Fachbereich Veterinärmedizin



    Untersuchungen zur Wirkungsweise einer Xylanase im Verdauungstrakt von Masthühnern (2002)

    Hübener, Katrin
    Berlin: Mensch & Buch Verl., 2002 — 148 Seiten
    ISBN: 3-89820-412-X
    Institut für Tierernährung

    Königin-Luise-Str. 49
    Gebäude 8
    14195 Berlin
    +49 30 838 52256

    Abstract / Zusammenfassung

    An automatic milking system (AMS) has been implemented June 1997 at the animal breeding and testing facility within the veterinary faculty of the university of Munich.
    A mixed herd of cows consisting of the races Deutsche Holsteins and Deutsches Fleckvieh has been milked with the new system.The cows become familiar surprisingly fast to the new milking system during the period of adaptation and with an appropriate treatment.
    Compared with earlier and with the group being milked as before in a conventional milking stand the animals of the test group ehave more quiet, sociable and friendly.
    The average occupation is 51, 59 cows within the evaluation period, the average lactation level is 166, 4 lactation days.Only cows of the race Deutsches Fleckvieh yielded a performance increase of 5,342 %. The yield of Deutsche Holsteins decreases 3,513 % in the AMS related to the yield in the conventional stand.The persistence of yield during the whole lactation period is better with Fleckvieh in the AMS than in the stand, vice versa with Deutsche Holsteins.It makes no difference in their visiting frequency for the Deutsche Holsteins whether they used a conventional system before or the AMS from the very beginning exclusively.The Fleckvieh cows having been milked before in the tandem use the AMS more frequently than those using the AMS only.The comparison of lactations of both races shows for both races the maximum daily average volume in the second lactation (DFV: 20, 316 kg, DH: 24, 393 kg). The activity is focused for the Deutsche Holsteins in all parts on the first section of all lactations investigated.The maximum daily yield per cow, the maximum single milk volumes and the maximum visiting frequencies fall always into the first section of the lactations two, three and four.The most frequent refusals fall also into the first section, but during the lactations one, two and three. The most frequent unsuccessful visits fall all together into the period of the fourth lactation or into a higher order.The race Deutsches Fleckvieh shows a concentration of their activity on individual lactations. Their visiting frequency decreases 23,5 \%, starting from the first two lactations up to the subsequent ones. The most frequent refusals are scored in the first two lactations as well, but for animals within higher numbers of lactations a decrease of 50 % in the visiting frequency is scored.These results are not consistent with the daily milk yield per cow of this race. The maximum daily milk yield per cow is recorded in the second lactation for both races, the second highest daily yield is recorded in the third lactation.With a small occupation the cows visit the AMS during their preferred milking times. A three peak activity pattern is observed. An increasing occupation esults necessarily in an even distribution of the activity pattern. The peak of visits appears between 18.00 and 19.00 o"clock, the valley of visits appears between 4.00 and 5.00.The visiting frequency is equal for both races with a relative small size of the herd. The visiting frequency decreases in both races with increasing size of the herd, but more with DH cows than with DFV-cows. The DFV race represents itself more useful for the automatic milking than the DH race in a mixed herd. The Fleckvieh cows prove to be more robust and less sensitive during high occupation. The visiting frequency does not decrease as much as with the Deutsche Holsteins.The elevation of comfort for the cows by an AMS is only provided with free circulation.The discrepancies among the statistical evaluation of the AMS management system and personal documentation of the data concerning the degree of load of the AMS could not be explained.999:021.002:The utilization of NSP (non-starch-polysaccharide)-degrading enzymes is in wide use because of the increase in performance, although relatively little is known about its method of action. During the implementation process the effects of xylanases in the digestive tract of chickens are examined.
    In particular, the results produced from the interaction with the intestinal microflora are examined here.Diverse parameters dependent on the supplementation of xylanase, NSP-content and fat source respectively were included with broiler chickens of the "Lohmann Meat" line in three experiments.In the first experiment a ration containing small amounts of NSP (76% corn, 17% isolated soyaprotein and NSP-rich rations (15% rye, 61% wheat, 14 % isolated soyaprotein) were fed with and without xylanase supplementation (400g/t Zy 68 ). Live weight increase and feed to gain ratio were examined up to the 35th day of life, as well as digest viscosity, length and weight of the intestine, colony count of chosen groups of adhered intestinal acteria as well as NSP-degradation by culture supernatant from isolated intestinal bacteria on the 7 th and 28 th day of life; contents of short chain fatty acids in digest supernatants, growth of adhered intestinal bacteria in the presence of diverse carbohydrate sources and the activities of chosen enzymes in digest supernatants (xylanase, ß-glucanase, bile acid hydrolase) on the 28 th day of life in addition to bacterial growth capacity of digest samples in selective and minimal fluid media on the 42nd day of life of the chicken.The rations of the second experiment were administered as a starter ration until the 14th day of life with 61% triticale and 26% soya extraction meal and in the main feeding period with 64% triticale and 22% soya extraction meal each with and without xylanase supplementation (200 g/t Zy 68).
