Can fermented rye work as a substitute for antibiotics in broilers?

Fermented rye may inhibit pathogens and deliver immunomodulatory properties, thus providing a potential alternative for antibiotics in broiler diets, says Trouw Nutrition.

At the sixth Conference on Poultry Intestinal Health (IHSIG), ​held earlier this month in Rome, Petra Roubos, PhD, Trouw Nutrition R&D manager, presented on new research undertaken by her team; the work done showed how the prebiotic activity of fungal fermented rye modulated the microbiota and enriched Bifidobacterium​ population in broilers’ guts. 

The study ​

The study, in question, involved 264 Ross broilers divided over two treatments, she said.

The birds were infected on days 8 and 9 with Salmonella enteritidis​; on day 21 and day 35 the team did caecal collection of material from 18 birds per treatment, and looked at Salmonella​ counts as well as evaluating the microbiota composition using molecular tools, she said.

When comparing the caecal microbiota content between the control group and birds receiving fungal fermented products, the researchers noted differences among various bacterial populations, explained Roubos.

Birds receiving fermented rye showed increased bacterial diversity, she said. Specifically, the population of Bifidobacterium ​in birds receiving fermented rye was on average 5.8% compared to a control group at 1%. “We really saw an increase of this population in the experimental groups, and at a low inclusion rate of fermented rye, which [allowed us] to classify fermented rye as having a prebiotic effect.”​

The team also saw that Salmonella​ counts were numerically lower for birds in the fermented rye group compared to birds in the control group. “When the broilers have lower diversity they mainly shed Salmonella,” ​she told us.

Additionally, the researchers observed that the control group differed significantly concerning the presence of the Clostridium piliforme and Clostridium colinum​, which were not detected in birds receiving the fermented rye additive, said Roubos.

Feasibility​

There were many questions that followed Roubos’ IHSIG talk; delegates, for instance, asked about the viability of feed formulations including such an ingredient.

“We did a lot of feasibility studies around the cost price, because it is not a normal production process - we have to do solid state fermentation to produce the product.”  ​

The process involves the rye being sterilized and inoculated by the mycelium of certain mushrooms, and subsequently being stored in bags for a couple of weeks to let the mycelium grow. During fermentation, enzymes are generated and the rye is degraded, together with the growth of fungal biomass, resulting in the formation of new compounds.

“We are not so far into the research that we know exactly the active compounds; however, we already noticed sugars are degraded during the fermentation and also that smaller oligosaccharides are formed out of the rye.”​ ​ ​

Objective of research 

The decision to evaluate fermented rye arose after the research team had evaluated the literature and had done screening work to determine which products might deliver as antibiotic alternatives, could improve gut health, she said.

“Assay work compared a range of ingredients in relation to adhesion capacity to different pathogens. We found a very high binding capacity of the fermented rye to Salmonella and E.coli bacteria in particular. Further immune modulation was evaluated using a chicken macrophage cell line, observing an increased macrophage activity. We followed up on those findings with in vivo work.”​ ​

Some members of the IHSIG audience in Rome also wanted to know about the impact of fermented rye on performance parameters.

“My talk did not focus on performance results. The study I was presenting was one concentrating only on the microbiota and microbial reactions from using the fermented rye product.”​

However, in another study on fermented rye the team did see performance benefits as well. “It depends on the conditions of the experiment, the number of birds in the cohort, and whether there is a challenge or not.”​

“Neither have we done a study involving direct comparison of fermented rye with antibiotics. We have just been focusing on exploring the mode of action for the moment.”​

“If you see results indicating positive effects in the microbiota, however, you can assume fermented rye would be beneficial in terms of partial replacement of antibiotics, not necessarily on growth promotion but in relation to pathogen inhibition.”​

Immune system, prebiotic mode of action​

In terms of next steps, Roubos said the team wants to explore further the interactions within the intestinal tract, the impact of the fermented rye product on the immune system; they expect direct and indirect effects on that.

“We want to measure more parameters in respect of the immune system and we want to confirm the prebiotic efficacy in an additional study as well.”​