AB Vista Highlights the Latest Research and Key Takeaways From The Dietary Fiber Symposium at ASAS

Event sponsored by AB Vista

Author: Spenser Becker of AB Vista

More than 900 hundred students, researchers, and industry professionals gathered in Madison, Wisconsin March 11–13 for the annual ASAS Midwest meetings. The event featured many outstanding presentations and discussions related to nutrition, health, genetics, and management, all with the goal to keep driving the animal industry forward.

The Nonruminant Nutrition Symposium focused on dietary fiber and its benefits in swine production. With a greater focus on increasing sow longevity, reducing mortality, and improving production efficiency, there is a large interest in the North American industry to evaluate the beneficial effects of dietary fiber in gilt development, gestation, sow transition, and lactation. Likewise, this research area extends to nursery pig nutrition and understanding how dietary fiber can impact nursery pig health and productivity. Continuing reading below to find out the key takeaways of the invited speaker presentations.

Kicking Off with Dr. Amy Petry

The symposium kicked off with Dr. Amy Petry, assistant professor at the University of Missouri, who presented, “Beyond solubility: Navigating the complex landscape of dietary fiber in swine digestion and physiology.” Dr. Petry gave insights into the wide array of definitions that can be used for fiber and asked whether pigs really need fiber. The answer? Yes, pigs need fiber, but as with most concepts with fiber, it is complicated. For grow-finish pigs, typical corn-soy diets provide enough fiber; however, if pigs are deprived of fiber, beneficial gut microbiota die off.

Historically, fiber has been considered an antinutrient in swine diets as it dilutes dietary energy, increases the heat increment of feeding, and reduces feed intake and carcass yield. Despite this, we know that there are several benefits to feeding fiber to pigs. Highly fermentable fibers can improve intestinal fermentation and beneficial bacterial growth while also improving anti-inflammatory status, increasing intestinal barrier integrity, and serving as an energy source.

On the other hand, lowly fermentable fibers can increase intestinal passage rate, thereby reducing pathogen proliferation and adhesion and improving overall gut health. Much of our further understanding of fiber in swine nutrition has come from improvements in fiber analysis. Crude fiber does little to characterize fiber in ingredients and underestimates dietary fiber by 30 to 60%, leading Dr. Petry to conclude that we should abandon this assay altogether.

The detergent fiber system is a cost-effective way to understand the insoluble fiber fraction of ingredients; however, it does not provide the soluble fiber fraction and there is considerable lab-to-lab variation and method reporting. Additionally, the detergent fiber system can often overestimate insoluble fiber in co-products due to ingredient processing. Today, total dietary fiber is the most accurate fiber assay. While there are limitations with higher costs, lower throughput, and methodology variation, TDF allows for the capture of the majority of the fiber fractions and provides both insoluble and soluble fiber values. The final and most complete analytical option available is non-starch polysaccharide analysis. The analysis of NSPs provides insights to the individual monosaccharide components of fiber, which can be useful when evaluating fermentation potential and possible strategies to increase it. However, NSP analysis does not have an approved AOAC methodology, leading to high variability in addition to the very expensive cost and technically challenging assay. Despite these capabilities in fiber analysis, it is important to remember that they provide limited insight into the physiological impacts of fiber on the animal, such as fermentability, water holding and binding capacities, satiety, intestinal health, and digestion and absorption. Therefore, if we want to gain a better understanding of dietary fiber for practical diet formulation, we need to look beyond solubility and link the chemistry to the function and physiology within the animal.

Dr. Nick Gabler Focuses on Benefits & Challenges

Adding to the fiber discussion was Dr. Nick Gabler, John F. Patience Professor in Swine Nutrition at Iowa State University. Dr. Gabler focused on highlighting “The Benefits and Challenges of Dietary Fiber in Nursery Pig Diets.” In the nursery pig, dietary fiber application is more complex and less clear than in the older animal. Dr. Gabler highlighted the multiple functional properties of fiber that can be beneficial in nursery pigs, including fermentability, viscosity, pathogen binding, and water hold capacity. Given the many functions of fiber, we need to ask what exactly the goal is of feeding fiber to the nursery pig and what we should formulate for. We know that fiber dilutes dietary energy and can reduce nutrient digestion and absorption at high levels.

