Blanket Dry Cow Therapy Research Articles

Quantification of antimicrobial consumption in adult cattle on dairy herds in Flanders, Belgium, and associations with udder health, milk quality, and production performance

The main objective of this study was to quantify the (compound-specific) antimicrobial consumption (AMC) in adult cattle in a convenience sample of Flemish dairy herds. Antimicrobial consumption data were obtained between 2012 and 2013 by “garbage can audits” and expressed as antimicrobial treatment incidence (ATI), with the unit of the ATI being the number of defined daily doses animal (DDDA) used per 1,000 cow-days. Herds were stratified by DDDA into low-, medium-, and high-consuming herds to study the AMC per route of administration, and associations with parameters reflecting udder health, milk quality, and production performances were examined. The average ATI in adult dairy cattle for all compounds was 20.78 DDDA (per 1,000 cow-days). Large variation existed between herds (ranging from 8.68 to 41.62 DDDA). Fourth-generation cephalosporins were used most (4.99 DDDA), followed by penicillins (3.70 DDDA) and third-generation cephalosporins (2.95 DDDA). The average ATI of the critically important antimicrobials for human health (i.e., third- and fourth-generation cephalosporins and fluoroquinolones according to the World Organisation for Animal Health classification) was somewhat lower than the average ATI of the other antimicrobials (8.59 and 12.18 DDDA, respectively). The average ATI for intramammary treatment of (sub)clinical mastitis, for dry-cow therapy, and for systemically administered antimicrobials was 6.30, 6.89, and 7.44 DDDA, respectively. In low-consuming herds, most antimicrobials were being used for dry-cow therapy, whereas in high-consuming herds, most antimicrobials were being used as injectable or intramammary mastitis therapy. The incidence rate of treated mastitis was positively associated with ATI. Herds that applied blanket dry-cow therapy tended to have a higher ATI than herds in which cows were selectively dried off with long-acting antimicrobials. The ATI decreased with an increasing prevalence of primiparous cows.

Herd management and social variables associated with bulk tank somatic cell count in dairy herds in the eastern United States

The ability to reduce somatic cell counts (SCC) and improve milk quality depends on the effective and consistent application of established mastitis control practices. The US dairy industry continues to rely more on nonfamily labor to perform critical tasks to maintain milk quality. Thus, it is important to understand dairy producer attitudes and beliefs relative to management practices, as well as employee performance, to advance milk quality within the changing structure of the dairy industry. To assess the adoption rate of mastitis control practices in United States dairy herds, as well as assess social variables, including attitudes toward employees relative to mastitis control, a survey was sent to 1,700 dairy farms in Michigan, Pennsylvania, and Florida in January and February of 2013. The survey included questions related to 7 major areas: sociodemographics and farm characteristics, milking proficiency, milking systems, cow environment, infected cow monitoring and treatment, farm labor, and attitudes toward mastitis and related antimicrobial use. The overall response rate was 41% (21% in Florida, 39% in Michigan, and 45% in Pennsylvania). Herd size ranged from 9 to 5,800 cows. Self-reported 3-mo geometric mean bulk tank SCC (BTSCC) for all states was 194,000cells/mL. Multivariate analysis determined that proven mastitis control practices such as the use of internal teat sealants and blanket dry cow therapy, and not using water during udder preparation before milking, were associated with lower BTSCC. Additionally, farmer and manager beliefs and attitudes, including the perception of mastitis problems and the threshold of concern if BTSCC is above 300,000cells/mL, were associated with BTSCC. Ensuring strict compliance with milking protocols, giving employees a financial or other penalty if BTSCC increased, and a perceived importance of reducing labor costs were negatively associated with BTSCC in farms with nonfamily employees. These findings highlight the need for a comprehensive approach to managing mastitis, one that includes the human dimensions of management to maintain the practice of scientifically validated mastitis control practices.

