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Feed interventions and skatole deposition

Jensen, Rikke Lassen (2012) Feed interventions and skatole deposition. Masters thesis, University of Copenhagen, Department of Large Animal Science. .

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Summary

Skatole produced in the large intestine of the pig and the testicular steroid androstenone are the main substances contributing to boar tainted meat from entire male pigs. Boar taint decreases the quality of the meat and is not accepted by consumers. Until now boar taint has been avoided by castrating male pigs. Surgical castration reduces lean meat percentage, growth rate and feed efficiency, and it causes pain to the animal. This constitutes a problem in relation to productivity and welfare. Different attempts on avoiding surgical castration were either not fully effective, not accepted by the market, or they have a long time horizon for implementation. However, when focusing on the effect of feed interventions on boar taint, previous studies have showed a reducing effect through reduced skatole production in the large intestine after a one week application period. Skatole is produced from the microbial fermentation of L-tryptophan in the large intestine. In the literature it is well documented that skatole production in the large intestine is positively correlated with skatole deposition in adipose tissue. Moreover skatole production can be decreased by adding non-digestible and easy fermentable carbohydrates to the feed. However, little is known about skatole producing bacteria from the large intestine of pigs, and how these bacteria can be affected.
This thesis reviews skatole production and metabolism in the pig, and how skatole production can be reduced by affecting the microbial production of skatole in the large intestine. A skatole producing bacterium SK9 K4 was isolated from the gastrointestinal tract of pigs. No such bacterium has previously been described. The bacterium was characterised by 16S RNA sequencing, gram stain, analysis of DNA G-C content, cellular fatty acids composition and DNA hybridisation with closely related bacteria. The fermentation of different carbohydrate sources, the growth pattern, the production of organic acids and the skatole production were studied in vitro.
The production of skatole in the large intestine was correlated with skatole deposition in adipose tissue. Skatole production could be reduced when adding a minimum of 20 % raw potato starch or 9 % inulin to the feed. The problem concerning deposition of skatole in adipose tissue seems to be solved through the introduction of feed interventions. However high concentrations of androstenone deposited in adipose tissue remains a challenge. Thus, the feed interventions were not fully effective against boar taint.
SK9 K4 was described as cells being strictly anaerobic, occurred singly or in pairs and were gram positive. It was identical with an Olsenella sp. strain isolated from the rumen, an uncultured Olsenella sp. clone isolated from sludge and an uncultured bacterium colon isolated from the oral cavity. Moreover SK9 K4 was closely related to Olsenella uli, Olsenella profusa, Olsenella umbonata and Atopobium parvulum. SK9 K4 and O. uli produced skatole from idole-3-acetic acid but not from L-tryptophan. The major fermentation products were lactic acid together with acetic acid and formic acid. SK9 K4 was not able to ferment raw potato starch, inulin and raw corn starch. Thus, when feeding resistant starch or inulin, the growth of skatole producing bacteria might be reduced followed by a reduced ability to produce skatole. The characterisation of a skatole producing bacterium isolated from the gastrointestinal tract of pigs gives the opportunity to further study the bacterium in vivo. Studies should be conducted to investigate the effect of a control diet compared to a diet added a non-digestible and easy fermentable carbohydrate on the growth of SK9 K4 in the large intestine of the pig.

