Insoluble fiber – An essential nutrient for poultry

In the past decades nutritionists did not pay attention to fiber in poultry feed formulations. Step by step the researcher as well as the industry realizes the importance of fiber for poultry. The use of fiber in poultry has been and still is a major research topic at universities around the globe. This paper will give an overview on the basics in fibers in poultry nutrition with a special focus on broiler breeders.

Dr. Manfred Pietsch
Head of Animal Nutrition Department
JRS Germany

Dietary fiber has been described as the skeletal remains of plant cells in diets that are not digested by animal digestive enzymes. Fibers constitute a significant part of all plant feedstuffs. The variation in the amount and structure is large between different plant materials. The structure has a significant impact on the physiological function of fiber; therefore it makes sense to classify them.

A main distinctive feature amongst different fiber sources is the solubility. Vegetable roots and fruits like apple, orange and sugar beet deliver mainly soluble fiber (i.e. pectin) while all kinds of bran deliver more insoluble (i.e. cellulosic) fiber. A quite interesting product group that has been researched intensively in the past 10 years are the crude fiber concentrates based on lignocellulose. They deliver by definition at least 60 % crude fiber which is insoluble.

There is some evidence that insoluble fibers have a positive effect on selected parameters. The digestibility of starch is higher and digesta passage rate faster when a moderate level of insoluble fiber is present in the diet. Due to the faster passage rate there is less accumulation of toxic substances in the intestinal tract. The effect of insoluble fiber on gut functions stems from its ability to accumulate in the gizzard, which seems to regulate digesta passage rate and nutrient digestion in the intestine. Furthermore, there are clear indications that diets high in insoluble fiber are preventive of cannibalism outbreaks in laying hens and breeders. On the other hand soluble fibers depress the digestibility of protein, starch and fat due to their impact on digesta viscosity.

There are plenty of trials showing that insoluble fibers improve the litter quality in broilers and layers significantly. Farran from the American University of Beirut observed a significant reduction in litter moisture in broilers due to the use of an insoluble crude fiber concentrate compared to wheat bran. In this corn soya formulation 0.8 % of insoluble crude fiber concentrate (ARBOCEL®, JRS Germany) replaced 0.8 % of wheat bran. Barwary from the La Trobe University in Australia confirmed these positive effects of insoluble crude fiber concentrate on the litter quality in layers in their trails.

There is limited information available on the effect of fiber on litter quality in broiler breeders. Nelson et al. 2010 from Aarhus University in Denmark compared the effect of three different feed formulations on selected health related parameters in broiler breeders. They evaluated a low fiber control formulation (Total Dietary Fiber 3,03 %) and two high fiber formulations (TDF 4,19 and 3,75 %). The two high fiber formulations differed mainly in the ratio of soluble/insoluble fiber. One was high in insoluble fiber (insoluble NSP 90% of total NSP) and the other contained more soluble fiber (insoluble NSP 79% of total dietary fiber). The formulation containing high fiber with an elevated proportion in soluble fibers caused significant problems with wet litter. Results are shown in Table 1.

It can be concluded from this trial that high fiber levels can help to control the litter moisture, but the fiber needs to be insoluble. Soluble fiber has adverse effects.

There is evidence that the positive impact of insoluble fibers on the wet litter scenario is related to the impact of the insoluble fibers on the transit period. Insoluble fiber speeds up the transit of the digesta in the small intestestine. Thus harmful bacteria cannot colonize and produce endotoxines, which often cause a release of water into the lumen.

Beside the management, the genetics and the lighting program dietary factors are discussed as a cause for cannibalism. Low protein diets, low sodium intake as well as a lack of some essential amino acids are seen as a cause of cannibalism. More and more trials show the importance of an adequate level of insoluble fiber in the formulations to prevent cannibalism.

A trial at the University of New England in Australia demonstrated that the inclusion of mill run as an insoluble fiber source significantly affect the cannibalism related mortality in layers. During the laying stage the mortality in the control group fed the wheat based feed (2.9 % crude fiber) was 29%. By using mill run the mortality was significantly reduced down to 14%. Similar results have been observed at the University of Stuttgart-Hohenheim, Germany. Here an insoluble crude fiber concentrate resulted in a reduction in feather pecking in layers from 10.8 % in the control group to 2.9% in the crude fiber concentrate-Group. In this trial the insoluble crude fiber concentrate caused better feather conditions as well (Table 2).

Grashorn and his group from the University of Hohenheim, Germany did interesting trials that help to explore the mode of action of fibers on the cannibalsm scenario. They established that strains with high incidence of feather pecking ingest more feathers than a strain with low incidence of feather pecking. Harlander discovered that feathers have the same effect on the intestinal tract as insoluble fiber, which is the acceleration of the intestinal transit time. A logical conclusion is that the animals ingest the feathers to overcome a deficiency of insoluble fiber.