Evaluation of selective dry cow treatment following on-farm culture: Milk yield and somatic cell count in the subsequent lactation

Compared with blanket dry cow therapy (DCT), the selective antimicrobial treatment of cows based upon on-farm culture results has the potential to reduce the amount of antimicrobials used in dairy production. The objective of the current study was to determine the effect of a Petrifilm (3M Canada, London, Ontario) on-farm culture-based selective DCT program on milk yield and somatic cell count (SCC) in the following lactation. A total of 729 low-SCC (<200,000 cells/mL) cows from 16 commercial dairy herds with a low bulk tank SCC (<250,000 cells/mL) were randomly assigned to receive either blanket DCT or Petrifilm-based selective DCT. Cows belonging to the blanket DCT group were infused with a commercial DCT product and an internal teat sealant (ITS) at drying off. Using composite milk samples collected on the day before drying off, cows in the selective DCT group were treated at drying off based on the results obtained by the Petrifilm on-farm culture system with DCT and ITS (Petrifilm culture positive) or ITS alone (Petrifilm culture negative). Milk test-day records for the following lactation were obtained from Dairy Herd Improvement for all cows enrolled in the trial. Repeated measures linear mixed models were used to assess the effect of study group (blanket or selective DCT) on test-day milk production and natural logarithm of SCC over the first 180 d of the subsequent lactation. According to the final multivariable models, when low-SCC cows were selectively treated with DCT at drying off based on results obtained using the Petrifilm on-farm culture system, no effect on milk production (least squares means for blanket DCT=39.3 kg vs. selective DCT=39.0 kg) or natural logarithm of SCC (least squares means for blanket DCT=3.95 vs. selective DCT=3.97) was observed in the subsequent lactation when compared with cows receiving blanket DCT. The results of this study indicate that selective DCT based on results obtained by the Petrifilm on-farm culture system enabled a reduction in the use of DCT without negatively affecting milk production and milk quality.

Evaluation of selective dry cow treatment following on-farm culture: Risk of postcalving intramammary infection and clinical mastitis in the subsequent lactation

The objective of the study was to evaluate the utility of a Petrifilm-based on-farm culture system when used to make selective antimicrobial treatment decisions on low somatic cell count cows (<200,000 cells/mL) at drying off. A total of 729 cows from 16 commercial dairy herds with a low bulk tank somatic cell count (<250,000 cells/mL) were randomly assigned to receive either blanket dry cow therapy (DCT) or Petrifilm-based selective DCT. Cows belonging to the blanket DCT group were infused with a commercial dry cow antimicrobial product and an internal teat sealant (ITS) at drying off. Using composite milk samples collected on the day before drying off, cows in the selective DCT group were treated at drying off based on the results obtained by the Petrifilm on-farm culture system with DCT + ITS (Petrifilm culture positive), or ITS alone (Petrifilm culture negative). Quarters of all cows were sampled for standard laboratory bacteriology on the day before drying off, at 3 to 4d in milk (DIM), at 5 to 18 DIM, and from the first case of clinical mastitis occurring within 120 DIM. Multilevel logistic regression was used to assess the effect of study group (blanket or selective DCT) and resulting dry cow treatment (DCT + ITS, or ITS alone) on the risk of intramammary infection (IMI) at calving and the risk of a first case of clinical mastitis between calving and 120 DIM. According to univariable analysis, no difference was observed between study groups with respect to quarter-level cure risk and new IMI risk over the dry period. Likewise, the risk of IMI at calving and the risk of clinical mastitis in the first 120 DIM was not different between quarters belonging to cows in the blanket DCT group and quarters belonging to cows in the selective DCT group. The results of this study indicate that selective DCT based on results obtained by the Petrifilm on-farm culture system achieved the same level of success with respect to treatment and prevention of IMI over the dry period as blanket DCT and did not affect the risk of clinical mastitis in the first 120d of the subsequent lactation.

