ABSTRACT
Chlamydial infections in cattle are mostly subclinical and have been linked to disease by association rather than by experimental proof. The aim of this study was to identify indicators for estimating the probability of chlamydial infection in German dairy cattle. Variables identified as significant risk factors were narrowed down and used alongside health and/or performance data from a previous study to create models using logistic regression. The database used included 100 randomly selected herds (1074 cows). Perinatal deaths, separate calving pens, and type of insemination were strongly associated with infection status. Using the regression equation, 53/61 Chlamydia positive herds and 33/39 negative herds were correctly classified. The main indicators identified by this study can be used as a supporting tool for identifying dairy herds at risk of chlamydial infections and for developing control programmes.
Subject(s)
Animal Husbandry/methods , Cattle Diseases/microbiology , Chlamydia Infections/veterinary , Animals , Cattle , Cattle Diseases/epidemiology , Cattle Diseases/etiology , Chlamydia Infections/etiology , Chlamydia Infections/prevention & control , Dairying , Female , Germany/epidemiology , Risk FactorsABSTRACT
During the recent bluetongue virus (BTV) outbreak in Germany, semen quality in bulls naturally infected with BTV-serotype 8 was evaluated. Bluetongue status was assessed by both serology and polymerase chain reaction (PCR). Six bulls became BTV-PCR positive between September and November 2007 without showing clinical signs. Between April and May 2008, all six bulls were PCR negative but remained seropositive. Semen data from non-infected test bulls recorded between 2006 and 2007 were matched for season and age and used as controls. BTV-8 infection had no effect on sperm volume and concentration, but reduced sperm motility was seen after thawing (January-August 2008: 44.1 ± 12.7% vs. 58.0 ± 7.9% in the uninfected bulls; P < 0.001). Malformed sperm in both in fresh and thawed semen from BTV-positive animals was above the 20% permitted maximal limit from December 2007 to February 2008. Infection with BTV-8 transiently impaired semen quality in bulls.