Dr. Gabler discussed the concepts of insoluble and soluble fibers in the nursery pig. Fiber plays an important role in establishing the microbiome and reducing hindgut protein fermentation, and insoluble fiber can be beneficial during disease challenges for binding pathogenic bacteria and preventing intestinal adhesion and proliferation. Depending on the source, soluble fiber types can contribute to large intestine fermentation and production of short-chain fatty acids, and they have also been shown to reduce E. coli. However, including a rapidly fermentable fiber source in theearly nursery may be contradictive due to the limited digestive capacity of piglets. What fiber should we use in the nursery? In an E. coli challenge study comparing a corn-soy control diet with diets containing either oats, soy hulls, or wheat bran, oats increased large intestine fermentation; however, no benefits were observed in scour scores or growth performance. In a second study aimed at answering the question of whether insoluble (wheat middlings) or soluble fiber (sugar beet  pulp) is beneficial in early nursery diets vs. late nursery diets in a US corn-soy-based diet, dietary formulation strategy had minimal impact on nursery pig scouring, removals, or growth performance. Unfortunately, several factors contribute to successful application of fiber in nursery pig programs. Across the literature, there exists a wide variety of weaning ages, pre-existing conditions, dietary fiber inclusions, formulation strategies, fiber particle size, feed processing methods, length of feeding, level of disease challenge, and outcomes measured that make the story of fiber in the nursery pig rather complex and without many conclusions, particularly in US corn-soy-based diets. Most of these studies are also limited to only the nursery period, without further evaluation on lifetime of productivity. In controlled settings, the role and properties of fiber are more well-defined; however, in corn-soybean meal diets and in pigs with mild to moderate health, the role of fiber needs further evaluation.

Unlocking the Value of Dietary Fiber with Dr. David Rosero

In the second half of the session, Dr. David Rosero, assistant professor at Iowa State University, presented on “Feeding the Modern Sow: Unlocking the Value of Dietary Fiber.” The modern sow has a high capacity for total born piglets and milk production compared to ten years ago. Unfortunately, this has also resulted in increases in sow mortality, particularly due to prolapse and structural issues in the United States. Compared to other countries where sow fiber intakes are higher, these challenges are far less. When applying fiber to sow diets, there are three phases to consider: Gestation, peripartum, and lactation. Gestation diets in the US based on corn, soy, and DDGS typically allow for ~230 g/d of TDF intake and ~30 g/d of soluble fiber intake, whereas gestating sows in European countries typically have >350 g/d of TDF intake and >50 g/d of soluble intake. In a small literature review, feeding gestation diets at or above these European dietary fiber levels was shown to increase litter weaning weight, number of pigs weaned, and lactation feed intake. Further commercial research in the US showed that increased TDF at 18% was beneficial for controlling sow body weight and body condition throughout gestation. However, changing the insoluble dietary fiber to soluble dietary fiber ratio did not have any impact.

Dr. Rosero also discussed a recent field trial in a farm that experienced high mortality and prolapses that compared a typical US diet based on wheat with a high fiber diet formulated with 23.4% soyhulls in the first phase and 20% wheat + 40% soy hulls in the second phase of gestation. Sows receiving the high fiber diet had reduced piglet mortality by 2% and reduced sow mortality by 2.7%. This reduction in sow mortality was largely due to reduced lameness (~1.9%) and prolapse (~0.9%). Evaluation of fiber during the 3 to 5 days prior to farrowing continues to be an area of interest, as it represents an important transition of the sow and a potential low-cost opportunity to include fiber and improve sow and piglet performance. We know from work from the late Dr. Peter Thiel’s lab that farrowing duration is reduced if sows have access to feed a minimum of three hours prior to farrowing. This leads to reductions in farrowing assistance as well as stillborn rate. Using fiber during this period allows for a sustained energy uptake and has also shown to have benefits in reducing sow constipation. Feeding fiber in sows comes with several practical limitations. Bulk density of ingredients can complicate logistics at the feed mill. Evaluation of the cost-benefit of dietary fiber on sow lifetime productivity is a lengthy process and can be further complicated by ingredient availability. As we look into the future of fiber research in sows, there is a need to understand the dietary fiber NE contribution in sows as well as the functional value of dietary fiber and how that can impact sow longevity and lifetime productivity, particularly as we transition more to pen gestation. As also discussed in Dr. Petry’s talk, much of this understanding is going to come with further evaluation and characterization of dietary fiber ingredients, both from a chemical and physiological standpoint.

