Évaluation de la prévalence individuelle et de troupeau de quatre pathogènes d'importance dans les troupeaux laitiers biologiques du Québec

INTRODUCTION La production biologique contribue de façon significative aux défis du développement durable. Les infections à Mycobacterium avium sous-espèce paratuberculosis (MAP), Neospora caninum (NC), au virus de la diarrhée virale bovine (BVD) et au virus de la rhinotrachéite infectieuse bovine (IBR) sont bien reconnues pour affecter de manière significative la production dans les élevages laitiers. Il n’existe toutefois aucune donnée sur l’importance de ces pathogènes dans les troupeaux biologiques. HYPOTHESE Ces quatre pathogènes sont présents dans les troupeaux laitiers biologiques, mais leur prévalence est moindre par rapport à l’élevage conventionnel. OBJECTIFS Estimer les séroprévalences de NC, MAP, BVD, IBR dans les troupeaux laitiers biologiques québécois. MÉTHODOLOGIE Dans la province du Québec, 60 troupeaux laitiers biologiques ont été sélectionnés aléatoirement. Un échantillon sanguin a été prélevé sur 30 vaches adultes, pour l’évaluation de NC et MAP, et sur 5 animaux plus de 6 mois non vaccinés, pour l’évaluation de BVD et IBR. Une détection d’anticorps par ELISA, pour NC et MAP, et par séroneutralisation pour BVD et IBR a été réalisée sur les sérums obtenus. Un questionnaire a été rempli par chaque éleveur. RÉSULTATS La séroprévalence individuelle de NC et MAP, avec un intervalle de confiance de 95%, étaient de 4.1% (3.2%-5.2%) et 0.8% respectivement (0.0%-1.3%). La séroprévalence de troupeau de NC, MAP, BVD, IBR, si au moins un animal est positif dans un troupeau étaient de 50.8%, 20.3%, 37.3%, 31.0% respectivement. Ces séroprévalences étaient de 30.5%, 3.4%, 28.8% et 18.9%, respectivement, si au moins deux animaux sont positifs. La taille du troupeau a un effet significatif sur le statut de BVD (p=0.02) et il y a une bonne corrélation entre le statut BVD et IBR (Kappa-0.54). DISCUSSION/CONCLUSION La séroprévalence individuelle de NC, MAP, IBR semblent être moindre dans les troupeaux laitiers biologiques comparativement au conventionnel. Il ne semble pas y avoir de grandes différences entre la séroprévalence du BVD des troupeaux biologiques et celle des conventionnels.INTRODUCTION Organic herds are important component of sustainable development. Mycobacterium avium subspecies paratuberculosis (MAP), Neospora caninum (NC), bovine viral diarrhoea (BVD) virus and infectious bovine rhinotracheitis (IBR) virus infections are well known to have major impact on dairy production. However, there are actually no data on the prevalence of these pathogens in organic dairy herds. HYPOTHESIS These four pathogens are present among cattle organic herds but their prevalence is less than among conventional cattle herds. OBJECTIVE To evaluate the seroprevalence of NC, MAP, BVD, IBR in cattle organic herds in Québec province. METHODOLOGY In the province of Québec, 60 organic herds were randomly sampled. Thirty adult cows, to estimate NC and MAP, and 5 unvaccinated animals more than 6 months old, for BVD and IBR, were bled. An ELISA test, for NC and MAP, and seroneutralisation test for BVD and IBR were used to analyse the serum. A questionnaire was filled in by farmers. RESULTS Individual prevalence of NC and MAP (IC=95%) were 4.1% (3.2%-5.2%) and 0.8% (0.0%-1.3%) respectively. Herd level prevalence of NC, MAP, BVD, IBR, based on a herd-test cut point of 1 positive animal, were 50.8%, 20.3%, 37.3%, and 31.0% respectively. Based on a herd-test cut point of 2 positive animals, these prevalence were 30.5%, 3.4%, 28.8% and 18.9% respectively. Herd size was significantly associated with BVD herd prevalence (p=0.02).... There was a good correlation between herd prevalence of BVD and herd prevalence of IBR (Kappa=0.54). DISCUSSION/CONCLUSION Prevalence of NC, MAP, and IBR seem to be less among cattle organic herds than in cattle conventional herds. It seems that there is no difference between prevalence of BVD among organic herds and conventional herds

Extinction vulnerability of tropical montane endemism from warming and upslope displacement: a preliminary appraisal for the highest massif in Madagascar

One of the predicted biological responses to climate warming is the upslope displacement of species distributions. In the tropics, because montane assemblages frequently include local endemics that are distributed close to summits, these species may be especially vulnerable to experiencing complete habitat loss from warming. However, there is currently a dearth of information available for tropical regions. Here, we present a preliminary appraisal of this extinction threat using the herpetological assemblage of the Tsaratanana Massif in northern Madagascar (the island's highest massif), which is rich with montane endemism. We present meteorological evidence (individual and combined regional weather station data and reanalysis forecast data) for recent warming in Madagascar, and show that this trend is consistent with recent climate model simulations. Using standard moist adiabatic lapse rates, these observed meteorological warming trends in northern Madagascar predict upslope species displacement of 17–74 m per decade between 1993 and 2003. Over this same period, we also report preliminary data supporting a trend for upslope distribution movements, based on two surveys we completed at Tsaratanana. For 30 species, representing five families of reptiles and amphibians, we found overall mean shifts in elevational midpoint of 19–51 m upslope (mean lower elevation limit 29–114 m; mean upper elevation limit −8 to 53 m). We also found upslope trends in mean and median elevational observations in seven and six of nine species analysed. Phenological differences between these surveys do not appear to be substantial, but these upslope shifts are consistent with the predictions based on meteorological warming. An elevational range displacement analysis projects complete habitat loss for three species below the 2 °C ‘dangerous’ warming threshold. One of these species is not contracting its distribution, but the other two were not resampled in 2003. A preliminary review of the other massifs in Madagascar indicates potential similar vulnerability to habitat loss and upslope extinction. Consequently, we urgently recommend additional elevational surveys for these and other tropical montane assemblages, which should also include, when possible, the monitoring of local meteorological conditions and habitat change.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/74789/1/j.1365-2486.2008.01596.x.pd