Serological study of the frequency of leptospiral infections among dairy cows in farms with suboptimal reproductive efficiency in Galicia, Spain
Abstract
Between March 1996 and September 1997, 15 farms located in Galicia (NW Spain) and experiencing suboptimal reproductive efficiency were visited and blood samples were obtained from all the lactating cows (n=442). Additionally, 1060 samples were obtained monthly from a cohort of 219 lactating cows belonging to nine of the farms between March 1996 and April 1997. All the samples were tested by microscopic agglutination (MAT) using live antigens representing the following Leptospira interrogans serogroups: Australis, Autumnalis, Ballum, Canicola, Grippotyphosa, Icterohaemorrhagiae, Louisiana, Pomona, Sejroe, Shermani and Tarassovi. Eighty-one of the 442 cows were positive against one or more serogroups (P=18.33%). Serologically, L. bratislava and L. grippotyphosa were detected as the most prevalent serovars (P=7.92 and 7.69%, respectively) and as the serovars against which the probability of seroconversion was highest (P=0.27 and 0.25, for a 12-month period, respectively) among those studied. The proportional hazards regression method was used for evaluating the seasonal trend of seroconversions against these two serovars. The risk of seroconversion against L. grippotyphosa was significantly higher during spring. The risk of seroco...Continue Reading
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