Epizootic rabbit enteropathy. Study of early phenomena with fresh inoculum and attempt at inactivation

[EN] Using 180 35-day-old SPF rabbits, this study used the effectiveness of bacitracin as a tool for acquiring more information on the various phases of ERE, in particular during the hours inoculation. Five groups of animals were used, including 3 treatments with Bacivet S(R) (bacitracin) at different times from inoculation, with the standard inoculum TEC3. Three parameters were studied: growth, mortality and stomach noises (borborygmi). A significant fall in growth rate was observed during the first 18 hours following the inoculation in all the inoculated groups, both medicated and not medicated. Treatment with bacitracin eliminated mortality and borborygmi, but not the initial fall in growth rate. Treatment starting 18 hours after inoculation is less effective during the acute phase than the preventive treatment. With a preventive treatment interrupted as soon as 18 hours after inoculation, a delay of several days was observed before the appearance of the disease (fall in growth rate, manifestation of borborygmi) and total mortality was reduced. Very few pathogens can explain this early fall in growth rate. Bacitracin is an antibiotic which offers good control of the disease, and probably of the pathogen but not of the physio-pathological disturbances in the first few hours. The intervention of an exogenic toxin in the first hours of contamination seems likely. Borborygmi are important criteria. The intensity and/or frequency could be used as semi-quantitative criteria to characterize the disease and for the prognosis. In a simultaneous trial, a group was contaminated with the same inoculum, heated for 10 min at 55°C, in order to obtain more information on the type of pathogen involved in the etiology of ERE. This treatment did not modify the virulence of the inoculum.This research received financial help from the Ministry for Agriculture of France (DGAL - ITAVI).Coudert, P.; Licois, D. (2005). Epizootic rabbit enteropathy. Study of early phenomena with fresh inoculum and attempt at inactivation. World Rabbit Science. 13. doi:10.4995/wrs.2005.515SWORD1

Characterization of Clostridium perfringens presence and concentration of its [alfa]-toxin in the caecal contents of fattening rabbits suffering from digestive diseases

[EN] Digestive diseases are the main cause of morbidity and mortality in growing rabbits. Clostridium perfringens is a widely occurring pathogenic bacterium in enteric diseases of domestic animals and its pathogenicity stems from the production of potent exotoxins. This work aimed to quantify the concentration of C. perfringens [alfa]-toxin in caecal samples of rabbits with digestive diseases and relate these concentrations to C. perfringens counts. Additionally, C. perfringens strains isolated from rabbits with clinical lesions of Epizootic Rabbit Enteropathy (ERE) were toxinotyped. To conduct this work, a total of 711 rabbits weaned at 35 days were housed in pairs and fattened until the age of 63 days. No experimental infection was performed and no antibiotics were provided in the feed or drinking water. All rabbits displaying symptoms of digestive diseases were slaughtered and necropsied. At 46 days, 88 healthy rabbits were also slaughtered. Caecal contents were sampled from all slaughtered animals. Thirty-seven out of the 69 rabbits with digestive diseases (88.5% of sick animals) showed ERE-confirmed symptoms and lesions. Apart from diarrhoea, the most constant ERE signs were abdominal bloating and borborygmi. At necropsy, the anterior digestive tract was found filled with large amounts of gas and liquid. Twenty-seven rabbits had liquid caecal contents whereas caecal impaction only appeared in 10 rabbits. Live weight was lower by 49.2% (P<0.001) in diseased rabbits as compared with healthy rabbits of the same age. For C. perfringens counts lower than 6.0 log cfu/g, the [alfa]-toxin concentration remained below 2.6 [micro]g/mg. However, for bacterial counts above 6.0 log cfu/g the concentration of [alfa]-toxin ranged from 0.12 to 60.9 [micro]g/mg. Nevertheless, both caecal concentration of C. perfringens (7.65 vs. 3.09 log cfu/g, P<0.001) and that of its [alfa]-toxin (6.02 vs. 0.17 [micro]g/mg, P<0.001) were higher in diseased rabbits than in healthy ones. C. perfringens toxinotype A was found in all ERE-affected rabbits. No other toxinotype was identified and no isolate contained the enterotoxin gene. In conclusion, C. perfringens [alfa]-toxin should not be considered a good indicator of the bacterium's presence, as high counts of colonies are not always associated with high toxin concentrations.The first author sincerely thanks the Universidad Politécnica de Madrid for funding his stay at Dr. Ducatelle’s laboratory in Universiteit Gent where he was trained in culture-based microbiology and toxin analyses. This work was supported by CICYT project AGL2008-00627.Romero, C.; Nicodemus, N.; Jarava, ML.; Menoyo, D.; Blas, CD. (2011). Characterization of Clostridium perfringens presence and concentration of its [alfa]-toxin in the caecal contents of fattening rabbits suffering from digestive diseases. World Rabbit Science. 19(4):177-189. https://doi.org/10.4995/wrs.2011.941SWORD17718919

