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No. of bitstreams: 1 renesto_dm_me_jabo.pdf: 787537 bytes, checksum: ea8fc7990e772219cd140ba3099a83a5 (MD5) Previous issue date: 2017-02-23 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O presente trabalho avaliou o efeito da substituição da virginiamicina (VM) por óleos funcionais (OF) a base de mamona e castanha de caju, na recria (Exp. 1) de tourinhos da raça Nelore mantidos em pastagens de Brachiaria brizantha cv Marandu no período de seca de Junho a Setembro de 2015 e terminação (Exp. 2) em confinamento de Outubro a Dezembro do mesmo ano, sendo que nesta fase o tratamento com VM teve inclusão de monensina sódica (MN). Foram utilizados 40 tourinhos Nelore com peso corporal (PC) inicial médio de 403,8 ± 24 kg. Durante o período de seca foram estudados dois níveis de suplementação x dois aditivos, sendo os tratamentos: suplemento proteico/energético com VM (175 ou 70 mg/kg de suplemento) ou OF (2260 ou 810 mg/kg de suplemento), fornecidos na quantidade de 3 ou 6 g por kg-1 do PC, respectivamente. Foram utilizados oito piquetes com capim Marandu (dois por tratamento) manejados em sistema de lotação contínua com duração de 104 dias. Os tratamentos foram arranjados em delineamento inteiramente casualizado em arranjo fatorial 2 × 2 (doses × aditivos) com medidas repetidas no tempo (três períodos). Na fase de recria foram realizadas avaliações de massa, estrutura e qualidade da forragem e desempenho animal. Durante a fase final em confinamento os animais foram alocados em baias individuais recebendo os mesmos aditivos da fase anterior (VM ou OF nas doses de 29,2 e 700 mg/kg de MS de suplemento, respectivamente) sendo mantido o histórico da suplementação utilizado na fase de recria em pastagem, exceto com inclusão de MN (31,7 mg/kg de MS do concentrado) no tratamento VM na fase de confinamento. Foi avaliada a influência do manejo adotado na recria, sobre o consumo e desempenho dos animais na fase de confinamento. Os animais permaneceram no confinamento por 74 dias, quando foram abatidos com peso médio de 582,48 ± 29 kg. Foi adotado delineamento inteiramente casualizado, com quatro tratamentos, com 10 repetições (animais) por tratamento. Na fase de recria, não foram constatadas diferenças nas características da forragem estudadas. O consumo de forragem e de proteína bruta não apresentou diferença nos animais do tratamento 6 g kg-1 do PC, com relação aos tratamentos de menor nível de suplementação. O consumo de matéria seca total, fibra em detergente neutro e de nutrientes digestíveis totais não apresentou diferença, considerando os animais dos diferentes tratamentos. Os resultados referentes aos parâmetros metabólicos, pH e N-NH3 não diferiram entre os tratamentos estudados. A eficiência microbiana não apresentou diferença entre os tratamentos e o balanço de nitrogênio foi maior nos animais dos tratamentos que receberam maior nível de suplementação. O maior nível de suplementação de 6 g kg-1 do PC proporcionou maior taxa de lotação e maior ganho médio diário (GMD), bem como o aditivo VM proporcionou maior desempenho animal. Na fase de terminação em confinamento, os tratamentos com aditivo VM + MN, proporcionaram menor consumo de matéria seca. A suplementação na fase de recria de 3 g kg-1 PC contendo o aditivo OF, apresentou menor rendimento de carcaça após a fase de confinamento. O GMD e a conversão alimentar dos animais não apresentoram diferença dentre os tratamentos na fase de confinamento. / The present project aimed to evaluate the effect of virginiamycin substitution by functional oils, based on castor bean and cashew nut, in the rearing phase (Exp. 1) of Nelore bulls kept in pastures of Brachiaria brizantha cv Marandu in transition period of rainy/dry season from June to September 2015, terminating phase (Exp. 2) in confinement from October to December of the same year, which in this stage, virginiamycin treatment included sodium monensin. 