A sample of 883 calving cows with complete demographic
data from 22 herds was considered for analyses.
Among them, 18.3% were detected shedders and 42.2%
were seropositive. There was a mean of 40 cows by herd
(Q1 = 26; Q2 = 51) and a median age at calving of 4.7 years
(Q1 = 3.4; Q2 = 5.6). The distribution of shedder cows
according to their different shedding level is displayed in
Table 1.
The risk of being detected shedder at calving time
associated with the medical strategies received by the
cows is displayed in Table 2. No interaction between
medical strategies was found to be significant (P > 0.05).
Vaccination strategies were not significantly associated
with shedding status in cows (P > 0.05), whereas tetracycline
used once at drying off was associated with a lower
risk of shedding at calving (OR = 0.40, CI 95% [0.21–0.75]).
A second injection does not improve the (OR = 0.50, CI 95%