Einflüsse von Nicht-Stärke-Polysacchariden des Futters und von Nematodeninfektionen auf Verdauungsprozesse bei wachsenden Junghennen (English shop)

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Chickens kept in floor and outdoor husbandry systems are at risk from nematode infections. For this reason, among other things, possibilities are being sought for the preventive control of infections by means of naturally occurring feed constituents that can influence digestive processes and thus also the developmental conditions of nematodes in the intestinal tract. In the present study, the effects of non-starch polysaccharides (NSP) in the feed and of nematode infections on digestive processes in growing pullets were investigated. Three feed mixtures were used: basal mixture (K), K plus pea hulls as a source of insoluble NSP (U-NSP), and K plus chicory root meal as a source of inulin-rich soluble NSP (L-NSP). The supplements of pea hulls and chicory root meal each amounted to 100 g/kg K. The study comprised two experimental series with either Ascaridia galli or Heterakis gallinarum infections. Each experimental series consisted of three experimental runs. In each experimental run, 100 Lohmann LSL pullet chicks were supplied ad libitum with the experimental feed mixtures from the 1st day of life until the 8th week of life (WoL) in separate pens bedded with wood shavings. In the 3rd WoL, each feeding group was subdivided into 2 × 50 birds, and one of these subgroups was infected by a single oral intubation with 250 or 200 embryonated eggs of the small intestinal parasite A. galli or the large intestinal parasite H. gallinarum, respectively. In the 8th WoL, 6 birds from each of the 6 groups were transferred to metabolism cages in each experimental run in order to measure nutrient utilisation after five-day pre-feeding and collection periods. During these metabolism periods, the feed mixtures were used with the addition of titanium dioxide (TiO2). At the end of the metabolism periods, the birds were slaughtered and the small intestines were removed to determine digesta quantities. The feedstuffs, excreta and small intestinal digesta were analysed for dry matter (DM), insoluble NSP, soluble NSP, inulin and TiO2. In addition, neutral detergent fibre (NDF) and nitrogen (N) were analysed in feedstuffs and excreta. In one experimental run each with A. galli and H. gallinarum infection, the extract viscosities of the small intestinal digesta were measured in each experimental group in 10 birds that had remained in floor housing until the 12th WoL. The study yielded the following results: 1. The development of H. gallinarum was promoted by the supplementation of chicory root meal, whereas the development of A. galli remained unaffected by the feeding. For the digestive parameters examined, no substantial interactions occurred between the experimental factors “feeding” and “infection”. 2. Digestibilities derived by means of the collection method and the indicator method agreed very well for soluble NSP and for inulin when the birds were supplied with supplements of soluble NSP, but less well when supplied with K or U-NSP and generally for insoluble NSP. When the collection method was applied, insoluble NSP were recorded as excretions that exceeded the amounts determined as consumed, owing to unavoidable cumulative feed spillage losses. With the collection method, this led to physiologically unrealistic digestibilities of these structure-forming fibre fractions. 3. The amounts of small intestinal digesta dry matter were increased by the NSP feed mixtures. The extract viscosities of the small intestinal contents were lower than in the birds supplied with K when the NSP mixtures were fed – in the experimental runs with A. galli infections with both NSP mixtures, and in the experimental runs with H. gallinarum infections in connection with L-NSP. 4. Soluble NSP were digested in larger amounts when the birds were supplied with U-NSP compared with feeding L-NSP, and in smaller amounts by A. galli-infected compared with non-infected birds. Both infections reduced the digestibility of inulin. Insoluble NSP were only slightly digestible in both experimental series when the birds were supplied with the NSP mixtures (< 10 % according to the indicator method). The infections had no effect on the digestibility of this NSP fraction. The contents of soluble and insoluble NSP as well as of inulin in the small intestinal digesta and excreta, related to indigestible TiO2, show that soluble NSP and inulin were digested to a considerable extent in the large intestine, while insoluble NSP were largely indigestible. 5. N retention was increased compared with the other feeding groups only in the experimental runs with H. gallinarum infections when U-NSP was supplied. The infections had no effect on N retention. The results permit the conclusion that pea hulls as a carrier of insoluble NSP and chicory root meal as a carrier of inulin-rich soluble NSP, at the proportions included in the feed mixture here, offer no possibilities for supporting the digestive processes in growing pullets in terms of intestinal parasite defence and improved performance under parasite infestation.