The aim of this study was to determine the variation of milk urea nitrogen (MUN) concentration according to milk yield and milk protein in Holstein cows in Boyacá, Colombia. Data previously collected (n=4901) over two years were used. Univariate analysis of variance was performed with the variables milk yield (l/day) and milk protein (%) as independent variables and the concentration of MUN as the dependent variable. In addition, a simple linear correlation analysis was performed between each variable. The results showed that MUN values are higher when milk yield is lower, but no statistical differences were found for MUN concentration according to milk protein content. Weak and negative correlation was found between milk yield and MUN concentration, but no significant correlation was found between milk protein and MUN concentration.

The aim of the present study was to determine the presence of antibodies against Neospora caninum in a dairy herd in the municipality of Toca, Colombia. Blood samples (n=100) were collected from females between 1 and 9 years of age. The animals were selected through simple random method of prospective cross-cut. The serum samples were processed using a commercial indirect ELISA kit. The prevalence of antibodies anti-N. caninum was 64%. The association between positive animals with history of abortion and parity was statistically significant (p<0.05), while the association with age, reproductive status and repeat breeding was not significant.

El presente estudio tuvo como objetivo determinar la presencia de anticuerpos contra Neospora caninum en un hato lechero del municipio de Toca, Colombia. Se tomaron 100 muestras de sangre de bovinos de 1 a 9 años de edad, seleccionados mediante un método aleatorio simple de corte transversal prospectivo. Las muestras de suero fueron procesadas mediante un kit comercial de ELISA indirecta. La seroprevalencia de anticuerpos anti-N. caninum fue de 64%. La asociación entre animales positivos con historia de abortos y número de partos fue estadísticamente significativa (p<0.05), en tanto que la asociación con la edad, estado reproductivo y repetición de celos no fue significativa.