AB Vista’s Dr. Laura Merriman Wraps Up with New Research

Dr. Laura Merriman, swine technical services manager for AB Vista North America, wrapped up the fiber symposium with a discussion on “Current Limitations to Implement Fiber in U.S. Sow and Nursery Diets and Nutritional Strategies to Support an Ideal Fiber Profile.” Like previous presenters, Dr. Merriman also emphasized the challenges with fiber in both sow and nursery programs, largely attributed to our poor understanding of ingredient composition and variation in fiber analysis. Current nutrition reference guides provide some fiber nutrient specifications of ingredients; however, there is limited availability of TDF and NSP values. There is a growing need by nutritionists to better understand fiber and its composition in ingredients, but analysis is quite costly and time-consuming. Technologies such as NIR can provide a quick and inexpensive solution for nutritionists to analyze ingredients and obtain real-time values for both TDF and NSPs.

Regardless, the US has limitations in fiber ingredient availability, feed mill processing, and high cost of specialty fiber ingredients, particularly readily fermentable fiber types. Nutritional technologies, such as a stimbiotic, can provide a cost-effective way to improve fiber fermentation in both the sow and nursery pig. A stimbiotic is a fermentable NSP source that stimulates the establishment of a fiber-degrading and fermenting microbiome, resulting in increased short-chain fatty acid and endogenous enzyme production. In the sow, stimbiotic addition helps increase the level of fermentable and readily available fiber to be used as an energy source for the animal. Addition of 5% sugar beet pulp and a stimbiotic during gestation has shown improvements in piglets born alive and stillborns, particularly in parity 1 females, as well as lactation feed intake. During the peripartum period, supplementing parity 1 sows with >400 g/d of TDF plus a stimbiotic for a minimum of three days prior to farrowing through lactation reduced preweaning mortality by >1.5%. Given that newly weaned pigs have a limited capacity for fermentation and utilization of fiber-rich ingredients, supplementing a stimbiotic can provide a solution to help the piglet rapidly establish a fiber-fermenting intestinal microbiome as early as five days post-weaning. In a recent nursery study, a stimbiotic increased digestibility of protein, energy, insoluble dietary fiber, and total dietary fiber by 7.6%, 8.1%, 42%, and 31% respectively, over a control diet in the first 26 to 28 days. Additionally, a stimbiotic has been shown to improve intestinal barrier integrity, inflammation, and growth in nursery pigs undergoing a health challenge. Using functional feed additives that target a fibrolytic microbiome along with tools to analyze and understand fiber in dietary ingredients can help nutritionists to better utilize fiber in swine diets and provide benefits in animal health, productivity, and performance.

Dietary fiber continues to be a critically important and rapidly growing area of research for the swine industry. This fiber symposium sponsored by AB Vista provided a great opportunity for producers, academic professionals, and industry partners to review and discuss the information currently available in the literature as well as present ongoing research in this area. If you’d like additional information on this scientific fiber forum, AB Vista’s fiber calculator or how to advance your scientific understanding and practical strategies moving forward, please contact nam@abvista.com, www.abvista.com  or scan the QR code.

(L to R): Dr. Spenser Becker, Dr. Nicholas Gabler, Dr. Laura Merriman, Dr. Amy Petry, Dr. David Rosero