Evaluation of in-feed additives in early-weaned pigs study of the XTRACT(tm), a plant extracts based additive

El principal objectiu daquest treball es avaluar els efectes dun additiu comercial XT (5% carvacrol, 3% cinamaldehide, 2% oleoresina d capsicum) sobre els rendiments productius i diferents parametres de la fisiologia digestiva del garri deslletat precocment. Un altre objectiu daquest treball es avaluar les possibles interaccions del XT amb altres ingredients, nutrients i additius de la dieta. Aquest treball sha dentendre com a part dun ampli pla de recerca multicentric organitzat per la companyia Pancosma. En concret hem avaluat i) lefecte del XT als parametres mencionats depenent del nivell i font de proteina, ii) la possible interaccio entre lXT i lacid formic, i la comparacio de lefecte del XT amb laccio de lavilamicina i el butirat sodic. Finalment, despres de tres anys de collaboracio i donat linteres de la companyia en desenvolupar nous productes basats en extractes de plantes, hem desenvolupat un metode in vitro per testar el poder antimicrobia dun ampli ventall de substancies derivades de plantes. Al treball in vitro, el nostre objectiu ha sigut desenvolupar un metode molt simple pero realista, utilitzant el contingut de diferent trams del tracte intestinal, obtingut dels porcs sense cap modificacio, i incubant-lo curts periodes de temps. Resultats productius Els resultats productius son molt variables entre experiments. Aquestes variacions son degudes probablement a lus de diferent installacions, edats i estats de salut dels animals i la diferent composicio de les dietes bassals. Mesures fisiologiques i fisiques La digestibilitat ileal i rectal i el pH en les diferents part del tracte gastrointestinal shan estudiat de manera sistematica a les tres proves in vivo pero no shan obtingut resultats consistents. Tanmateix, la inclusio de extractes de plantes a la segona prova va provocar un alentiment del buidament gastric realcionat amb un augment del pH de lestomac. Poblacions microbianes El resultat mes consistent de tots els obtinguts es laugment de lactobacillus amb la inclusio del XT a les dietes. Malauradament, la rellevancia daquest augment no esta gens clara perque no va tenir relacio directa amb cap benefici productiu. La inclusio del XT ha afectat tambe altres parametres microbians: la concentracio de bases puriques i els perfils dacids grassos volatils. Aquest resultats no son molt consistents i de vegades contraris. Parametres epitelials Shan estudiat els efectes del XT a lestructura epitelial pero una vegada mes els resultats son molt variables depenent de la prova. De totes maneres queda clar que lXT exerceix una gran influencia sobre certs parametres immunes del epiteli, i shan de continuar investigant amb tecniques mes especifiques. Estudis in vitro El metode in vitro sha utilitzat amb exit pe compara diferents additius. Les variacions de fermentacio in vitro no nomes depenen del additiu utilitzat, sino tambe de ledat de lanimal i de la part del tracte gastrointestinal utilitzada don sobte linocul. Aquestes variacions shan danalitzar amb deteniment. Daquests estudis podem concloure que les dosis comercials de XT no presenten efectes antimicrobians directes sobre les poblacions microbianes estudiades (lactobacillus i enterobacterias). Utilitzant el contingut de jeju com inocul, es necessiten dosis properes a 10000 ppm per obtenir efectes antimicrobians. Daltre banda, amb dosis mes baixes de les substancies pures saconsegueixen efectes similars. Aquestes dosis varien entre 500 i 3000 ppm de carvacrol i cinamaldehid, depenent de la part del tracte gastrointestinal estudiada. Amb tots els productes, la dosis minima necessaria per inhibir la fermentacio es sempre menor amb el contingut del jeju. _________________________________________________ The main objective of this PhD dissertation is to evaluate the effects of the commercial additive XT (5% carvacrol, 3% cinnamaldehyde, 2% capsicum oleoresin) on productive performance and on different parameters of normal digestive physiology of the early weaned pig: digestibility, pH, epithelial structure, bacterial populations and metabolic activity. It is also an objective of this work to evaluate possible interactions of XT with other ingredients, nutrients and additives included in the diet. This work must be understood in a broader multi-centric research plan organized by the company Pancosma. In particular, the experiments here presented evaluate i) the effects of XT on the above mentioned parameters depending on the CP level and source, ii) the possible interaction between XT and formic acid, and finally the comparison of the effects of XT with the action of avylamycin and butyrate. After three years of collaboration and given the interest of the company in developing new products based on plant extracts, we developed an in vitro methodology to test the antimicrobial effects of a wide range of plant derived substances. Concerning the in vitro method, our objective was to develop a very simple but realistic method able to obtain significant results, using crude intestinal content obtained from the pigs and incubating it for short periods. Productive performance The performance results were very variable among the experiments. These variations were probably due to the use of different facilities, age and health status of the animals and the different composition of the basal diets. Physiologic and physical parameters Ileal and whole tract digestibility and pH measurements in different parts of the gastrointestinal tract were systematically studied in the three in vivo trials but no consistent effects of including plant extracts were found. However, plant extracts inclusion in the diet in the second trial resulted in a decrease of gastric emptying rate and an increase of pH. Microbial populations The most consistent result in the three experiments was an increase in lactobacilli counts with the inclusion of XT in the diets. However, the relevance of this higher intestinal lactobacilli content is not clear, since there was no direct relation with productive benefits. XT inclusion also had an effect on other microbial parameters: purine bases concentration and VFA profile. However, those results were not very consistent and often were highly controversial. Epithelial parameters The effects of XT on the epithelial structure were studied and, once more, the results were very variable depending on the trial. However, a high influence of XT was found on some immune parameters measured in the epithelium and in the lamina propia, results that encourage continuing investigating these effects with more specific techniques. In vitro studies The in vitro method was successfully used to compare different additives. Variations in in vitro fermentation were found not only depending on the additive used but on the age of the animal and on the gastrointestinal tract part used as source of the inoculum. These variations should be studied in more detail in the future. From these studies, we can conclude that the recommended commercial dose of XT presents no direct antimicrobial effect on the studied populations (lactobacilli and enterobacteria). Doses of near to 10000 ppm are needed to obtain antimicrobial effects in jejunum content. However, lower doses were needed when the pure substances instead of the XT mixture were used. These doses were between 500 and 3000 ppm for carvacrol and cinnamaldehyde, depending on the gastrointestinal tract part studied. The minimum dose of all studied substances to produce antimicrobial effects was always lower for the jejunum than for stomach or cecum content.