Impacts socio-économiques sur les cuniculteurs de la vaccination des lapins contre les coccidioses intestinales au Bénin

Les coccidioses constituent l’une des maladies les plus meurtrières chez les lapins. Pour mieux contrôler cette affection, une prophylaxie vaccinale est mise au point. La réussite d’une telle innovation passe par la perception des cuniculteurs. Ainsi, la présente étude a été entreprise afin de déterminer les facteurs favorisant l’adoption par les éleveurs de la vaccination des lapins contre les coccidioses. Les enquêtes menées auprès des cuniculteurs ont révélé que 100% d’entre eux ont une opinion favorable du vaccin. De même, 83,3% des éleveurs ont affirmé que le vaccin était efficace. Par ailleurs, 80% des éleveurs ont déclaré connaître la coccidiose. Parmi ceux-ci, 62,5% avait bien décrit les signes cliniques de la coccidiose. L’étude économique a montré que la vaccination engendre un bénéfice net de 123,2 F CFA par lapin comparativement aux lapins non vaccinés. La vaccination s’avère efficace et est bien appréciée par les utilisateurs. Son adoption contribuera à améliorer les conditions de vie des cuniculteurs.© 2015 International Formulae Group. All rights reserved.Mots clés: Oryctolagus cuniculus, cuniculture, coccidies, prophylaxie, immunisation, adoptionEnglish Title:  Socio-economic effects on the rabbit breeders of rabbit’s vaccination against intestinal coccidiosis in BeninEnglish AbstractCoccidiosis is recognized as being one of the major serious diseases in rabbit breeding. For a better control of this disease, a vaccination program is set up. The perception of the rabbit breeders determines the success of this innovation. Thus, this study was undertaken in order to determine the factors which favour the adoption of the rabbit vaccination against coccidiosis by the rabbit breeders. Survey performed on rabbit  breeding revealed that 100% of the breeders included in the survey thought that vaccine is useful for the control of coccidiosis. An average of 83.3% of breeders has reported that the use of vaccine was effective to control coccidiosis. Likewise among rabbit breeders included in the study, an average of 80% has been reported to know coccidiosis. Among those breeders, an average of 62.6% was reported to know well clinical symptoms of coccidiosis. Economical study carried out on rabbit breeding showed that vaccine involves a net profit of 132.2 F CFA per vaccinated rabbit compared to non vaccinated rabbits. Vaccine turns out to an effective control of coccidiosis in rabbit and was well appreciated by the breeders. Its adoption will help improving rabbit breeders’ life.© 2015 International Formulae Group. All rights reserved.Keywords: Oryctolagus cuniculus, rabbit breeding, coccidia, prevention, immunization, adoptio

Pyrosequencing study of caecal bacterial community of rabbit does and kits from a farm affected by epizootic rabbit enteropathy

[EN] Epizootic Rabbit Enteropathy (ERE) is a disease of unknown aetiology that mainly affects post-weaning animals. Caecotrophs from animals in a farm affected by ERE were analysed to identify changes in the microbiological profile of growing rabbits. Does and kits at weaning (28 d) and the same rabbits ten days later (38 d) were used for a comparison using Roche 454 pyrosequencing of hypervariable V3-V5 regions of the 16S rRNA genes. The caecal bacterial community was dominated by the Firmicutes phylum (about 80%), followed by Bacteroidetes (15%), although relative abundances changed according to animal age (among does and kits at 28 and 38 d) and health status (affected or not by ERE). Two dominant families were classified within the Firmicutes phylum: Ruminococcaceae and Lachnospiraceae (50 and 20% of the sequences, respectively). In kits affected by ERE, relative abundance of Ruminococcus and Bacteroides genera decreased and increased, respectively, compared to healthy kits at the same age (28 and 38 d). The principal coordinate analysis plot revealed that kits at 28 d of age cluster together and apart from the does and the healthy 38-d rabbit groups. When only growing rabbits are considered, kits that showed symptoms of ERE clustered separately. Results suggest a different caecal bacterial community of rabbits affected by ERE. These findings highlight the need to identify different stages of the disease.This work was supported by Project AGL 2006-07596  (Ministry of Education and Science, Spain), with participation of the Department of Industry and Innovation of the Government of Aragon and the European Social Fund. The stage of N. Rodríguez-Romero in the University of Zaragoza was financed by a Doctoral fellowship from the Universidad Nacional Experimental del Táchira (San Cristóbal, Venezuela).Abecia, L.; Rodríguez-Romero, N.; Martínez-Fernández, G.; Martínez Vallespín, B.; Fondevila, M. (2017). Pyrosequencing study of caecal bacterial community of rabbit does and kits from a farm affected by epizootic rabbit enteropathy. World Rabbit Science. 25(3):261-272. https://doi.org/10.4995/wrs.2017.5230SWORD26127225