Summary translation

Skatol produktion i grisens tyktarm og kønshormonet androstenone er de primære stoffer, der bidrager til kød fra hangrise med ornelugt. Ornelugten nedsætter kvaliteten af kødet og er ikke accepteret af forbrugerne. Hidtil er ornelugt undgået ved at kastrere hangrise. Kastration reducerer kødprocenten, tilvæksten og fodereffektivitet og forårsager smerte til dyret. Dette udgør et problem i forhold til produktivitet og velfærd. Forskellige forsøg på at undgå kastration har vist sig ikke at være fuldt ud effektive, blev ikke accepteret af markedet eller havde en lang tidshorisont. Fokuseres der på virkningen af foder interventioner på ornelugt, har tidligere undersøgelser vist en reducerende effekt gennem reduceret skatol produktion i tyktarmen efter en periode på en uge. Skatol er et produkt fra den mikrobielle fermentering af L-tryptophan i tyktarmen. I litteraturen er det veldokumenteret, at skatol produktion i tyktarmen er positivt korreleret med skatol aflejring i fedtvæv. Desuden kan skatol produktion reduceres ved tilsætning af ikke-fordøjelige og let fermenterbare kulhydrater til foderet. Der er dog begrænset viden om skatol-producerende bakterier isoleret fra tyktarmen hos svin, samt hvordan disse bakterier kan påvirkes.
Dette speciale undersøger ved en litteraturgennemgang skatol produktion og metabolisme hos svin og hvordan skatol produktion kan reduceres ved at påvirke den mikrobielle produktion af skatol i tyktarmen. En skatol-producerende bakterie SK9 K4 blev isoleret fra mave-tarmkanalen hos grise. En sådan bakterie er ikke tidligere blevet beskrevet. Bakterien blev karakteriseret ved 16S RNA sekventering, gram farvning, analyse af GC indhold i DNA, den cellulære fedtsyrere sammensætning og DNA hybridisering med nært beslægtede bakterier. Fermentering af forskellige kulhydrat kilder, vækst, produktion af organiske syrer og skatol produktion blev undersøgt in vitro.
Produktionen af skatol i tyktarmen var korreleret med skatole aflejring i fedtvæv. Skatol produktionen kunne reduceres ved at tilsætte minimum 20 % rå kartoffel stivelse eller 9 % inulin til foderet. Udfordringen med skatol aflejring i fedtvævet lader til at kunne løses gennem foder interventioner. Dog er aflejring af høje koncentrationer androstenon i fedtvæv fortsat en udfordring. Derfor var de fundende foder interventionerne ikke fuldt ud effektive mod ornelugt.
SK9 K4 blev beskrevet som celler, der er strengt anaerobe, forekom enkeltvis eller parvis og var gram positive. Bakterien var identisk med en Olsenella sp. stamme isoleret fra vommen, en ukultiveret Olsenella sp. klon isoleret fra slam og en ukultiveret bakterie klon isoleret fra mundhulen. Desuden var SK9 K4 nært beslægtet med Olsenella uli, Olsenella profusa, Olsenella umbonata og Atopobium parvulum. SK9 K4 og O. uli producerede skatol fra idole-3-eddikesyre, men ikke ud fra L-tryptophan. De store fermenteringsprodukter var mælkesyre sammen med eddikesyre og myresyre. SK9 K4 var ikke i stand til at fermentere rå kartoffelstivelse, inulin og rå majsstivelse. Ved fodring med resistent stivelse eller inulin, er det derfor muligt at væksten af skatol producerende bakterier reduceres, efterfulgt af en reduceret skatol produktion. Karakteriseringen af en skatol producerende bakterie isoleret fra grisens tarmsystem giver mulighed for yderligere at studere bakterie in vivo. Undersøgelser bør udføres med henblik på at undersøge virkningen af en kontrol diæt sammenlignet med en diæt tilsat ufordøjelige og let fermenterbare kulhydrater på væksten af SK9 K4 i tyktarmen.

EPrint Type:Thesis
Keywords:NO CAST, skatol, androstenon,castration
Subjects:"Organics" in general
Animal husbandry > Health and welfare
Animal husbandry > Production systems > Pigs
Research affiliation: Denmark > AU - Aarhus University
Denmark > Organic RDD > NO-CAST
Denmark > AU - Aarhus University > AU, DJF - Faculty of Agricultural Sciences
Denmark > KU - University of Copenhagen
Related Links:http://www.icrofs.org/Pages/Research/organicrdd_nocast.html
Deposited By: Madsen, Academic employee Mette Graves
ID Code:22058
Deposited On:27 Dec 2012 09:31
Last Modified:27 Dec 2012 09:31
Document Language:English
Status:Published
Additional Publishing Information:The thesis has been carried out in cooperation with Department of Animal Science - Immunology and Microbiology Aarhus University.

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