[Investigations of a controlled, decision tree based procedure for Selective Dry Cow Treatment in Bavarian dairy farms]. / Untersuchungen zu einem kontrollierten, entscheidungsbaumbasierten Verfahren des Selektiven Trockenstellens in Bayerischen Milchviehbetrieben.

OBJECTIVE: Four parameters of a decision tree for Selective Dry Cow Treatment (SDCT), examined in a previous study, were analyzed regarding their efficacy in detecting cows for dry cow treatment (DCT, use of intramammary antimicrobials). This study set out to review wether all parameters (somatic cell count [SCC≥ 200 000 SC/ml 3 months' milk yield recordings prior dry off (DO)], clinical mastitis history during lactation [≥1 CM], culturing [14d prior DO, detection of major pathogens] and California-Mastitis-Test [CMT, > rate 1/+ at DO]) are necessary for accurate decision making, whether there are possible alternatives to replace culturing, and whether a simplified model could replace the decision tree. MATERIAL AND METHODS: Records of 18 Bavarian dairy farms from June 2015 to August 2017 were processed. Data analysis was carried out by means of descriptive statistics, as well as employing a binary cost sensitive classification tree and logit-models. For statistical analyses the outcomes of the full 4-parameter decision tree were taken as ground truth. RESULTS: 848 drying off procedures in 739 dairy cows (CDO) were included. SCC and CMT selected 88.1%, in combination with CM 95.6% of the cows that received DCT (n=494). Without culturing, 22 (4.4%) with major pathogens (8x Staphylococcus [S.] aureus) infected CDO would have been misclassified as not needing DCT. The average of geometric mean SCC (within 100 d prior DO) for CDO with negative results in culturing was<100 000 SC/ml milk, 100 000-150 000 SC/ml for CDO infected with minor pathogens, and ≥ 150 000 SC/ml for CDO infected with major pathogens (excluding S.aureus). Using SCC during lactation (at least 1x > 200 000 SC/ml) and positive CMT to select CDO for DCT, contrary to the decision tree, 37 CDO (4.4%) would have been treated "incorrectly without" and 43 CDO (5.1%) "unnecessarily with" DCT. Modifications were identified, such as SCC<131 000 SC/ml within 100 d prior to DO for detecting CDO with no growth or minor pathogens in culturing. The best model for grading CDO for or against DCT (CDO without CM and SCC<200 000 SC/ml [last 3 months prior DO]) had metrics of AUC=0.74, Accuracy=0.778, balanced Accuracy=0.63, Sensitivity=0.92 and Specificity=0.33. CONCLUSIONS: Combining the decision tree's parameters SCC, CMT and CM renders suitable selection criteria under the conditions of this study. When omitting culturing, lower thresholds for SCC should be considered for each farm individually to select CDO for DCT. Nonetheless, the most accurate model could not replace the full decision tree.

[Veterinary Herd Health Management and Selective Dry Cow Treatment in Germany - Results of a survey among farm veterinarians]. / Integrierte Tierärztliche Bestandsbetreuung und Selektives Trockenstellen in Deutschland.

OBJECTIVE: The aim of the survey was to evaluate the development and implementation of Veterinary Herd Health Management (VHHM), as well as Selective Dry Cow Treatment (SDCT), in German veterinary practices and dairy farms. Furthermore, this survey set out to compare and contrast veterinary practitioners that utilize VHHM in relation to SDCT with those that do not. MATERIAL AND METHODS: The survey (n=600) was distributed to veterinary livestock practitioners at 7 advanced training courses. Participation was voluntary and anonymous. Data analysis was carried out by means of descriptive statistics as well as by linear and logistic regression. RESULTS: The response rate amounted to 39.3% (n=236). 54.2% (n=128) of the veterinarians reported that they conduct VHHM. Procedures for SDCT were used on farms overseen by 75% (n=177) of the vets. Different decision criteria applied at herd (81.6%, n=142) and at individual cow level (97.7%, n=172) respectively. A performance review of SDCT was carried out more frequently on farms of veterinarians that practice VHHM (66%, n=66) than those that do not (41%, n=28). An increase in the number of farms conducting VHHM was associated with an increase in the proportion of farms using SDCT. An increase of the probability of good udder health was associated with SDCT farms that also apply VHHM (OR: 1.025; p<0.05). The provision of consultation for problems arising during the dry period (OR: 3.639; p<0.05), the frequency of veterinarians addressing SDCT with farmers (OR: 1,595; p<0,05) and vice versa (OR: 1,538; p<0.05), as well as frequency of consultation for drying off management (OR: 1,608; p<0.05) had an positive impact on the likelihood of SDCT being implemented on a farm and whether this process was ultimately successful. CONCLUSIONS: According to available data, both VHHM and SDCT are established parts of veterinary practice in bovine care. In practice, SDCT is partially conducted within the framework of a controlled procedure including a performance review. The implementation of VHHM has an effect on the number of farms performing SDCT as well as on udder health where VHHM and SDCT are combined on a farm. The range and frequency of consultation by veterinarians have a significant influence on a reduction of use of antibiotics by implementation of SDCT.