Inoculation and bacterial analyses of fractions obtained from the reference inoculum TEC4 which experimentally reproduces epizootic rabbit enteropathy

[EN] The aetiology of epizootic rabbit enteropathy (ERE) is still unknown despite ten years of continuous research. A putative bacterial aetiology is the basis of current research. The fractionation of the reference inoculum (TEC4) is a major step towards finding the potential bacterial agent(s). In this study, TEC4 was fractionated by different techniques: centrifugation on discontinuous sucrose gradient, cell adherence and chloroform/ethanol treatment. The different fractions were inoculated into SPF rabbits and analyzed with classical bacteriological techniques. ERE was reproduced with two of the six fractions obtained. Four species never previously cultured from TEC were identified in the process but, to date, none of them seems to be the aetiology of ERE.This work was supported by a Grant from the «Service Publique Fédéral Santé Publique, sécurité de la chaîne alimentaire et environnement: Division Recherche contractuelle», contract RT 06/7 MINRABBIT. N. Huybens is a PhD fellow of the “Fonds pour la formation à la Recherche dans l’Industrie et dans l’Agriculture” (F.R.I.A.).Huybens, N.; Houeix, J.; Licois, D.; Mainil, J.; Marlier, D. (2009). Inoculation and bacterial analyses of fractions obtained from the reference inoculum TEC4 which experimentally reproduces epizootic rabbit enteropathy. World Rabbit Science. 17(4):185-193. https://doi.org/10.4995/wrs.2009.64318519317

Mathematical Modeling of Transport and Degradation of Feedstuffs in the Small Intestine

We describe a mathematical modeling of the digestion in the small intestine. The main interest of our work is to consider, at the same time, different aspects of the digestion i.e. the transport of the bolus all along the intestine, feedstuffs degradation according to the enzymes and local physical conditions, and nutrients absorption. A system of coupled ordinary differential equations is used to model these phenomena. The major unknowns of this system are the position of the bolus and its composition. This system of equations is solved numerically. We present different numerical computations for the degradation, absorption and transport of the bolus with acceptable accuracy with experimental data. The main feature and interest of this model are its generality. Even if we are at an early stage of development, our approach can be adapted to treat any kind of feedstuffs in any non-ruminant animal to predict the composition and velocity of bolus in the small intestine

Challenging the growing rabbit with a moderately pathogenic E. coli under ad libitum or limited feed intake conditions: impact on digestive physiology, bacterial communities, and on post-weaning growth

