ALGUNOS FACTORES DE RIESGO EN NEOSPOROSIS BOVINA Y SU RELACIÓN CON LA SEROPREVALENCIA Y TASA DE GESTACIÓN EN EL ESTADO DE VERACRUZ, MÉXICO

Although bovine neosporosis causes reproductive, productive and economic losses in livestock around the world, there is no treatment or immunogen capable of healing or preventing this disease. It is important to investigate the seroprevalence (SP) of neosporosis due to the frequent purchase of breeding stock without knowing its health status and poor hygiene practices and handling during milking in production units (PU) with greater or less technification. The objectives were to determine the SP of neosporosis in bovine (Bos taurus x Bos indicus) PU from three Municipalities of the center zone of the State of Veracruz, Mexico, and to determine whether the pregnancy rate (PR) is affected by the SP of neosporosis. In 2013, a blood serum analysis for neosporosis detection was applied to 139 cows from seven PU with an ELISA test kit (IDEXX Laboratories). The SP of neosporosis was coded as 1 when the cow resulted seropositive; otherwise, it was coded as 0. The statistical analysis for the SP of neosporosis was carried out with the GENMOD procedure of SAS, considering a logit link function for the binomial distribution. The PR was coded as 1 when a cow was diagnosed pregnant; otherwise, it was coded as 0. The analysis for PR was also performed with the GENMOD procedure of SAS, assuming a logit link function. The statistical model included the effects of zoo-sanitary status (i.e. seropositive/seronegative to Neospora caninum) and PU. The PU variable affected (P<0.05) the SP of neosporosis. The SP of neosporosis of the bovines from the PU located in the north (San Rafael Municipality; PU2: 0.03 ± 0.035; PU7: 0.10 ± 0.067 and PU3: 0.15 ± 0.080) were lower than those from the PU located in the south (Medellin and Cotaxtla Municipalities; PU5: 0.41 ± 0.119; PU1: 0.32 ± 0.107; PU6: 0.30 ± 0.096; and PU4: 0.25 ± 0.097). The odds ratios indicated that the bovines from the PU located in the north had 5.9 times less risk (P<0.01) of being seropositive to N. caninum than those from the PU located in the south of the central zone of the State of Veracruz. There was no difference (P>0.05) in PR between seropositive and seronegative cows. N. caninum antibodies were found in all the PU of the three Municipalities of the central zone of the State of Veracruz. It is concluded that the bovines from the central region of the State of Veracruz have antibodies against N. caninum, where PU and geographical location (north or south) are factors that influenced the SP of neosporosis. The zoo-sanitary status did not influence PR.