title: Use of inline measures of l-lactate dehydrogenase for classification of posttreatment mammary Staphylococcus aureus infection status in dairy cows.
abstract: An automated method for determining whether dairy cows with subclinical mammary infections recover after antibiotic treatment would be a useful tool in dairy production. For that purpose, inline l-lactate dehydrogenase (LDH) measurements was modeled using a dynamic linear model; the variance parameters were estimated using the expectation-maximization algorithm. The method used to classify cows as infected or uninfected was based on a multiprocess Kalman filter. Two learning data sets were created: infected and uninfected. The infected data set consisted of records from 48 cows with subclinical Staphylococcus aureus infection from 4 herds collected in 2010. The uninfected data set came from 35 uninfected cows collected during 2013 from 2 herds. Bacteriological culturing was used as gold standard. To test the model, we collected data from the 48 infected cows 50 d after antibiotic treatment. As a result of the treatment, this test data set consisted of 25 cows that still had a subclinical infection and 23 cows that were recovered. Model sensitivity was 36.0% and specificity was 82.6%. To a large extent, l-lactate dehydrogenase reflected the cow's immune response to the presence of pathogens in the udder. However, cows that were classified correctly before treatment had a better chance of correct classification after treatment. This indicated a variation between cows in immune response to subclinical mammary infection that may complicate the detection of subclinically infected cows and determination of recovery.
authors: Department of Animal Science, Aarhus University, DK-8830 Tjele, Denmark. Electronic address: carina.jorgensen@anis.au.dk.
authors: C Hildebrandt
authors: CH
authors: Jørgensen
authors: Department of Large Animal Sciences, University of Copenhagen, DK-1870 Frederiksberg C, Denmark.
authors: A R
authors: AR
authors: Kristensen
authors: Department of Animal Science, Aarhus University, DK-8830 Tjele, Denmark.
authors: S
authors: S
authors: Østergaard
authors: Department of Animal Science, Aarhus University, DK-8830 Tjele, Denmark.
authors: T W
authors: TW
authors: Bennedsgaard
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D002417:Cattle; D005260:Female; D007770:L-Lactate Dehydrogenase / Q000032:analysis*; D016014:Linear Models; D008321:Mammary Glands, Animal / Q000187:drug effects / Q000382:microbiology*; D008414:Mastitis, Bovine / Q000188:drug therapy* / Q000382:microbiology; D008892:Milk / Q000382:microbiology; D012680:Sensitivity and Specificity; D013203:Staphylococcal Infections / Q000188:drug therapy / Q000662:veterinary*; D013211:Staphylococcus aureus / Q000187:drug effects / Q000201:enzymology / Q000302:isolation & purification*
chemical_list: D000900:Anti-Bacterial Agents; D007770:L-Lactate Dehydrogenase
keywords: dairy cow; l-lactate dehydrogenase; mastitis; multiprocess model