40 Nelore bulls were used, with body weight average of 403,8 ± 24 kg. During transition period were studied two levels of supplementation versus two additives, which were: protein / energetic supplement with virginiamycin (175 or 70 mg/kg of supplement) or functional oils (2260 or 810 mg/kg of supplement), supplied in 3 or 6 g.kg-1 of body weight amount, respectively. Eight areas with Marandu grass (two per treatment) were used in continuous stocking system during 104 days. The treatments were arranged in a completely randomized design in a 2 × 2 factorial arrangement (doses × additives) with repeated measures of time (three periods). At rearing phase were performed evaluations of mass, structure and quality of the forage and animal performance. During the final confinement phase, the animals were allocated to individual stalls receiving the same additives from the previous phase (virginiamycin or functional oils at the doses of 29.2 and 700 mg/kg of dry matter supplement, respectively), maintaining the history of the supplementation used in rearing phase, except the inclusion of sodium monensin (31.7 mg/kg of dry matter supplement) in the virginiamycin treatment at confinement phase. It was evaluated the influence of the management adopted in the rearing, on the consumption and performance of the animals at confinement phase. The animals remained in the confinement for 74 days, when they were slaughtered with average weight about 582.48 ± 29 kg. A completely randomized design was adopted, with four treatments, with 10 replicates (animals) per treatment. In the rearing phase, no differences were observed in the forage characteristics studied. Forage and raw protein consumption did not differ on animals of 6 g.kg-1 of body weight treatment, related with treatments of lower level supplementation. The total dry matter consumption, fiber in neutral detergent and total digestible nutrients did not differ, considering the animals of different treatments. The results regarding the metabolic parameters, pH and N-NH3 did not differ among the treatments studied. The microbial efficiency did not show any difference between the treatments, and the nitrogen balance was higher in the animals whose received highest levels of supplementation. Higher supplementation levels of 6 g.kg-1 of body weight provided higher stocking rate and higher average daily gain, as well as virginiamycin additive provided higher animal performance. On terminating phase in confinement, the treatments with virginiamycin + sodium monensin, provided lower consumption of dry matter. The supplementation on rearing phase of 3 g.kg-1 of body weight, containing functional oils additive, presented lower carcass yield after the confinement phase. Average daily gain and feed conversion of animals showed no difference among the treatments on confinement phase.

Zum Studium des prophylaktischen Einflusses ausgewählter antibiotischer Leistungsförderer [Avilamycin (10 ppm), Avoparcin (15 ppm), Virginiamycin (20 ppm)] und ionophorer Antikokzidia [Monensin (100 ppm), Narasin (70 ppm)] sowie des metaphylaktischen bzw. therapeutischen Einsatzes von Tylosin [Tylan 0,5 g/l H2O] auf das Auftreten und die Ausprägung der Clostridium (Cl.) perfringens-Enterotoxämie (CPE) wurden Untersuchungen an insgesamt 33 Versuchsgruppen mit 825 Broilerküken durchgeführt. Die Erkrankung konnte mittels intraduodenaler Inokulation einer Vollkultur Cl. perfringens Typ A (ATCC 3624) sicher reproduziert werden. Die Morbiditätsrate betrug in allen infizierten Gruppen 100 %. An klinischer Symptomatik zeigte sich hauptsächlich profuser wässriger Durchfall. Schwerere Störungen, Apathie und Anorexie, waren selten und in allen beobachteten Fällen vom schnellen Tod des betreffenden Tieres begleitet. Allgemein fiel auf, daß die infizierten und nicht medikamentierten Tiere schneller und länger erkrankten. Bei infizierten und unmedikamentierten Tieren ergab sich eine Mortalitätsrate von 16 bis 36 %, in den medikamentierten Gruppen maximal 8 %. Tylosin zeigte eine sehr gute metaphylaktischen bzw. therapeutische Wirkung. Die Lebendmasseentwicklung betrachtend, konnte Avoparcin unter den Leistungsförderern beste Ergebnisse erzielen. Ähnliche Resultate wurden in den Kombinationsgruppen [Avilamycin plus Monensin oder Narasin] bzw. mittels Narasin erreicht. In absteigender Reihenfolge zeigten Avilamycin, Virginiamycin und Monensin eine geringere leistungsfördernde Wirkung. Die Bestimmung fäkaler bzw. ileozäkaler Clostridienkonzentrationen lebender, respektive verendeter Hühner erbrachte nur wenige und