Factors affecting the cost-effectiveness of on-farm culture prior to the treatment of clinical mastitis in dairy cows

The objective of this study was to use probabilistic sensitivity analysis to evaluate the cost-effectiveness of using an on-farm culture (OFC) approach to the treatment of clinical mastitis in dairy cows and compare this to a ‘standard’ treatment approach. A specific aim was to identify the herd circumstances under which an OFC approach would be most likely to be cost-effective. A stochastic Monte Carlo model was developed to simulate 5000 cases of clinical mastitis at the cow level and to calculate the associated costs simultaneously when treated according to 2 different treatment protocols; i) a 'conventional' approach (3 tubes of intramammary antibiotic) and ii) an OFC programme, whereby cows are treated according to the results of OFC. Model parameters were taken from recent peer reviewed literature on the use of OFC prior to treatment of clinical mastitis. Spearman rank correlation coefficients were used to evaluate the relationships between model input values and the estimated difference in cost between the standard and OFC treatment protocols. The simulation analyses revealed that both the difference in the bacteriological cure rate due to a delay in treatment when using OFC and the proportion of Gram-positive cases that occur on a dairy unit would have a fundamental impact on whether OFC would be cost-effective. The results of this study illustrated that an OFC approach for the treatment of clinical mastitis would probably not be cost-effective in many circumstances, in particular, not those in which Gram-positive pathogens were responsible for more than 20% of all clinical cases. The results highlight an ethical dilemma surrounding reduced use of antimicrobials for clinical mastitis since it may be associated with financial losses and poorer cow welfare in many instances

Decision tree analysis to evaluate dry cow strategies under UK conditions

Economic decisions on animal health strategies address the cost-benefit aspect along with animal welfare and public health concerns. Decision tree analysis at an individual cow level highlighted that there is little economic difference between the use of either dry cow antibiotic or an internal teat sealant in preventing a new intramammary infection in a cow free of infection in all quarters of the mammary gland at drying off. However, a potential net loss of over pound20 per cow might occur if the uninfected cow was left untreated. The only economically viable option, for a cow with one or more quarters infected at drying off, is antibiotic treatment, although a loss might still be incurred depending on the pathogen concerned and the cure rates achievable. There was a net loss for cows with quarters infected with Corynebacterium spp. at drying off, for both the teat sealant and untreated groups (pound22 and pound48, respectively) with only antibiotic-treated cows showing a gain

Lipid consumption in ixodes ricinus (acari : ixodidae): temperature and potential longevity

The effect of temperature on the rate of consumption of the lipid reserves in Ixodes ricinus Linnaeus was characterized in constant temperature experiments. There was a consistent linear relationship between temperature and lipid consumption in nymphs and adult females and males between 5 and 37°C. Nymphs and adults were able to withstand extended periods of exposure to temperatures within the range of 2-37°C, although at 2°C there was evidence of thermal stress. The variance about the median rate of lipid consumption was found to increase with increasing rate of lipid consumption. Predictions of longevity were made using the rates of lipid consumption for the three stages studied, which ranged from 16 weeks to more than two years depending on temperature and stage. The predictions were consistent with reported survival times for I. ricinus and followed patterns reported for other ixodid ticks