Intramammary infection at calving following Petrifilm-based selective dry cow therapy

For producers motivated to reduce the use of antimicrobials on their farms, teat sealant-based selective dry-cow therapy (SDCT) offers an alternative to blanket dry-cow therapy (BDCT). Under a SDCT program, antimicrobial dry-cow preparations (DCT) are reserved for cows that are suspected, or known, to have an intramammary infection (IMI) at dry-off. Internal teat sealants (ITS) are a non-antimicrobial treatment that have been shown to be protective against new IMI during the entire dry period. Internal teat sealants are recommended for all cows as they enter the dry period, but their role is particularly important for cows not selected to receive DCT in a SDCT program. Determination of a cow's IMI status at dry-off is essential to the success of any SDCT program. Petrifilms are culture media plates that allow producers to culture milk on-farm, with results available in 24 hours. Petrifilms had a sensitivity of 85.2% and a specificity of 73.2% when used to diagnose IMIs in low somatic cell count (SCC; &lt; 200,000 cells/mL) cows at dry-off. The objective of this study was to compare IMI at calving between cows that received BDCT and cows selectively treated on the basis of Petrifilm culture results.

Preliminary results from a non-inferiority clinical trial evaluating the efficacy of three commercial dry cow mastitis preparations

Although the practice of blanket dry cow therapy (DCT) has been widely adopted in North American dairy herds, the efficacy of various antimicrobial formulations was typically established many years ago and studies comparing efficacy among various commercial DCT products are largely lacking. The objectives of this study were to evaluate and compare the 1) ability to cure existing intramammary infections (IMI) present at dry-off, 2) ability to prevent new IMI during the dry period, and 3) overall risk for presence of IMI after calving among three DCT products.

Insights into udder health and intramammary antibiotic usage on Irish dairy farms during 2003-2010.

By international standards, Ireland is a relatively small dairy producer. However, the industry plays a critical role to the national economy, accounting for approximately 3% of national gross domestic product. This paper presents insights into udder health and intramammary antibiotic usage on Irish dairy farms during 2003-2010, based on data from several sources. Three data sources were used, including data on milk recording data, intramammary antibiotic sales and animal health assessment. The milk recording data included a single unadjusted herd-level somatic cell count (SCC) value for each herd at each milk recording, being the arithmetic mean of cow-level SCC of each cow at that recording, weighted by cow-level yield. These data were used to calculate the percentage of herds each month where the unadjusted herd SCC exceeded 200,000 and 400,000 cells/mL. Two logistic generalised estimating-equations (GEE) models were developed, the outcome variable being either the probability that the monthly SCC of a herd was greater than 400,000 cells/mL or less than or equal to 200,000 cells/mL. Spring herds had a lower probability of a high SCC (> 400,000 cells/mL) during February to October compared to non-Spring herds but a higher probability between November to January. The odds of a high SCC were greater in 2005, 2006, 2009 and 2010 but less in 2007 and 2008 compared to 2004. Smaller herds had higher odds of having a high SCC compared to larger herds. We present the number of intramammary tubes and the quantity of active substance (kg) sold annually in Ireland during 2003-2010. We infer an incidence of clinical mastitis of 54.0 cases per 100 cow-years at risk, assuming 4 tubes per treatment regime, one affected quarter per cow, tubes restricted to clinical cases only and 100% of treated cases considered new cases, based on data collected on sales of in-lactation intra-mammary antibiotics. With differing assumptions, this estimate varied between 25.8 and 77.0 cases per 100 cow-years at risk. Using data on sales of dry cow therapy intra-mammary antibiotics, we also infer that most Irish dairy farmers use blanket dry cow therapy. It is important that Ireland has an objective understanding of current levels of udder health, to facilitate benchmarking and improvement into the future. Udder health is a concern on a number of Irish dairy farms. High SCC results were present throughout the year, but more marked towards the start and end of each milking season. Animal Health Ireland recently commenced a major national programme, CellCheck, in collaboration with a broad range of stakeholders, to support national SCC improvement. In this paper, relevant European and national legislation is also reviewed.

