Economic effects of garlic bolus supplementation to dairy cows in the dry period.

Abstract

Due to global concerns about antimicrobial resistance and since preventive use of antimicrobials in the Netherlands is no longer allowed, Dutch dairy farmers are looking for alternatives for dry cow therapy. Recently, supplementing dry cows with garlic boluses, as an alternative for preventive antimicrobial therapy, has become more popular in the Netherlands. Because economic losses are one of the main factors for a farmer to improve mastitis management, it is important to know whether supplementing dry cows with garlic boluses is economically beneficial. The aim of this study was to calculate whether the supplementation of oral garlic boluses used as a preventive measure against mastitis in the dry period and the first 14 days of lactation could be economically profitable under Dutch circumstances, considering variation in parameters and probabilities. A stochastic Monte Carlo simulation model was developed simulating 10,000 multiparous cows in the dry period and the first 14 days of the successive lactation. Factors in the model included the probability of the cow developing mastitis in the dry period, at calving and or the first 14 days of lactation, the probability of bacteriological and or clinical cure after treatment, the probability of spontaneous cure and the physiological effects of the infection. Two scenarios were simulated, where in the first scenario the cow was supplemented with garlic boluses in the dry period and the second scenario where the cow was not supplemented. The consequences of supplementing or not supplementing garlic boluses were simulated and total average costs per scenario were calculated. Finally, total average costs were compared for the two scenarios. Some inputs for the model were based on literature and assumptions made by the author were used if no information from literature was available. The average costs of a non-supplemented cow were estimated to be €103 per cow, under default circumstances. On average, the total costs decreased with €5 when a cow was supplemented with garlic boluses in the dry period. The decrease in costs for factors such as milk production losses, discarded milk and culling did outweigh the additional costs of supplementing a cow with garlic boluses of €47 (bolus and labour costs). A sensitivity analyses showed that the profitability of supplementing a cow with garlic boluses depend on farm-specific factors (such as culling costs and milk price) and cow-specific factors (such as the probability of occurrence of mastitis during lactation). It also showed that costs made during lactation had the greatest influence on the total costs, so for supplementing the garlic boluses to become economically profitable, they should have a significant positive effect on the occurrence of mastitis during lactation.