This thesis was to determine the prevalence and distribution of paratuberculosis in the Ontario dairy sheep and dairy goat industries, identify potential risk factors for herds which tested positive, evaluate the accuracy of seven commercially available individual and two bulk tank diagnostic tests in these two populations, and determine the circulating strains of Mycobacterium avium ssp. paratuberculosis in faecal isolates obtained. A cross-sectional study was conducted between October 2010 and August 2011 in 29 goat herds and 21 sheep flocks located in Ontario. On each farm, 20 lactating animals over the age of two years were randomly selected and faeces, blood, and milk were sampled from each animal, and a bulk milk sample from each herd. A questionnaire inquiring about herd management and biosecurity behaviours was also completed. The seven individual animal tests evaluated were: faecal culture using the BACTEC® MGIT™ 960 liquid culture system, direct faecal PCR (Tetracore®, Rockville, MD) based on the hspX gene, the Prionics® ELISA on serum and milk, the IDEXX® ELISA on serum and milk, and the agar gel immunodiffusion (AGID) test on serum. The test evaluations used both frequentist (faecal culture - reference test) and Latent Class Analysis/Bayesian (LCA/BM) methods (no reference test). In goat herds, faecal culture demonstrated the highest sensitivity (Se), 81.1% (LCA/BM). In sheep, while faecal culture demonstrated the highest Se, 49.5%, there was a small probability it was higher than faecal PCR Se at 42.4%. The bulk tank tests evaluated were the 'Hyper-ELISA' test and real-time PCR test based on IS900 (AntelBio®). While PCR did not demonstrate sufficiently high Se to be used as a herd-level test, the Hyper-ELISA performed well as a herd-level test identifying farms with high prevalence when the cut-off was reduced to 0.05. Overall herd-level apparent prevalence was 79.3% in goat herds and 57.1% in sheep flocks when faecal culture was the reference standard and true herd-level prevalence (LCA/BM) was 83.0% and 66.8% in each population respectively. This high prevalence reveals a need for the implementation of a small ruminant paratuberculosis control program in Ontario, Canada based on testing, improving youngstock management, and strengthening biosecurity practices. / AHSI, OMAF

Made available in DSpace on 2016-12-08T16:24:19Z (GMT). No. of bitstreams: 1 PGCA14MA154.pdf: 1313169 bytes, checksum: 4095d82961e0759ed84999755c5e444b (MD5) Previous issue date: 2014-11-07 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Ovine toxoplasmosis has important implications by causing reproductive disorders in this species and for being a zoonosis. This study aimed to determine the occurrence of antibodies against Toxoplasma gondii and to detect the agent in the dairy sheep flocks in western of state of Santa Catarina. From March to July 2013, 298 blood samples were collected from dairy sheep on two farms in Chapecó, SC. Samples were processed by IFI (≥1: 64). From the total, 37 (12.4%) were positive for T. gondii with titers of 1:64 (32) and 1: 256 (five). For the animals selection, which were studied looking for the presence of the agent in the milk, 128 blood samples from sheep in lactation period were collected, which were processed by IFI (≥1: 64) of which 42 (32.8%) were positive, with titers 1:64, (26) 1 256 (12), 1: 1024 (three) and 1: 4096 (one). For the detection of parasites in milk, techniques of mouse bioassay were employed (22 milk samples from eight sheep with antibody titers against T. gondii ≥256) and PCR, for the detection of T. gondii in the brains of mice inoculated bioassay and also directly from milk (108 samples from 42 seropositive sheep (≥64) in different lactation periods - 40, 90 and 120 days). SAG2R4 SAG2F4 primers were used. In 42 ewes in lactation period and seropositive for T. gondii it was possible to detect DNA of the parasite in the milk of 30.95% (13/42) of the animals. The isolation was impossible in bioassay, however the agent DNA was detected in mice brains inoculated with milk from eight sheep (a sample of the 45th day of lactation and seven in the collection of 90th day). The parasite DNA was detected directly from the milk in samples of the second collection (90 days of lactation) in five animals. Positive PCR samples were sequenced and the results confirmed ≥97% identity with the membrane antigen P22 gene of T. gondii. The results showed that the occurrence of antibodies against T. gondii in dairy sheep in western of state of Santa Catarina is lower when compared with that observed in steak sheep in the state and that the DNA of T. gondii is present in the milk of sheep, representing a possible source of infection to humans through the consumption of milk "in natura" and / or derivatives, besides the possibility of lactogenic transmission to lambs / A toxoplasmose ovina apresenta implicações sanitárias importantes por causar desordens reprodutivas nesta espécie e por ser uma zoonose. Os objetivos do presente