relativ unbedeutende statistisch gesicherte Korrelationen zu anderen Ergebnissen. Es konnten keine Zusammenhänge zwischen Erregerzahl und Lebendmassezunahme, bzw. Todesursache, aufgedeckt werden. Die Resultate aus allen Versuchen zusammenfassend, müssen den Kombinationen von Avilamycin mit Narasin bzw. Monensin beste Effekte hinsichtlich einer positiven Beeinflussung CPE-bedingter Morbidität, Mortalität und Lebendmasseverluste bescheinigt werden. Tylosin war in der Lage, die Verlustzahlen durch CPE rasch zu senken. Für die Ausprägung kompensatorischer Effekte hinsichtlich der Lebendmasseverluste unter der Infektion muß mit einer größeren Zeitspanne gerechnet werden. Die Polyether und auch Avilamycin sind als Futtermittelzusatzstoffe für die europäische Geflügelhaltung zugelassen. Durch die ständige Kokzidiosebedrohung in den Hühnerbeständen kann auf einen prophylaktischen Einsatz antikokzidieller Futtermittelzusatzstoffe momentan nicht verzichtet werden. Es ist zu vermuten, daß es durch den simultanen Einsatz von Polyether und Leistungsförderer zu einer positiven Beeinflussung der schädigenden Wechselwirkungen von Kokzidien und Cl. perfringens im Darm kommt. Bei vorhandener Empfindlichkeit der Eimerien sollte dies sowohl die Bekämpfung von CPE als auch von Kokzidiosen begünstigen. Der positive Eindruck von Avoparcin spielt, bedingt durch das europaweite Verbot, momentan für die Praxis keine Rolle. Die Entwicklungstendenzen auf dem Sektor antibiotisch wirksamer Futtermittelzusatzstoffe, eng verknüpft mit der bakteriellen Resistenzproblematik, werden in der Arbeit ausführlich diskutiert. / Investigations with 825 chickens in 33 trials were performed in order to find out the prophylactic effect of selected antibiotic growth promoters [avilamycin (10 ppm), avoparcin (15 ppm) virginiamycin (20 ppm)] and polyether ionophore antibiotics [monensin (100 ppm), narasin (70 ppm)] on the incidence of Clostridium (Cl.) perfringens enterotoxemia (CPE) in chickens as well as the therapeutic resp. metaphylactic influence of tylosin [Tylan 0,5 g/l H20]. The enterotoxemia could be reproduced regularly by intraduodenal infection with high numbers of vegetative cells of Cl. perfringens type A (ATCC 3624). The morbidity rate always reached 100 %. In spite of a profuse and watery diarrhoea the chickens normally showed no further considerable disturbances of the general status. Apathy or anorexia were rather rare and immediately followed by Exitus letalis of the related chickens. It was striking that the infected and non-medicated broilers contracted the disease more quickly and for a longer time. The mortality rate among the infected and non-medicated animals was 16 to 36 %, among the medicated groups max. 8 %. Tylosin showed a considerable metaphylactic effect in decreasing CPE mortality. The avoparcin group showed the best weight gain among the growth promoters, comparable to the results by means of the combinations [avilamycin + monensin or narasin] or narasin only. Decreasingly avilamycin, virginiamycin and monensin were less successful. Analysing the faecal resp. ileocecal quantities of Cl. perfringens adduced only a few statistically guaranteed correlation with other results. There was no causal connection between numbers of Cl. perfringens and life weight development. It was impossible to discover a numerical threshold of germs responsible for the death of the chickens. Summarising all the results of the entire attempts the combinations of avilamycin and narasin resp. monensin were the most effective concerning the reduction of morbidity, mortality and life weight losses by CPE. By application of tylosin it was possible to stop the mortality rate quickly. But it needs more time to achieve reductions of the CPE related weight losses. The two polyethers and also avilamycin are still admitted in the European Union. Currently an abandonment of anticoccidial feed supplements seems to be impossible due to the present danger of coccidiosis in poultry. By means of monensin/narasin plus avilamycin the adverse health effects of interactions of both pathogens should be reduced. Presupposing susceptibility of the coccida this should be a notable contribution to a better controlling and to the prevention of CPE and coccidiosis, too.

