[Retroviroses of small ruminants: influence of infection by Maedi-Visna virus on ewe milk quality (pilot trial)]

aetiology calidad caprin caprinos cell counting contenido proteico diagnosis diagnostic etiologia etiologie ewe milk goats lait de brebis leche de oveja lipid content ovin ovinos protein content quality retroviridae sheep symptome symptoms teneur en lipides virose viroses virosis virus visna maedi visna maedi virus