Oral and Poster Abstracts

area. The importance of BHV-1 in etiology of respiratory disease
complex in beef calves was conducted in the years 2005-2007. It was
carried out on 12 fattening farms (250-500 animals per herd) by
determining seroconversion after enzootic pneumonia outbreak,
examining the presence of antibody titer before slaughtering and the
virus isolation from nasal swabs was also done at the beginning of an
acute respiratory infection. A characteristic feature common for all the
farms is that new animals are introduced several times a year and
therefore it is impossible to avoid simultaneous presence of different
aged animals, what gives a possibility for long retention of the virus in
a herd. Beef farms in Vojvodina purchase young calves from mountain
regions, where the prevalence of BHV-1 in adult animals is even 45%.
On all the farms the animals were clinically examined; out of total
number the blood was sampled from 3-10%, most of them were sick,
chronically sick or recovered from the respiratory syndrome. The
second sampling, for determining seroconversion, was carried out 3-4
weeks after the first one. In all the fattening farms enzooty of
bronchopneumonia was present. Clinical symptoms were: increased
body temperature, weak serous nasal discharge, coughing and
dyspnoea. BHV-1 seroconversion in totally recovered and animals
chronically ill from bronchopneumonia was not determined in all the
examined herds. In newly arrived calves seroprevalence on BHV-1
ranged from 0-10.56%. At the end of fattening period antibodies
against BHV-1 ranged from 0-100%, depending on a herd. However,
BHV-1 was not isolated during acute infection. From the obtained
results it may be concluded that, currently, BHV-1 is not of great
importance for developing respiratory syndrome in the herds of beef
calves, what was not the case in past decades, so the infection is
subclinically present. In fact, in all the beef farms, after the recovery
from the disease, immuno-response towards BRSV and Pi-3 was
determined. In the lungs of dead animals only mycoplasma was
determined, or mycoplasma with bacteria.
Key words: BHV-1, beef, respiratory syndrome, Vojvodina
691 Effect of Vaccination against Leptospira on Dairy Farm
Reproduction Indexes
D. Ruiz Di Genova
COVAP, Bovine Technical Services, Pozoblanco, Spain
Leptospirosis is a worldwide occurring disease, that when caused by
serovars adapted to dairy cows (serovar Hardjo) produce chronic
infections, where the signs are less evident.
Objective: To assess the effect of vaccination against Leptospira
interrogans serovar Hardjo on the reproduction indexes.
Materials and Methods: The study includes 9 dairy farms (mean 70
cows/farm), in southern Spain with complete reproductive records
comprising a year before the first leptospira vaccination and a year
afterwards. In seven farms, serological diagnosis of leptospirosis was
performed by MAT (microagglutination test) for serovar hardjo, prior
to vaccination. A positive farm was considered when presenting one
animal with a titter > 1/10. Another two farms were vaccinated due to
the clinical suspicion, after ruling out other reproductive diseases.The
monthly conception rates and first service conception rates were used
as fertility indexes, comparing results obtained one year before
vaccination with results obtained on the year afterwards.Cumulative
data were analyzed using logistic regression, which allows to establish
a model for dicotomic results (pregnant/not pregnant). The result is
expressed as an odds ratio indicating the different occurrence
probability of one or the other event, that is, the probability of
pregnancy after one service, before and after vaccination.
Results: The probability of pregnancy in vaccinated cows was 1,25
times higher than in not vaccinated ones. (OR=1,25399, EE=0,0673;
P=0,0008), with the “vaccination” variable accounting for 21% of this
variation in fertility. In the first-calving cows the probability of
conception increased 1,70 times after vaccination (P