Made available in DSpace on 2014-06-11T19:28:23Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-02-28Bitstream added on 2014-06-13T19:57:43Z : No. of bitstreams: 1 moretti_mh_me_jabo.pdf: 820927 bytes, checksum: 9e02dc45b7bc9474b5acb3d859d4d028 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Objetivou-se verificar o efeito da suplementação de baixo consumo, sobre o desempenho de novilhos Nelore mantidos em pastagem de Brachiaria brizantha cv. Marandu. O período experimental foi de julho de 2008 a março de 2009 e foi divido em duas fases, secas e águas. Os tratamentos durante o período da seca constituíramse de um controle, sal com uréia, e suplemento mineral enriquecido, este que era acrescido de proteína verdadeira e aditivos. Já no período das águas avaliou-se um tratamento controle, sal mineral e suplemento mineral enriquecido. O delineamento experimental utilizado foi inteiramente casualizado, em esquema de parcela subdividida. No caso da avaliação conjunta das duas fases o delineamento utilizado foi inteiramente casualizado, em esquema fatorial 2 x 2, sendo os fatores os tipos de suplementação em cada uma das fases. Realizaram-se avaliações de pasto e pesagem dos animais a cada ciclo de avaliação dentro dos períodos estudados. No período da seca foi observada diferença estatística em função dos tratamentos avaliados somente no terceiro ciclo. Os animais que receberam suplementação mineral enriquecida (proteína mais aditivos) ganharam 0,600 kg/dia, contra 0,517 kg/dia daqueles receberam sal com uréia. No primeiro e segundo ciclo os tratamentos não apresentaram diferença significativa em relação ao ganho, 0,307 e 0,113 kg/dia. No período das águas os animais que receberam suplementação mineral enriquecida ganharam mais peso do que os animais que receberam suplementação mineral, 0,800 e 0,696 kg/ dia. Concluiu-se que a suplementação mineral acrescida de proteína e aditivos, permite incrementos no ganho de peso dos animais mantidos em regime de pastejo na ordem de 15% / The objective was to test the effect of low intake supplementation on performance of Nelore steers grazing Brachiaria brizantha cv. Marandu. The experiment was from July 2008 to March 2009 divided into two phases, wet and dry seasons. The treatments during the dry season consisted of a control, a salt urea, and mineral supplement, that it was increased with true protein and additives. In the wet season we evaluate a control treatment, mineral salt and a supplement mineral enriched. The lineation experiment was completely randomized in parcel scheme subdivided. In the case of joint evaluation of the two phases, the lineation was completely randomized in scheme factorial 2X 2, the factors being the type of supplementation in each phase. Evaluations were performed on grazing and animals weighed each evaluation cycle within the periods studied. During the dry season was a statistical difference in the treatments evaluated only in the third cycle. The animals that received mineral supplementation enriched (protein more additive) gained 0.600 kg/day, against 0.517 kg/day those who received salt with urea. In the first and second cycle the treatments showed no significant difference in relation to gain, 0.307 e 0,113 kg/day. In wet season the animals receiving mineral supplementation enriched gained more weight than animals receiving just mineral supplementation, 0.800 e 0.696 kg/day. Concludes the mineral supplementation enriched with protein and additive, allows greater weight gains than animals kept in grazing to order 15%

Orientador: Flávio Dutra de Resende / Banca: Ricardo Andrade Reis / Banca: Marco Antonio Alves Balsalobre / Resumo: Objetivou-se verificar o efeito da suplementação de baixo consumo, sobre o desempenho de novilhos Nelore mantidos em pastagem de Brachiaria brizantha cv. Marandu. O período experimental foi de julho de 2008 a março de 2009 e foi divido em duas fases, secas e águas. Os tratamentos durante o período da seca constituíramse de um controle, sal com uréia, e suplemento mineral enriquecido, este que era acrescido de proteína verdadeira e aditivos. Já no período das águas avaliou-se um tratamento controle, sal mineral e suplemento mineral enriquecido. O delineamento experimental utilizado foi inteiramente casualizado, em esquema de parcela subdividida. No caso da avaliação conjunta das duas fases