Manageable risk factors associated with the lactational incidence, elimination, and prevalence of Staphylococcus aureus intramammary infections in dairy cows

Staphylococcus aureus intramammary infections (IMI) are a major cause of mastitis on farms worldwide. Incidence and elimination rates are the key determinants of prevalence of Staph. aureus, and risk factors associated with these rates must be identified, prioritized, and controlled to obtain long-term reduction in prevalence. The objectives of this study were to identify manageable risk factors associated with the lactational incidence, elimination, and prevalence of Staph. aureus IMI. A cohort of 90 Canadian dairy farms was recruited and followed in 2007 and 2008. Quarter milk samples were collected repeatedly from a selection of cows, and bacteriological culture was realized to assess incidence, elimination, and prevalence of Staph. aureus IMI. Practices used on farms were measured using direct observations and a validated questionnaire. A linear regression model was used to explore the relationship between herd IMI prevalence and incidence and elimination rates. Multilevel logistic regression models were used to compute measures of associations between practices used on farms and IMI incidence, elimination, and prevalence. The herd incidence rate was the most important predictor of herd IMI prevalence: a reduction of the incidence rate equivalent to its interquartile range (0.011 new IMI/quarter-month) was associated with a prevalence reduction of 2.2 percentage points; in comparison, an equivalent increase of the elimination rate by its interquartile range (0.36 eliminated IMI/quarter-month) resulted in a prevalence reduction of 0.4 percentage points. Postmilking teat disinfection and blanket dry-cow therapy were already implemented by most herds. Most of the practices associated with Staph. aureus IMI incidence were related to milking procedures. Among these, wearing gloves during milking showed desirable associations with IMI incidence, elimination, and prevalence. Similarly, adequate teat-end condition and use of premilking teat disinfection were associated with lower IMI incidence and prevalence. The initial herd prevalence of Staph. aureus IMI was positively associated with subsequent IMI incidence. This indicates that, in some situations, an initial reduction of the pool of infected quarters could be justified. Some housing practices were associated with IMI incidence, elimination, or prevalence. The effects of these latter practices, however, were often influenced by specific cow characteristics such as parity or days in milk. These results highlight the importance of good milking practices to prevent Staph. aureus IMI acquisition and, therefore, reduce their prevalence.

A simulation model to calculate costs and benefits of dry period interventions in dairy cattle

An existing dynamic and stochastic bio-economic model of intramammary infection (IMI) caused by Staphylococcus aureus, Streptococcus uberis, Streptococcus dysgalactiae, and Escherichia coli was extended to model the dynamics of IMI during the dry period. These dynamics were modeled on the basis of a Greenwood model. The extended model was used to calculate the cost-effectiveness of different dry period interventions in relation to the annual net costs of IMI in a herd of 100 dairy cows at the start. The interventions were blanket dry cow therapy (BDCT) as the default scenario, BDCT combined with teat sealant (TS), selective dry cow therapy (SDCT) or TS, and SDCT combined with TS. Input parameters of the dynamics of IMI during the dry period and the economic parameters were based on literature. The costs of clinical and subclinical IMI during lactation, clinical IMI during the dry period, and the cost of intervention were used to calculate the combined total annual net cost of IMI per herd. The combined total annual net cost of IMI using the other intervention scenarios was compared to the default scenario (BDCT) to estimate the cost-effectiveness of the other intervention scenarios. Sensitivity analysis was conducted on the parameters involved. The results showed that a considerable number of cows acquire new IMI during the dry period and start the new lactation with IMI. Furthermore, the average combined total annual net cost of IMI per herd using BDCT was € 8800, distributed as € 4561 due to clinical IMI, and € 3063 due to subclinical IMI during lactation, € 88 due to clinical IMI during the dry period, and € 1088 due to antibiotic therapy and labor costs at dry off. On average, application of BDCT combined with TS resulted in € 378 higher combined total annual net cost of IMI compared to the BDCT scenario. Similarly, the SDCT scenarios resulted in higher average combined total annual net costs of IMI compared to the BDCT scenario. The SDCT or TS was on average € 443 higher and the SDCT combined with TS was on average € 635 higher. Sensitivity analysis results showed that the rate of new IMI during the dry period was the most influential parameter on the average combined total annual net cost of IMI. Although the difference between the 4 simulated scenarios was minor, on average BDCT had the lowest combined total annual net cost of IMI.

