Economic optimization of selective dry cow treatment

Abstract

The objective of this study was to develop a mathematical model to identify a scenario with the lowest costs for mastitis associated with the dry period while restricting the percentage of cows to be dried off with dry cow antimicrobials. Costs of clinical and subclinical mastitis as well as antimicrobial use were quantified. Based on data from a large field trial, a linear programming model was built with the goal to minimize the costs associated with antimicrobial use at drying off. To enable calculations on minimizing costs of dry cow treatment on herd-level by drying-off decisions in an "average" herd, we created an example herd. Cows were projected on 3 different types of herds, based on bulk tank somatic cell count, and were categorized in groups based on parity and somatic cell count from the last test recording before drying-off. Economically optimal use of antimicrobials was determined while restricting the maximum percentage of cows dried off with antimicrobials from 100 to 0%. This restriction reveals the relationship between the maximum percentage of cows dried off with antibiotics and the economic consequences. A sensitivity analysis was performed to evaluate the effect of variation in the most important input variables, with the effect of dry cow antimicrobials resulting in a lower or higher percentage of clinical and subclinical mastitis depending on being dried off with or without dry cow antimicrobials, respectively, and the milk price. From an economic perspective, blanket dry cow treatment seems not to be the optimal approach of dry cow therapy, although differences between approaches were small. With lower bulk tank somatic cell counts, more dry cow antimicrobials can be omitted without economic consequences. The economic impact of reducing the percentage of clinical mastitis was found to be much larger than reducing the bulk tank somatic cell count. The optimal percentage of cows to be dried off with antimicrobials depends on the udder health situation, expressed as the bulk tank somatic cell count and the incidence of clinical mastitis. For all evaluated types of herds, selective dry cow treatment was economically more beneficial than blanket dry cow treatment. Economic profits of selective dry cow treatment are greater if bulk tank somatic cell count and clinical mastitis incidence are lower. Economics is not an argument against reduction of dry cow antimicrobials by applying selective dry cow treatment.

Rational Decision On the Use of Antibiotics During the Dry Period in Dairy Cows

“…The economic viability of STDC is related to the incidence of mastitis in each herd, that is, the decrease in the use of antibiotics is directly related to the incidence of subclinical mastitis at the end of lactation within each herd (9) .…”

“…Using the culture test at the end of the D-70 lactation, it has a greater number of negative teats diagnosed, using fewer antibiotics and reducing the cost of treatment in the dry period. Selective treatment at the time of drying using the culture method may be economically more viable than BDCT if the number of intramammary infections is low with lower intramammary antibiotic expense (9, 42) .…”

“…In dairy cows, besides the use of antibiotics in the treatment of clinical and subclinical mastitis during lactation, the use of antibiotics for intramammary use at the time of drying among lactations is also used, but without the proper diagnosis of mastitis, with application of antibiotics in all teats and generally with association with internal sealant, acting as mechanical barrier against environmental agents in the pre-labour (8,9) .…”

“…Many studies on the selective treatment in the drying period consider the cow with a history of SCC during lactation (8,9,14) . It can be noticed that there is a need for further studies with individual evaluation of mammary quarters for an even greater reduction in the use of antibiotics (15) .…”

The Effect of Selective Dry Cow Treatment on the Udder Health in Swiss Dairy Farms

“…Veröffentlichungen aus den Niederlanden wiesen jedoch auf die Besorgnis von Seiten der Landwirte und Tierärzte über die mögliche Zunahme von klinischen und subklinischen Mastitiden und deren Konsequenzen auf das Wohlergehen und die Leistung der Tiere hin. 28,30 In einer Studie aus der Schweiz wurde das Eutergesundheitsmanagement in 100 Milchviehbetrieben mit Tankzellzahlen von 200'000 bis 300'000 Zellen/ml untersucht. In 69% der Betriebe wurden alle Kühe antibiotisch trockengestellt und lediglich in 2% der Betriebe wurden regelmässig interne Zitzenversiegler benutzt.…”