Abstract
Simple SummaryThe vast majority of all antibiotics used in the dairy industry are applied to control mastitis, one of the most important infectious diseases in dairy cows. The aim of this systematic review and meta-analysis is to evaluate the efficacy of selective dry cow treatment vs. blanket dry cow treatment (i.e., antibiotic treatment of all quarters in all cows) on different measures of udder health as well as antibiotic use at drying-off. In this way, it could contribute to minimizing antimicrobial agent usage, which is increasingly criticized based on a growing spread of antimicrobial resistance and its negative consequences for public health.The objectives of this paper were (i) to perform a systematic review of the literature over the last 21 yr and (ii) to evaluate the efficacy of selective dry cow treatment (SDCT) vs. blanket dry cow treatment (BDCT) in dairy cows regarding the risk of intramammary infection (IMI) after calving, new IMI risk after calving, cure risk during the dry period, and a reduction in antibiotic use at drying-off by meta-analysis. The systematic search was carried out using the databases PubMed, CAB Direct, and ScienceDirect. A meta-analytical assessment was performed for each outcome of interest using random-effects models, and the relative risk (RR) for IMI and cure or the pooled proportion for antibiotic use was calculated. The final number of included studies was n = 3 for IMI risk after calving and n = 5 for new IMI risk after calving, cure risk during the dry period, and antibiotic use. The RR levels for IMI (RR, 95% confidence interval [CI]: 1.02, 0.94–1.11; p = 0.592), new IMI (RR, 95% CI: 1.06, 0.94–1.20; p = 0.994), and cure (RR, 95% CI: 1.00, 0.97–1.02; p = 0.661) did not differ significantly between SDCT and BDCT. Substantial heterogeneity was observed between the trials regarding the pooled proportion of antibiotic use within the SDCT groups (I2 = 97.7%; p < 0.001). This meta-analysis provides evidence that SDCT seems to be an adequate alternative to BDCT regarding udder health with a simultaneous reduction in antibiotic use. Limitations might arise because of the small number of studies included.
Highlights
Mastitis is one of the most important infectious diseases in dairy cows worldwide, responsible for substantial economic losses and detrimental effects on ruminant welfare arising from reduced milk yield and fertility as well as increased use of antimicrobial agents and higher culling risk [1,2,3,4,5]
Various studies have been conducted to compare the efficacy between blanket dry cow treatment (BDCT) and selective dry cow treatment (SDCT) as an alternative concept, where antibiotic treatments are allocated to individual cows or quarters known to have or suspected of having an intramammary infection (IMI)
Out of 309 articles that were initially screened by title and abstract, 80 full texts were reviewed, with 70 studies found to not fulfill the inclusion criteria and the remaining 10 articles being eligible as they investigated the effect of SDCT
Summary
Mastitis is one of the most important infectious diseases in dairy cows worldwide, responsible for substantial economic losses and detrimental effects on ruminant welfare arising from reduced milk yield and fertility as well as increased use of antimicrobial agents and higher culling risk [1,2,3,4,5]. Because resistance genes can be found for those antibiotics frequently used for dry cow treatment (DCT), such as β-lactam antibiotics, third-generation cephalosporins, and aminoglycosides [10,11], the European Commission recommends that routine antibiotic treatment of all quarters in all cows at drying-off regardless of their infection status (i.e., blanket dry cow treatment, BDCT) should be avoided. It has been shown, that intramammary antibiotic treatment can improve udder health in early lactation [10,11,12,13]. The selection is based on test results of rapid culture systems used before drying-off (culture-guided SDCT, cSDCT) or by using individual cow data, such as somatic cell count (SCC) and history of clinical mastitis (CM) cases, in algorithms
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