o delineamento utilizado foi inteiramente casualizado, em esquema fatorial 2 x 2, sendo os fatores os tipos de suplementação em cada uma das fases. Realizaram-se avaliações de pasto e pesagem dos animais a cada ciclo de avaliação dentro dos períodos estudados. No período da seca foi observada diferença estatística em função dos tratamentos avaliados somente no terceiro ciclo. Os animais que receberam suplementação mineral enriquecida (proteína mais aditivos) ganharam 0,600 kg/dia, contra 0,517 kg/dia daqueles receberam sal com uréia. No primeiro e segundo ciclo os tratamentos não apresentaram diferença significativa em relação ao ganho, 0,307 e 0,113 kg/dia. No período das águas os animais que receberam suplementação mineral enriquecida ganharam mais peso do que os animais que receberam suplementação mineral, 0,800 e 0,696 kg/ dia. Concluiu-se que a suplementação mineral acrescida de proteína e aditivos, permite incrementos no ganho de peso dos animais mantidos em regime de pastejo na ordem de 15% / Abstract: The objective was to test the effect of low intake supplementation on performance of Nelore steers grazing Brachiaria brizantha cv. Marandu. The experiment was from July 2008 to March 2009 divided into two phases, wet and dry seasons. The treatments during the dry season consisted of a control, a salt urea, and mineral supplement, that it was increased with true protein and additives. In the wet season we evaluate a control treatment, mineral salt and a supplement mineral enriched. The lineation experiment was completely randomized in parcel scheme subdivided. In the case of joint evaluation of the two phases, the lineation was completely randomized in scheme factorial 2X 2, the factors being the type of supplementation in each phase. Evaluations were performed on grazing and animals weighed each evaluation cycle within the periods studied. During the dry season was a statistical difference in the treatments evaluated only in the third cycle. The animals that received mineral supplementation enriched (protein more additive) gained 0.600 kg/day, against 0.517 kg/day those who received salt with urea. In the first and second cycle the treatments showed no significant difference in relation to gain, 0.307 e 0,113 kg/day. In wet season the animals receiving mineral supplementation enriched gained more weight than animals receiving just mineral supplementation, 0.800 e 0.696 kg/day. Concludes the mineral supplementation enriched with protein and additive, allows greater weight gains than animals kept in grazing to order 15% / Mestre

Nott Katherine (2007). Synthèse de dérivés tensioactifs de virginiamycine et étude de leurs propriétés (Thèse de doctorat). Gembloux, Académie universitaire Wallonie-Europe, Faculté Universitaire des Sciences Agronomiques, 317 p., 66 tabl., 79 fig. Résumé : Suite à la purification du facteur M1 de la virginiamycine, des dérivés ont été synthétisés et purifiés. Deux types de mono-dérivés ont été obtenus : des esters avec des acides gras (modification de M1 au niveau de lhydroxyle en C-14) et des oximes (liaison chimiosélective) dérivées dacides aminés (réaction avec le carbonyle cétonique en C-16). Des di-dérivés ont également été produits en modifiant simultanément ces deux sites réactionnels avec un acide gras dune part et un aminooxy acétyle acide aminé dautre part. Lidentité des dérivés a été confirmée par un ensemble de techniques spectrales (infrarouge, masse et résonance magnétique nucléaire). Leurs propriétés tensioactives fondamentales ont été étudiées et un criblage de leurs activités antimicrobiennes a été réalisé. Laugmentation simultanée des caractères hydrophobe et hydrophile de M1 (cas des di-dérivés) est nécessaire pour lui conférer un caractère tensioactif marqué. Les di-dérivés présentent des caractéristiques tensioactives (cinétique dadsorption et formation de micelles) similaires voire supérieures à celles dautres tensioactifs classiques de la littérature et de certains biosurfactants tels que les lipopeptides de Bacillus subtilis. La synthèse de di-dérivés a augmenté la capacité de M1 à pénétrer dans un modèle membranaire. Le rôle favorable de M1 sur certaines propriétés de surface a été mis en évidence par comparaison des propriétés des di-dérivés avec celles de molécules témoins de type amide formées entre un acide gras et un acide aminé. La