Meta-analysis of dry cow management for dairy cattle. Part 1. Protection against new intramammary infections

The objective of this study was to estimate the preventive effect of various dry cow management measures against quarter new intramammary infections (IMI) during the dry period up to 21 d postcalving. Moreover, the potential publication bias was assessed in the studies selected for this analysis. The intervention measures were blanket dry cow therapy (BDCT), selective dry cow therapy (SDCT), cloxacillin compared with other dry cow therapy products, and teat sealant. A meta-analysis relative risk (RR) was calculated per intervention and pathogen group when enough studies were available from the 33 selected studies. Results of the meta-analyses were examined using publication bias tests. Blanket dry cow therapy showed significant protection against new IMI caused by Streptococcus spp. [the pooled RR was 0.39 (0.30 to 0.51)] but no protection was observed against coliform new IMI [the pooled RR was 0.95 (0.81 to 1.10)]. After correction for publication bias, it became doubtful whether DCT is protective against new Staphylococcus spp. IMI. Cloxacillin showed similar protection against new quarter IMI compared with other DCT products [the pooled RR was 1.09 (0.94 to 1.25)]. Selective dry cow therapy showed higher protection against new IMI compared with no DCT [the pooled RR was 0.51 (0.30 to 0.86)]. However, BDCT showed more protection when compared with SDCT [the pooled RR was 0.55 (0.37 to 0.80)], but the inference about whether BDCT is superior to SDCT was dependent on whether the selection criteria for SDCT was at the cow or quarter level. Internal teat sealants showed significant protection against new IMI during the dry period [the pooled RR was 0.39 (0.18 to 0.82)]. Publication bias should be taken into account when attempts are made to review literature in a meta-analysis.

Meta-analysis of dry cow management for dairy cattle. Part 2. Cure of existing intramammary infections

The main goal of dry cow therapy (DCT) is to cure existing intramammary infections (IMI) at dry off. Although several published studies have estimated the cure rate of IMI after DCT, variation among studies is great, which makes it difficult to conduct a proper economic evaluation of DCT. The objective of the present meta-analysis of existing peer-reviewed literature was to provide a summary quantification of quarter IMI cure based on DCT. A meta-analysis relative risk (RR) was calculated per intervention and pathogen group when at least 4 studies were available for analysis per comparison from the 22 selected studies, according to the selection criteria. Results of the meta-analysis were examined using publication bias tests. Blanket DCT with a 95% confidence interval (CI) provided a 1.78 (1.51 to 2.10) times higher calculated cure rate from quarter IMI during the dry period up to 21 d postcalving, compared with no DCT. The RR of cure was similar when treatment was conducted for Streptococcus spp. IMI quarters compared with Staphylococcus spp. IMI quarters. The pooled RR with the 95% CI were 1.83 (1.48 to 2.35) and 1.65 (1.38 to 1.96), respectively. There was no significant difference between cloxacillin and other DCT products in the cure of quarter IMI during the dry period up to 21 d postcalving. The pooled RR with the 95% CI was 1.00 (0.92 to 1.09). Similarly, there was no significant difference between cloxacillin and other DCT products in the cure of quarter Staphylococcus spp. IMI. The pooled RR with the 95% CI was 1.00 (0.96 to 1.06). The pooled RR with the 95% CI of quarter IMI cure using selective DCT, compared with no DCT, was 1.76 (1.23 to 2.54).

Intramammary infection rate during the dry period in cows that received blanket dry cow therapy : efficacy of 6 different dry-cow intra-mammary antimicrobial products

