Fiber in Animal Nutrition

37 3.1 Introduction The use of dietary fiber (crude fiber) in poultry feed formulations is often a controversial subject among nutrition specialists. On the one hand international organiza- tions like ISA or Lohman consider crude fiber an essential component in layer for- mulations. ISA (2007) for example stated in their feeding guidelines “the presence of insoluble fiber appears indispensable, causing an increase in gizzard size, improved starch digestibility and limiting feather pecking”. Robert Pottgüter (2008) the nutritionist at Lohman published similar statements. On the other hand many nutritionists still avoid the use of fiber as most fiber sources do not deliver sufficient energy for monogastric animals. These fiber sources dilute formula- tions. This is not the aim of the nutritionists formulating poultry diets – where space in the diet costs money. Additionally the tradi- tional fiber sources are associated with some negative attributes like high plate counts, and mycotoxin contamination. One reason for fiber in nutrition being controversial might be the fact that different fibers have different effects on the digestive system and some other parameters. A distinctive characteristic for different fibers is solubility, which seems to impact performance and health of the birds. Most fiber sources are by-products of the food manufacturing industry – therefore we preferably use those fiber sources which are available in the region, and not those, which are potentially best for our animals. The key question is: could we get a better performance or a better health status in the birds if we systematically use soluble or insoluble fiber sources instead of using the locally available by-products? To discuss this topic is one of the main aims of this book chapter. In this context functional fibers will be discussed in detail and insoluble crude fiber concen- trates (CFC) will be introduced as suitable alternative. 3.2 Fiber classification Dietary fiber has been described as the skele- tal remains of plant cells in diets that are not digested by animal digestive enzymes. Fibers constitute a significant part of all plant feed- stuffs.The variation in 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. Amain 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 kind of cereal brans delivers a high percentage of insoluble fiber. Advantages and disadvantages of soluble and insoluble f iber sources are shown in table 12. There is some evidence that insoluble fibers have a positive effect on selected parameters in poultry production as reviewed in the paper from Hetland et al. 2004 which was published in the World’s Poultry Science Journal.Thus, digestibility of starch is higher and digesta passage rate faster when a mode- rate level of insoluble fiber is present in the Fiber in Poultry Nutrition Manfred Pietsch © ERLING Verlag