title: Maedi-visna impact on productivity in Quebec sheep flocks (Canada).
abstract: An epidemiological study was conducted to determine the impact of maedi-visna (MV) seropositivity on productivity in commercial sheep flocks of the province of Quebec, Canada. A total of 1734 ewes and 220 rams were selected randomly from 29 flocks distributed in the Bas-St-Laurent and Estrie regions. Serostatus was determined with an enzyme-linked immunosorbent assay (ELISA) using recombinant proteins.Flock-specific, animal-level seroprevalence varied from 3 to 70% (median=29%). Seroprevalence increased with age and size of the flock, and was higher in ewes relative to rams (but was not associated with body score). A decrease of 0.94 kg per lamb in weaning weight was seen only for lambs raised by seropositive ewes >/=4 years old, and seropositivity in ewes of any age was associated with an increase in 0-30 days lamb-mortality (OR: 1.65). The impact of MV infection on weaning weight and lamb mortality did not vary between flocks, and seropositivity in ewes was not associated with litter size or lamb's birth weight.
authors.affiliation: Faculté de Médecine Vétérinaire, Université de Montréal, 3200 Rue Sicotte, C.P. 5000, Saint-Hyacinthe, Que., Canada J2S 7C6. julie.arsenault@umontreal.ca
authors.forename: Julie
authors.initials: J
authors.lastname: Arsenault
authors.forename: Pascal
authors.initials: P
authors.lastname: Dubreuil
authors.forename: Christiane
authors.initials: C
authors.lastname: Girard
authors.forename: Carole
authors.initials: C
authors.lastname: Simard
authors.forename: Denise
authors.initials: D
authors.lastname: Bélanger
mesh_terms: D000375:Aging; D000818:Animals; D001724:Birth Weight; D001835:Body Weight; D005260:Female; D008098:Litter Size; D008297:Male; D011021:Pneumonia, Progressive Interstitial, of Sheep / Q000453:epidemiology* / Q000401:mortality; D011156:Population Density; D011792:Quebec / Q000453:epidemiology; D012307:Risk Factors; D016036:Seroepidemiologic Studies; D012727:Sex Characteristics; D034561:Sheep, Domestic / Q000254:growth & development / Q000502:physiology* / Q000821:virology*; D014790:Visna-maedi virus / Q000502:physiology*