A longitudinal study on the effects of maternal and offspring seropositivity for Neospora caninum on birth weight, survival, reproductive performance and abortion in the offspring.

Neospora caninum (N. caninum) is known as a source of economic losses due to causing abortion in cows. Additionally, it is well-established that this parasite can be vertically transmitted from the dam to the fetus through placenta. There is, however, little and contradictory information about whether transplacental infection of the offspring during prenatal period could impair its survival and reproductive performance during postnatal period, and the current study was conducted to address this issue. To this end, seropositivity of heifer dams (n = 430) and their offspring were ascertained at the age of 12 and 3 months, respectively. Based on the serologic results, there were four categories of female offspring including: 1) seronegative offspring born to seronegative dams (n = 183), 2) seropositive offspring born to seronegative dams (n = 59), 3) seronegative offspring born to seropositive dams (n = 29), and 4) seropositive offspring born to seropositive dams (n = 30). The birth weight, survival, reproductive performance and abortion of these offspring were studied from birth to culling. Maternal seropositivity was positively associated with offspring seropositivity (P < 0.05). Birth weight did not differ among offspring in various categories (P > 0.05). Seropositive offspring born to seronegative dams and seronegative offspring born to seropositive dams had inferior cumulative reproductive performance over life as compared to seronegative offspring born to seronegative dams (P < 0.05). Seropositive offspring had greater cumulative abortion risk and shorter lifespan than seronegative offspring regardless of their maternal serologic condition (P < 0.05). In conclusion, the present study showed that maternal seropositivity for N. caninum increased the risk of seropositivity in the offspring, and seropositive offspring had increased abortion risk and decreased longevity. Maternal seropositivity for N. caninum could have developmental effects on cumulative reproductive performance of the offspring that were not vertically infected.