    Activity of (xylanase, ß-glucanase, bile acid hydrolase and lipase) was determined in the digest supematant of five intestinal sections on the 8 th, 15 th , 22nd , 29th and 36th day of life.In the third experiment the influence of diverse fat sources were to be examined in addition to xylanase supplementation. Rations with 48% wheat, 24% rye, 18% isolated soyaprotein and 4,0% soya oil or 4,7% tallow respectively each with and without xylanase supplementation (200g/t Zy 68) were fed to four feed groups. The activity of xylanase, ß-glucanase, bile acid hydrolase and lipase in the digest supernatant of four small intestine sections were measured on the 3rd, 5th , 7th, 1th, 13th and 20th day of life. In addition, the bacterial growth from digest samples jejunum) were examined in diverse fluid media with and without bile salt additive (taurocholate).
    The xylanase supplementation to the feed is capable of influencing nearly all essential factors upon which intestinal microflora is dependent, whereby there is a high potential to alter the microflora. The digest viscosity sinks, through which the speed of passage and the digest mixing rises, the nutrition supply and the intestinal surface changes and the size of the intestinal convolute is lessened.Changes to the intestinal microflora through the xylanase supplementation. The examination of the microflora (colony counts, volatile fatty acid content) shows a reduction of the intestinal tract population density under the influence of xylanase supplementation with most of the examined bacterial groups (anaerobic bacteria, enterobacteria, gram-positive cocci), whereby a smaller potential of pathogenic microorganisms can develop. The reduction of population density is probably due to the increased speed of passage of the digest and altered adhering conditions.
    The lactic acid bacteria take on a special position that have not been reduced by enzyme supplementation at least in the forth week of life; their relative spread can have a positive effect on the chicken.Influence of NSP-hydrolyzing enzymes in the intestine by xylanase supplementationNSP-oligomeres are produced in the digestive tract by xylanase supplementation. Through this parts of microflora which are capable of utilizing these fragments can be stimulated. As the bacterial growth capacity from digest samples in the presence of diverse carbohydrates shows, this happens in more proximal areas of the intestine than would be the case without added xylanase. The microflora modified by xylanase supplementation degrades not only arabinoxylan easier than the microflora of the unsupplemented groups does, but there is also degradation activity of other NSP.
    This could be shown by the increase of ß-glucanase, activity in the digest supematant as well as the correlation of NSP-degrading in the individual isolated bacteria.
    All ofthese factors point to the conclusion that supplementing xylanase as a monopreparation can also lead to an increase in the degrading of other NSP, figuratively portrayed by a kind of "domino effect" - which could either be a result of a selective promotion of corresponding bacterial groups, or due o substrate dependant enzyme induction.Positive influences of xylanase supplementation on fat digestion.
    The improvement of fat digestion by xylanase supplementation is due to the alleviated blending of the digest. This is shown in the individual experiments that the addition of xylanase can take effect more strongly in the pancreas lipase in areas further from the situated small intestine samples. This makes for a quicker division of triglyceride and a longer absorption route.On the other hand there is decreased deconjugation of conjugated bile acids by acterial formed bile acid hydrolase. Conjugated bile acids make an effective fat absorption possible through playing a fundamental role by emulsifying effect and micelle formation. The first two experiments proved a decrease in the bacterial formed bile acid hydrolases when xylanase was added, especially in the proximal small intestine area, where the majority of the lipid absorption takes place. The xylanase in the feed probably causes a repression of the bacterial groups, which are produce bile acid hydrolase. This is also shown by the in vitro-incubation of digest samples when bile acid (taurocholate) is added: the addition of xylanase to the feed led to a less bile acid resistant intestinal flora in the growth of the anaerobic bacteria as well as in the growth of enterobacteria in the jejunum.
    This study will confirm the already known influence mechanisms and show more new explanations in the complex effective structure of NSP-hydrolyzing enzymes.