gamme de di-dérivés synthétisés a permis de contribuer aux études des relations structure fonction dans le domaine des tensioactifs. Le criblage des activités antibactériennes des dérivés a montré limportance des fonctions hydroxyle et cétone pour lactivité antibiotique initiale de M1. Les di-dérivés ainsi que les molécules témoins synthétisées présentent une activité vis-à-vis de certaines bactéries et moisissures. Cela pourrait être attribué à la capacité de ces molécules à déstabiliser les membranes de ces microorganismes. Nott Katherine (2007). Synthesis of surface active derivatives of virginiamycin and study of their properties (PhD thesis in french). Gembloux, Belgium, University Academy Walloon Region-Europe, Gembloux Agricultural University, 317 p., 66 tabl., 79 fig. Summary : Following the purification of the M1 factor of virginiamycin, derivatives have been synthesised and purified. Two types of mono-derivatives have been obtained : esters with fatty acids (modification of M1 at its C-14 hydroxyl) and oximes (chemoselective ligation) with aminooxylated amino acids (reaction with the ketone carbonyl at C-16). Bis-derivatives have also been produced by simultaneously modifying the two reactive sites with a fatty acid on one side and an aminooxylated amino acid on the other. The identity of each derivative has been confirmed by a combination of spectral techniques (infrared, mass and nuclear magnetic resonance). Their fundamental tensioactive properties have been studied and screening of their activity against microorganisms has been undertaken. The simultaneous increase of M1s hydrophobic and hydrophilic character (the case of the bis-derivatives) was necessary to render M1 surface active. The bis-derivatives have surface active characteristics (adsorption kinetics and micelle formation) similar or even superior to those of classical surfactants of the literature and of some biosurfactants such as Bacillus subtiliss lipopeptides. The synthesis of the bis-derivatives has enhanced M1s capacity to penetrate a biological membrane model. M1s positive impact on some surface properties has been shown by comparison with amide type molecules obtained by reacting a fatty acid with an amino acid. The range of the synthesised bis-derivatives has allowed this work to contribute to the studies of the relationships between surfactants structures and their properties. The screening of the derivatives antibacterial activities has shown the importance of the hydroxyl and ketone groups for M1s initial antibiotic activity. The bis-derivatives and the reference molecules show an activity against some bacteria and fungi. This may be due to their capacity to destabilise the microorganisms membranes.

Zum Studium des prophylaktischen Einflusses ausgewählter antibiotischer Leistungsförderer [Avilamycin (10 ppm), Avoparcin (15 ppm), Virginiamycin (20 ppm)] und ionophorer Antikokzidia [Monensin (100 ppm), Narasin (70 ppm)] sowie des metaphylaktischen bzw. therapeutischen Einsatzes von Tylosin [Tylan 0,5 g/l H2O] auf das Auftreten und die Ausprägung der Clostridium (Cl.) perfringens-Enterotoxämie (CPE) wurden Untersuchungen an insgesamt 33 Versuchsgruppen mit 825 Broilerküken durchgeführt. Die Erkrankung konnte mittels intraduodenaler Inokulation einer Vollkultur Cl. perfringens Typ A (ATCC 3624) sicher reproduziert werden. Die Morbiditätsrate betrug in allen infizierten Gruppen 100 %. An klinischer Symptomatik zeigte sich hauptsächlich profuser wässriger Durchfall. Schwerere Störungen, Apathie und Anorexie, waren selten und in allen beobachteten Fällen vom schnellen Tod des betreffenden Tieres begleitet. Allgemein fiel auf, daß die infizierten und nicht medikamentierten Tiere schneller und länger erkrankten. Bei infizierten und unmedikamentierten Tieren ergab sich eine Mortalitätsrate von 16 bis 36 %, in den medikamentierten Gruppen maximal 8 %. Tylosin zeigte eine sehr gute metaphylaktischen bzw. therapeutische Wirkung. Die Lebendmasseentwicklung betrachtend, konnte Avoparcin unter den Leistungsförderern beste Ergebnisse erzielen. Ähnliche Resultate wurden in den Kombinationsgruppen [Avilamycin plus Monensin oder Narasin] bzw. mittels Narasin erreicht. In absteigender Reihenfolge zeigten Avilamycin, Virginiamycin und Monensin eine geringere leistungsfördernde Wirkung. Die Bestimmung fäkaler bzw. ileozäkaler