Fiber may be commonly included in diets in some sectors of the poultry industry, but its possible benefits to the broader industry remain underexploited. This, however, is changing and poultry producers might, in the not-too-distant future, be gaining the same, if not more, benefits from fiber as the swine industry now enjoys.
Speaking to Poultry International Drs. Carrie Walk, head of R&D, and Tara York, technical services director North America with additive and nutrition company AB Vista, explained that what has held fiber back in poultry diets is not so much lack of research, but rather a failure to directly associate functional and beneficial characteristics to dietary fiber type and specific fiber ingredients, as well as a lack of standardization in research findings.
Work being carried out by AB Vista, however, is looking to change this and develop a much clearer understanding of how different key outcomes can be achieved through informed fiber use.
The company is, amongst other areas, looking at how to optimize dietary fiber fractions to modulate microbial fermentation and promote beneficial bacterial growth, encourage production of beneficial microbial metabolites, such as short chain fatty acids, and improve production and feed efficiency in poultry. At the same time, AB Vista believes there is a need to standardize the definition of fiber fractions in ingredients and subsequently in diets. The company is investing significantly in advancing the understanding of fiber fractions, as well their different implications, with the aim of better defining the beneficial roles of different types of fiber in poultry nutrition.
As these processes are achieved, nutritionists will be able to use better understood factions in their rations to meet production needs, overcoming the current lack of clarity on which components within fiber are resulting in specific benefits, or problems, for birds.
Walk explained: “Previous research has looked at the objective of adding fiber to the diet, rather than what type of fiber or its concentration. You can find a lot of information on diet, density, satiety, gut fill and even microbiome modulation due to different kinds of ingredients, but the links to specific fiber components or fractions is missing.”
She continued: “Our recent development of a stimbiotic, which is a product designed to stimulate microbial fermentation in the gut and facilitate fiber utilization through the production of microbial enzymes, along with our gut health service, have paved the way to understanding the beneficial effects of fiber on microbial populations, fermentation, immune and gut function, short chain fatty acid production, and performance and efficiency in broilers and pigs."
Work is ongoing to accurately and rapidly quantify the various fiber fractions and how to utilize those in practical diets. Once this has been established and used routinely, the industry will be able to use standardized terms to describe fiber and manage those fractions to support specific beneficial functions and minimize antinutritional properties.
Walk continued: “This work should help to uncover why varying results with fiber are sometimes seen, along with the precise components within fiber that result in specific benefits for birds. We are beginning to dive down into the different physiochemical properties of fiber, such as soluble and insoluble fractions, and determine where they may result in either beneficial or negative effects on performance depending on the age or stag of the production cycle."
Gut health
It is now established that fiber plays a key role in gut health, particularly through its effects on the microbiome, fermentation and the production of short-chain fatty acids that support gastrointestinal integrity.
From a poultry perspective, it is recognized that different fiber sources – soluble, insoluble or fermentable - can influence digestion, nutrient absorption and gut motility and all of these factors impact bird performance.
York commented: “The question is no longer whether fiber is valuable, but how we can grow our knowledge effectively, identify the gaps that remain and develop practical solutions."
Within the gut, different types of fiber work in different ways. Insoluble fiber, for example, helps to stimulate gut motility and gizzard development, improving nutrient digestion and increasing feed efficiency. Soluble and fermentable fibers provide different benefits, being broken down by the microbiota to produce short-chain fatty acids, which fuel intestinal cells, support gut barrier function and create a favorable microbial balance.
Walk continued: “Recent published research showed in laying hens higher fiber diets resulted in a richer and more diverse microbiome and that was correlated to improvement in feed efficiency.”
York explained: “Establishing a good microbiome early on is important as it helps to limit or reduce the growth of pathogens. Incorporating insoluble fiber into the diets of sows or broiler breeders is believed to be beneficial as it leads to increased passage rate and, therefore, provides less time for potentially pathogenic bacteria to proliferate and take hold."
As the understanding of fiber continues to grow, rather than minimizing fiber in diets due to anti-nutritional factors, AB Vista’s researchers are investigating how various fiber fractions can be balanced and how enzymes and stimbiotics can be incorporated to further unlock fiber’s functional benefits.
Lessons from the swine industry
Fiber use is more advanced in the swine industry, allowing the poultry sector to gain from its knowledge. The swine sector has already moved to more standardized definitions, such as going from crude fiber to total dietary fiber, and has begun incorporating these values into dietary formulations.
Walk explains: “It seems the swine industry describes the ingredient concentration and it makes the link between the fiber fraction, the objective of feeding it and the concentration that’s in those ingredients. I think that we could do a bit more in the poultry industry to standardize our definitions and objectives to manage utilization of dietary fiber going forward."
Walk agreed that, in addition to understanding the different fiber fractions and the value they bring to performance, they are now beginning to look at biological markers to help demonstrate the impact of fiber on gut health. Two immunological markers in particular are being investigated as part of the ongoing work: calprotectin and fibronectin. Both can be found in the intestinal tract, and they offer an indication of immune function and the structural integrity of the gastrointestinal tract.
Walk further explained that, in piglets, due to feeding higher levels of wheat bran, they were able to detect higher levels of calprotectin in the feces, and the negative impact of feeding higher levels of wheat bran was negated through the use of a stimbiotic, which was demonstrated by lower levels of calprotectin. Trial data showed that, while high dietary fiber can elicit an immune repose, it can be mitigated through use of additives designed to improve fiber utilization. Studies have also shown that a one-size-fits-all recommendation is not possible, and this rather highlights the need to measure and manage dietary fiber, depending on the production status and stage of the animal.
While immune markers are important, the company is taking a much broader approach to understand the impact of fiber. This includes, for example, looking for beneficial bacteria, pathogenic bacteria and metabolites produced as a result of those populations and comparisons with benchmark data.
Walk added: “This gives us a holistic view of what could be happening in the gastrointestinal tract as a result of fiber but also stemming from other husbandry, dietary or environmental factors."
While the calprotectin and fibronectin are being worked on, more work still needs to be done. On the swine side, there have already been encouraging trends, but the markers are yet to be fully refined.
