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Maedi-visna impact on productivity in Quebec sheep flocks (Canada)

2003; Elsevier BV; Volume: 59; Issue: 3 Linguagem: Inglês

10.1016/s0167-5877(03)00086-2

1873-1716

Julie Arsenault, P. Dubreuil, Christiane Girard, Carole Simard, Denise Bélanger,

HIV Research and Treatment

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.