The killed
vaccine is stable in storage and is an excellent stimulant
of passive antibodies in colostrums. Notwithstanding the
listed advantages, the killed vaccine has its pitfalls. It may
not provide a long-lasting immunity to the animal and can
cause allergy and vaccination reactions. The killed vaccine
may not be effective in the presence of passive colostral
immunity[44].
In study of Ortega-Mora et al., N. caninum DNA was
detected in non-extended fresh semen samples and frozen
extended semen straws by nested-PCR[20]. The molecular
method for detection of N. caninum DNA was used in their
study similar to current research.
The research of Munhoz et al. in Brazil showed that the
abortion was provoked by the protozoan N. caninum, though
this is the first report concerning cattle in the northeast
region of São Paulo state[45].
In conclusion, the results of our study and earlier
researches present that frozen semen samples, which
used for artificial insemination in Iranian Insemination
Centers, plays an important role in the spread of bovine
neosporosis. Preventing the entrance of N. caninum to
cattle is a significant aim of control programs. Based on
this data, analysis of bull’s semen samples that used for
artificial insemination to control and prevention of N.
caninum infection is very important. The final examinations
by high efficiency for diagnosis of N. caninum infection in
bull’s semen samples to reduce the economic losses of this
protozoan infection such as abortion, lost milk and meat in
dairy industries, it appear to be necessary.