Field vaccination of cattle using a bivalent modified-live vaccine against bluetongue virus serotypes 2 and 9: effect on milk production.
To evaluate the effect of bluetongue (BT) vaccination on milk production in cattle, 30 cows at various stages of gestation were vaccinated using a bivalent bluetongue virus serotype 2 (BTV-2) and BTV-9 modified-live vaccine produced by Onderstepoort Biological Products in South Africa. A second group of 30 pregnant cows was used unvaccinated controls. Blood samples were taken from all animals three times a week for two months. Virus titres were determined and the daily milk production of each cow was quantitatively and qualitatively evaluated. From 27 of the 30 vaccinated cows, BTV was isolated from day 4 to day 28 post vaccination. BTV vaccination had no effect on milk production, somatic cell count, pH, milk fat, protein and lactose content. It is concluded that the bivalent BTV-2/BTV-9 modified-live vaccine does not affect milk production in cows.
Monaco
F
F
Istituto Zooprofilattico Sperimentale, dell'Abruzzo e del Molise G. Caporale, via Campo Boario, 64100 Teramo, Italy.
De Luca
N
N
Morelli
D
D
Pisciella
M
M
Palmarini
S
S
Di Giandomenico
M
M
Savini
G
G