Clostridienkonzentrationen lebender, respektive verendeter Hühner erbrachte nur wenige und relativ unbedeutende statistisch gesicherte Korrelationen zu anderen Ergebnissen. Es konnten keine Zusammenhänge zwischen Erregerzahl und Lebendmassezunahme, bzw. Todesursache, aufgedeckt werden. Die Resultate aus allen Versuchen zusammenfassend, müssen den Kombinationen von Avilamycin mit Narasin bzw. Monensin beste Effekte hinsichtlich einer positiven Beeinflussung CPE-bedingter Morbidität, Mortalität und Lebendmasseverluste bescheinigt werden. Tylosin war in der Lage, die Verlustzahlen durch CPE rasch zu senken. Für die Ausprägung kompensatorischer Effekte hinsichtlich der Lebendmasseverluste unter der Infektion muß mit einer größeren Zeitspanne gerechnet werden. Die Polyether und auch Avilamycin sind als Futtermittelzusatzstoffe für die europäische Geflügelhaltung zugelassen. Durch die ständige Kokzidiosebedrohung in den Hühnerbeständen kann auf einen prophylaktischen Einsatz antikokzidieller Futtermittelzusatzstoffe momentan nicht verzichtet werden. Es ist zu vermuten, daß es durch den simultanen Einsatz von Polyether und Leistungsförderer zu einer positiven Beeinflussung der schädigenden Wechselwirkungen von Kokzidien und Cl. perfringens im Darm kommt. Bei vorhandener Empfindlichkeit der Eimerien sollte dies sowohl die Bekämpfung von CPE als auch von Kokzidiosen begünstigen. Der positive Eindruck von Avoparcin spielt, bedingt durch das europaweite Verbot, momentan für die Praxis keine Rolle. Die Entwicklungstendenzen auf dem Sektor antibiotisch wirksamer Futtermittelzusatzstoffe, eng verknüpft mit der bakteriellen Resistenzproblematik, werden in der Arbeit ausführlich diskutiert. / Investigations with 825 chickens in 33 trials were performed in order to find out the prophylactic effect of selected antibiotic growth promoters [avilamycin (10 ppm), avoparcin (15 ppm) virginiamycin (20 ppm)] and polyether ionophore antibiotics [monensin (100 ppm), narasin (70 ppm)] on the incidence of Clostridium (Cl.) perfringens enterotoxemia (CPE) in chickens as well as the therapeutic resp. metaphylactic influence of tylosin [Tylan 0,5 g/l H20]. The enterotoxemia could be reproduced regularly by intraduodenal infection with high numbers of vegetative cells of Cl. perfringens type A (ATCC 3624). The morbidity rate always reached 100 %. In spite of a profuse and watery diarrhoea the chickens normally showed no further considerable disturbances of the general status. Apathy or anorexia were rather rare and immediately followed by Exitus letalis of the related chickens. It was striking that the infected and non-medicated broilers contracted the disease more quickly and for a longer time. The mortality rate among the infected and non-medicated animals was 16 to 36 %, among the medicated groups max. 8 %. Tylosin showed a considerable metaphylactic effect in decreasing CPE mortality. The avoparcin group showed the best weight gain among the growth promoters, comparable to the results by means of the combinations [avilamycin + monensin or narasin] or narasin only. Decreasingly avilamycin, virginiamycin and monensin were less successful. Analysing the faecal resp. ileocecal quantities of Cl. perfringens adduced only a few statistically guaranteed correlation with other results. There was no causal connection between numbers of Cl. perfringens and life weight development. It was impossible to discover a numerical threshold of germs responsible for the death of the chickens. Summarising all the results of the entire attempts the combinations of avilamycin and narasin resp. monensin were the most effective concerning the reduction of morbidity, mortality and life weight losses by CPE. By application of tylosin it was possible to stop the mortality rate quickly. But it needs more time to achieve reductions of the CPE related weight losses. The two polyethers and also avilamycin are still admitted in the European Union. Currently an abandonment of anticoccidial feed supplements seems to be impossible due to the present danger of coccidiosis in poultry. By means of monensin/narasin plus avilamycin the adverse health effects of interactions of both pathogens should be reduced. Presupposing susceptibility of the coccida this should be a notable contribution to a better controlling and to the prevention of CPE and coccidiosis, too.