For sure this postulated mode of action for fiber deficiency related feather pecking and cannibalism is valid for broiler breeders as well. In broiler breeders there is evidence that the occurrence of cannibalism and feather pecking caused as well by the restricted feeding practice.

The positive impact of insoluble fibers on the performance of broiler breeders has been shown by Prof Farran and his group from the AUB in Lebanon. They investigated the impact of an insoluble crude fiber concentrate on selected performance related parameters in breeders. This trial was published at the EPC meeting in 2014 in Norway. The trial design as well as the results are summarized in table 3. Corn-soybean meal diets containing 0.8% wheat bran (control) were formulated to meet the specifications of the breeders. The trial diets containing 0.8% crude fiber concentrate were reformulated to have the same specifications as the control diets in terms of energy, crude protein, and other essential nutrients.

Taking the increased number of hatching eggs and the improved hatchability into account inclusion of 0,8 % crude fiber concentrate in the trial feed resulted in massive increase in sellable chicks per hen housed. The authors calculated an additional net profit per hen housed of 2.3 US dollars in 6 months based on the current price of the crude fiber concentrate used in the trial diets and the price of a day old bird.

The impact of insoluble fiber on health and performance of broiler breeders during feed restriction has been well summarized in Jacky Michards paper published in 2011 (Hubbard Technical Bulletin, 10/2011). He promotes the use of low density diets which can be achieved by diluting the feed formulation with insoluble fiber sources. According to the author internal Hubbard field trials have shown some very beneficial effects by applying this approach:
• Prolonged feed clean up by 5-15 minutes in rearing and 30 – 90 minutes in the laying stage
• Better flock uniformity
• Calmer birds which prevents feather pulling
• Easier to control litter quality (dryer litter)
• Livability in rearing and production is improved

The commercial restricted feeding program of broiler breeders has a major negative effect on welfare, as the birds are continuously hungry. A main topic in breeder nutrition is to reduce this hunger stress because it contributes to the development of feather pecking/ cannibalism, wet litter as well as problems with flock uniformity. A good measure of the level of hunger stress is the feed clean up time. In situations with reduced hunger stress the feed clean up time will be increased, with other words the birds eat slower.

The impact of insoluble fiber on feed clean up time and flock uniformity was evaluated in a field trial in Brazil. A total of 80 000 Cobb 500 breeders were involved in this trial. They put 40 000 birds on a commercial breeder formulation and 40 000 on exactly the same formulation with the difference that 0,8 % wheat bran were replaced by 0,8 % of an insoluble crude fiber concentrate (ARBOCEL, JRS Germany). They evaluated feed clean up time as well as flock uniformity during the trial period from week 5 to 20.

Figure 1. Weight development of roosters till week 20 in control group

The feed consumption time was prolonged up to 24 % due to the use of the insoluble crude fiber concentrate. This confirms the observations of J. Michard from Hubbard. As a consequence of the prolonged feed clean up time the flock uniformity was significantly improved.

Weight control is an important issue in roosters as well. If they exceed the standard weight as defined by the genetic companies there is a negative impact on semen quality and the birds get very aggressive as well. As there are even more negative aspects of rooster overweight the weight control of roosters should be a major concern in the poultry house. The impact of insoluble fiber on the weight of roosters has been evaluated as well in the above mentioned Brazilian field trial. The results are shown in figure 1 and 2.

Figure 2. Weight development in roosters till week 20 in the trial group with 0,8 % insoluble crude fiber concentrate ARBOCEL

Figure 1 shows the weight development of the roosters in the control group. Their average weight is clearly above the target weight while the birds in the trial group (0,8 % ARBOCEL) do match the target weight as given by the genetic company (Figure 2). It can be concluded from this trial that insoluble crude fiber concentrates are a good tool to control the weight of roosters.

Since around 10 years the use of fibers in poultry feed formulations is researched very intense. Latest research demonstrates that it is the insoluble fibers that cause a positive impact on heath and performance in poultry. Latest field and university trials have been summarized in this paper. In summary it has to be pointed out that insoluble fibers impact parameters like wet litter, cannibalism and feather pecking as well as performance positively in all poultry species due to their physicochemical characteristics. Additionally the insoluble fiber promotes satiation effects in restricted fed animals like broiler breeders.

About Dr. Manfred Pietsch
Manfred Pietsch graduated in human nutrition (Dipl. oec. troph) from the Justus-Liebig University in Giessen, Germany in 1992 and received doctor’s degree at the Institute of Animal Nutrition, Justus-Liebig-University in 1996. He worked as a product and poultry application manager for several feed additive suppliers from 1996 to 2008.
Pietsch has been poultry application manager and head of animal nutrition department in JRS, a supplier for insoluble functional fiber to the feed industry since 2008. In his function as poultry application manager; Dr. Pietsch published more than 20 reviewed articles on the fiber issue in poultry nutrition in specialized journals like Asian Poultry Magazine, International Poultry Production and Poultry Talk. Additionally; Dr. Pietsch is co-author of numerous original articles published in scientific journals.