The objectives of this study were to compare the efficacy of 6 different dry-cow intramammary antimicrobial products for the treatment and prevention of mastitis during the dry period in a well-managed high producing Friesland dairy herd, and the influence of treatment on the somatic cell count (SCC) of cows during early lactation. One of 6 dry-cow intramammary antimicrobial products was randomly allocated to 162 cows due for drying off over a period of 14 months. All cows were sampled twice prior to drying off, and twice after calving for the determination of SCC and presence of microorganisms. The quarter prevalence of pathogens at drying off and post-calving, the overall quarter cure rate and the rate of new intramammary infections occurring during the dry period were determined. The overall quarter prevalence of intramammary infections (IMIs) at drying off was 29.78% and after calving 22.22%. There was a statistically significant difference (P < 0.05) between the prevalence of major and minor pathogens at drying off (7.87% and 21.91%) and at calving (4.47% and 17.75%). The most prevalent pathogens isolated at drying off (21.14%) and at calving (16.98%) were coagulase-negative staphylococci (CNS). The quarter cure rate during the dry period was 83.94%. The cure rate for the major pathogens (98%) was significantly better (P < 0.05) than that for minor pathogens (78.9%). The overall quarter cure rate varied from 72.3% to 93.9% for the various products. The rate of new quarter infections during the dry period was 17.44% with a significant difference (P < 0.05), between the prevalence of new quarter infections with major (4.32%) and minor pathogens (13.12%). CNS was the most prevalent pathogen causing new quarter infections (12.34%) and the rate of new quarter infections varied from 13.4% to 24.1% for the various products. It is concluded that there is a difference in efficacy between antimicrobial intramammary dry-cow products in their ability to cure and prevent new IMIs during the dry period. Dry-cow products are mainly formulated for efficacy against Gram-positive cocci, while providing no or little protection against Gram-negative bacteria. Therapeutic levels may persist for only 14 to 28 days into the dry period and fail to protect the udder during the last trimester. Dry-cow therapy should, however, always form part of a holistic approach to the dry period which also considers cow factors, dry-cow management, microorganisms and the environment of the dry cow.

Stochastic Modeling to Determine the Economic Effects of Blanket, Selective, and No Dry Cow Therapy

In many countries, blanket dry cow therapy (DCT) is the standard way to dry off cows. Because of concerns about antibiotic resistance, selective DCT is proposed as an alternative. The economic consequences of different types of DCT were studied previously, but variation between input traits and different types of pathogens were not taken into account. The goal of this study was to create a stochastic Monte Carlo model to simulate the dynamics of intramammary infections (IMI) around the dry period to predict the economic consequences of DCT for different types of pathogens (Streptococcus agalactiae, Streptococcus dysgalactiae, Streptococcus uberis, Staphylococcus aureus, and Escherichia coli). The traits used in the model can be varied. The probabilities within the basic situation were collected from the literature and, because not all information needed was available in the literature, by interviewing experts (n = 10). The expert opinions were translated into minimum, most expected, and maximum values for each of the different probabilities. For Dutch farmers, the costs associated with mastitis and mastitis control around the dry period varied between ∉10.61 and ∉26.61 (average ∉15.60) for blanket DCT, between ∉4.86 and ∉29.41 (average ∉13.72) for selective DCT, and between ∉4.08 and ∉42.60 (average ∉18.02) for no DCT. Although there were small differences between the treatment groups, the variation within the treatment groups was much larger. The major portion of the costs for selective treatment (59% of the total costs) and no DCT (82%) was derived from the costs of clinical mastitis after calving, and for blanket DCT, the costs of treatment (65%) exceeded the costs of clinical mastitis (27%). The cost of mastitis around the dry period was most sensitive to a change in the risk of new IMI during the dry period, spontaneous cure, and costs associated with the antibiotic treatment. The optimal decision to dry off cows depends on the attitude of the farmer toward risk and other farm-specific traits and probabilities such as the new IMI rate during the dry period. Therefore, it is necessary to make farm-specific calculations so that farmers are able to factor this information into their decisions when choosing the best DCT for their situations.

Étude Sur La Prevalence De Streptococcus Agalactiae et Staphylococcus Aureus Dans Les Troupeaux Du Quebec Par La Culture Séquentille Du Reservoir

This study was done on 325 dairy farms in Quebec, Canada to estimate S. agalactiae and S. aureus herd infection prevalence and their impact on milk production and quality. A maximum of 3 bulk tank milk sample were collected in each selected farm for bacteriology and somatic cell counting. A questionnaire for evaluation of farm management and mastitis control practices was administered during the first visit. The study reveals a herd infection prevalence for S. agalactiae and S. aureus of 43% and 93.4% respectively; 4.7% are negative to both bacteria. Adoption on a regular basis of teat dipping of all cows and blanket dry cow therapy is 60.8% and 34% respectively. The high prevalence results for S. agalactiae and S. aureus and the poor adoption of basic mastitis control practices give us a basis to improve upon with a mastitis control program.&#x0D; Article in French, English and Spanish summaries on PDF