trabalho foram determinar a ocorrência de anticorpos contra Toxoplasma gondii e detectar o agente no leite de rebanhos ovinos leiteiros na região Oeste de Santa Catarina. De março a julho de 2013, foram colhidas 298 amostras de sangue de ovinos leiteiros em duas propriedades em Chapecó, SC. As amostras foram processadas pela RIFI (≥1:64). Do total, 37 (12,4%) foram positivas para T. gondii com títulos de 1:64 (32) e 1:256 (cinco). Para a pesquisa da presença do agente no leite, foram coletadas 128 amostras de sangue das ovelhas em período de lactação, que foram processadas pela RIFI (≥1:64) das quais 42 (32,8%) foram positivas, com títulos 1:64 (26), 1:256 (12), 1:1024 (três) e 1:4096 (um). Para a pesquisa do parasito no leite foram empregadas as técnicas do bioensaio em camundongos (22 amostras de leite de oito ovelhas com títulos de anticorpos contra T. gondii ≥256) e da PCR, para a 12 13 pesquisa de T. gondii nos cérebros dos camundongos inoculados no bioensaio e também diretamente do leite (108 amostras obtidas de 42 ovelhas soropositivas (≥64) em diferentes períodos de lactação - 40, 90 e 120 dias). Foram utilizados os primers SAG2R4 e SAG2F4. Das 42 ovelhas lactantes e soropositivas para T. gondii foi possível detectar DNA do parasito no leite de 30,95% (13/42) dos animais. No bioensaio não foi possível o isolamento, entretanto DNA do agente foi detectado no cérebro dos camundongos inoculados com leite de oito ovelhas (uma amostra do 45º dia de lactação e sete na coleta do dia 90). Diretamente do leite, DNA do parasito foi detectado em amostras da segunda coleta (90 dias de lactação) em cinco animais. As amostras positivas na PCR foram sequenciadas e os resultados confirmaram identidade ≥97% com o antígeno de membrana gene P22 de T. gondii. Verificou-se que a ocorrência de anticorpos contra T. gondii em ovinos com aptidão leiteira, do Oeste de Santa Catarina é menor quando comparada com a observada em ovinos de corte no Estado e que o DNA de T. gondii está presente no leite de ovelhas, representando uma possível via de transmissão para o ser humano, por meio do consumo do leite in natura e/ou derivados, além da possibilidade da transmissão via lactogênica para cordeiros

Ce travail de thèse explore les aspects organisationnels de l’accompagnement local de la transition agroécologique. Cet accompagnement nécessite d’articuler différents processus individuels et collectifs de transformation des activités de la production et du développement agricole. En construisant un dispositif de recherche-action au sein d’un projet de transition agroécologique porté par une association d’éleveurs et conseillers dans le rayon de Roquefort, nous mettons en oeuvre avec eux une forme d’expérimentation sociale qui nous permet de comprendre le problème de l’accompagnement de la transition à la fois sur le plan théorique et pratique. Dans notre cas, l’articulation des transformations individuelles et collectives a été permise par un travail de co-conception entre éleveurs et conseillers des outils de l’accompagnement des changements dans les fermes. Ce processus a permis de débattre de la diversité des modèles agricoles et des représentations des acteurs de la transition agroécologique au sein du groupe, ainsi que d’engager conjointement éleveurs et conseillers dans la transformation de leurs pratiques. Ces transformations ont été d'autant plus facilitées que la coconception a été envisagée comme un processus dialogique entre conception et expérimentation dans différentes situations réelles d’usage dans les fermes. A l’issue de ce travail, nous proposons une approche pragmatiste pour accompagner localement la transition agroécologique / We explore in this research the organizational dimensions of agroecological transition and the ways to support it locally. The support of agroecological transition requires connecting differentprocesses of individual and collective transformations of agricultural development and production activities. We design a device for action reseach within an agroecological transition project, carriedby a farmers and advisers association in the Roquefort area. We implement with them a social experiment to explore this problem both from theoretical and practical point of view. In our casethe connection between individual and collective transformation of participant activities required farmers and advisers to design together tools to accompany the agroecological transition on farms. This process allowed the debate about the diversity of agricultural models and representations that actors have regarding agroecological transition. It as well allows engaging advisers and farmers jointly in the agroecological transition. These transformations have been enhanced by the fact that the co-design process was organized as a dialogical process between design and experimentation of the tools in diverse real situations of use on farms. At the end of this journey, we propose to develop a pragmatist approach to accompany locally the agroecological transition