Fiber in Animal Nutrition

Fiber in Poultry Nutrition 38 diet. Due to the higher 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 nutri- ent digestion in the intestine. Furthermore, there are clear indications that diets high in insoluble fiber are preventive of cannibalism outbreaks in laying hens. In recent studies in broiler breeders it could be demonstrated that insoluble fiber has a positive impact on performance in terms of laying percentage (Farran and Akilian, 2014) as well as on animal welfare (Nielson et al. 2011). Soluble fibers do not carry this positive ef- fect.They depress the digestibility of protein, starch and fat due to their negative impact on digesta viscosity. For more details on the fiber classification and the fiber analysis I would like to refer to chapter 1. 3.3 Selecting the right fiber source As described in detail in the chapter above insoluble fibers are the far better fibers for our birds compared to soluble fibers. Our traditional fiber sources like wheat bran deliver soluble and insoluble fibers. Additionally with 10% crude fiber they are quite low in fiber and some usually carry massive mycotoxine problems. Typical fi- ber level of our traditional sources as well as the proportion soluble / insoluble fiber components are shown in the annex table 28. Some traditional fiber sources like oat hulls are quite high in insoluble fibers but unfortunately they are not available onmany markets and they are often highly contami- nated with mycotoxins as well. A solution for this problem could be an insoluble crude fiber concentrate (CFC). These functional fibers are constantly available and free of mycotoxins. CFC describes fiber-products with a cru- de fiber content of at least 60%. This high content is mostly achieved by concentration processes, which can be of physical or thermo- mechanical nature. CFCs are usually based on a lignocellulosic or a cellulosic fiber. Main differences beteween CFCs and com- mon fiber sources are: • crude fiber content >60%; • without mycotoxin risk • do not bind nutrients • stimulate the intestinal villi; • increase enzyme activity; • high swelling- and water binding capacity (4–8 g H 2 0/g crude fiber concentrate). Soluble fiber Insoluble fiber • Lowers intestinal passage rate • Reduces digestion of fat, protein and starch • “Prebiotic” effect • Energy source for monogastric animals • Affects viscosity of the digesta • Mainly fermentable parts • Reduces dry matter of faeces • Binds nutrients (pectin) • “Structurising” fiber • Improves starch digestibility • Increased intestinal passage rate • Poorly fermentable • Stimulation of intestinal villi • No energy source for young monogastrics • Increases dry matter content of faeces • Prevents cannibalism Table 12: Effects of soluble and insoluble fiber sources in poultry nutrition © ERLING Verlag