Diet and cooling interactions on physiological responses of grazing dairy cows, milk production and composition.

The objective of this trial was to evaluate the effects of diet and cooling in the holding pen before milking on rectal temperature, respiration rate and milk production and composition. Fifty-eight lactating Holstein cows were used in a factorial split-plot design, at Rafaela Experimental Station from 12 January to 3 March 2003. The treatments were combinations of two diets: control (CD) and balanced (BD) with two levels of cooling before milking: none (NSF) and a sprinkler and fans (SF).

Fluorescence polarization assay for the diagnosis of bovine brucellosis: adaptation to field use.

A fluorescence polarization assay (FPA) was used to test whole blood samples prepared by mixing blood cells from cattle without exposure to Brucella abortus (B. abortus) with sera from animals with confirmed (bacteriologically) infection. A cut-off value between negative and positive values was initially established to be 87.

Use of Brucella abortus vaccine strain RB51 in pregnant cows after calfhood vaccination with strain 19 in Argentina.

One hundred and seven pregnant cows, which had been calfhood vaccinated with Brucella abortus strain 19 (S-19) were revaccinated with either S-19 or strain RB51 (S-RB51). All S-19-revaccinated animals seroconverted, while none of the RB51-revaccinated animals seroconverted. Two out of 25 (8%) S-19-revaccinated animals aborted, while none of the 57 RB51-revaccinated group aborted.

Validation of enzyme-linked immunosorbent assays for the diagnosis of bovine brucellosis.

The purpose of this study was to evaluate the performance of the indirect enzyme immunoassay (IELISA) and the competitive enzyme immunoassay (CELISA) for the diagnosis of bovine brucellosis in comparison to conventional serological tests routinely used in Argentina. Serum samples (n = 3500), from Brucella-free herds, from vaccinated cattle and from naturally infected cattle, were tested by the following tests: buffered antigen agglutination test (BPAT), rose bengal test (RBT), 2-mercaptoethanol test (2-ME), complement fixation test (CFT), IELISA and CELISA. Sensitivity and specificity of the BPAT, RBT, IELISA and CELISA were determined relative to the 2-ME and the CFT.

Fluorescence polarization assay: application to the diagnosis of bovine brucellosis in Argentina.

A homogeneous fluorescence polarization assay (FPIA) for detection of bovine antibody to Brucella abortus was validated in Argentina Sera were defined based on their reactivity in the buffered antigen plate agglutination test (BPAT) and the competitive enzyme immunoassay (CELISA). Sera negative in these tests were collected from farms without evidence of brucellosis (n=733). Sera positive in the two tests were collected from cattle on farms from which B.