[EN] The impact of a challenge with moderately pathogenic Escherichia coli O128:C6 on the digestive physiology and gut bacterial community of growing rabbits under two feeding programmes was analysed. Upon weaning (28 d old), 180 rabbits were allocated to four groups (9 cages of 5 rabbits per group) for two weeks: group C100 was non-inoculated and fed ad libitum; C70 was non-inoculated and feed intake was limited to 70% of C100; I100 and I70 were inoculated and fed ad libitum or restricted to 70%, respectively. At the age of 31 d (D0), rabbits were orally inoculated with E. coli (2.2×108 colony forming units/rabbit). The effects of inoculation spiked on D4, with a 28% lower growth rate for I100 than for C100. Limited feed intake reinforced the inoculation’s effects on growth: I70 had a 66% lower growth rate than C70. The morbidity rate peaked at 42% between D4 and D7 for inoculated groups, without significant effect of the feed intake level. E. coli concentration peaked on D5/D6 in the caecum of the I100 and I70 groups. Inoculation reduced by 30% (P&lt;0.05) the villus height/crypt depth and villus/crypt area ratios in the ileum, with no significant effect of the intake level. Inoculation was associated with a tenfold increase in serum haptoglobin (P&lt;0.001) for both ad libitum and restricted rabbits. On D5, the inoculation modified the structure of the ileal bacterial community (P&lt;0.05), but not that of the caecum. The feed intake level did not affect either the structure or diversity of the bacterial community, both in the ileum and caecum.The authors would like to thank Alain Milon and Stéphane Bertagnoli (ENV Toulouse) who provided the E. coli O128:C6 strain we used. We are also grateful to ANSES staff in the “Service d’Elevage et d’Expérimentation en Pathologie Aviaire” (M. Amelot, L. Le Moal, T. Le Coq, D. Courtois and M. Morvan) and for the technical help of F. Lalande (HQPAP, ANSES) and L. Gordon.Martignon, M.; Burel, C.; Licois, D.; Reperant, E.; Postollec, G.; Valat, C.; Gidenne, TN. (2021). Challenging the growing rabbit with a moderately pathogenic E. coli under ad libitum or limited feed intake conditions: impact on digestive physiology, bacterial communities, and on post-weaning growth. World Rabbit Science. 29(1):1-10. https://doi.org/10.4995/wrs.2021.14089OJS110291Agnoletti F. 2012. Update on rabbit enteric diseases: despite improved diagnostic capacity, where does disease control and prevention stand? In: Proc. 10th World Rabbit Congress, World Rabbit Science Association (WRSA) publ., Sharm El Sheik, Egypt, 1113-1127.Allison S.D., Martiny J.B.H. 2008. Resistance, resilience, and redundancy in microbial communities. Proc. Nat. 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Microb., 27: 743-747. https://doi.org/10.1128/JCM.27.4.743-747.1989Cantey J.R., Inman L.R. 1981. Diarrhea due to Escherichia coli strain RDEC-1 in the rabbit. The Peyer's patch as the initial site of attachement and colonization. J. Infect. Diseases, 143: 440-446. https://doi.org/10.1093/infdis/143.3.440Combes S., Nice F., Licois D., Fortun-Lamothe L., Gidenne T. 2009. Response of digestive bacterial community of rabbits after experimental infection of epizootic enteropathy syndrome (ERE). In: Proc. 13èmes Journées de la Recherche Cunicole (Bolet G., Ed.), ITAVI publ., Paris., France, 227-230.Combes S., Massip K., Martin O., Furbeyre H., Cauquil L., Pascal G., Bouchez O., Le Floc'h N., Zemb O., Oswald I.P., Gidenne T., 2017. Impact of feed restriction and housing hygiene conditions on specific and inflammatory immune response, the cecal bacterial community and the survival of young rabbits. 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Evolution of the peripheral blood lymphocyte populations in multiparous rabbit does with two reproductive management rhythms

The emergence of epizootic rabbit enteropathy is leading to changes in weaning protocols in commercial rabbitries. Traditional weaning protocols are being replaced with late weaning, beyond 35 days postpartum (dpp). The main objectives of this study were to compare the peripheral blood lymphocyte populations of multiparous rabbit does under two reproductive rhythms (insemination at 11 dpp and weaning at 28 dpp, insemination at 25 dpp and weaning at 42 dpp), and to assess the influence on those of kits. Samples of peripheral blood were taken in 22 adult females and 44 of their kits at different critical times, and several lymphocytic populations were evaluated by flow cytometry. Additionally, the perirenal fat thickness of does was also measured at partum and weaning to observe if body condition correlates with lymphocyte populations. During whole lactation, counts of total, CD5 +, CD4 + and CD8 + lymphocytes of females were generally lower with weaning at 42 dpp compared to 28 dpp. Moreover, counts of total, B and CD5 + lymphocytes in rabbit does weaned at 42 dpp correlated to their body condition (+0.60 to 0.82; P<0.05), contrary to that observed in rabbit does weaned at 28 dpp. Some correlations between lymphocyte counts in both groups of does and weaning rabbits were observed. At weaning, those young rabbits weaned at 42 dpp had a significantly lower number of CD4 + lymphocytes than those weaned at 28 dpp (P<0.01). In conclusion, the 42 ddp rabbit does presented a lower number of total lymphocytes and lymphocytic subpopulations during lactation and at weaning, as well as lesser capacity of adjustment during the gestation-lactation cycle. © 2010 Elsevier B.V.This study has been supported by grants from the CEU-Cardenal Herrera University (Banco Santander/CEU-UCH: Copernicus Program (PRCEU-UCH/COOP 01/08), Generalitat Valenciana (ACOMP/2009/207 and ACOMP/2010/062) and the Comision Interministerial de Ciencia y Tecnologia (AGL2008-00273/GAN). Grants for Selena Ferrian and Irene Guerrero from Generalitat Valenciana (the Santiago Grisolia programme) and from the CEU-Cardenal Herrera University, respectively, are gratefully acknowledged.Guerrero, I.; Ferrian, S.; Blas Ferrer, E.; Pascual Amorós, JJ.; Cano, JL.; Corpa, JM. (2011). Evolution of the peripheral blood lymphocyte populations in multiparous rabbit does with two reproductive management rhythms. Veterinary Immunology and Immunopathology. 140(1-2):75-81. https://doi.org/10.1016/j.vetimm.2010.11.017S75811401-