceae, which were linked to chicken performance improvement. Furthermore, Silvafeed® Nutri P increased the levels of Lactobacillus spp. and Bifidobacteria, two important bacteria that have a beneficial influence on gut health and nutrition, when compared with other growth promoters. The propensity of Silvafeed® Nutri P to favour potential probiotic bacteria could contribute to the improvement of broilers health and reduce pathogens burden during the productive cycle of poultry.

Silvafeed® Nutri P clearly modulates gastrointestinal microbiota in broilers. These changes represent an essential piece of evidence to explain the beneficial effects of Silvafeed® Nutri P on the productive parameters and intestinal health of poultry chickens in standard commercial farms.